$CBSH
COMMERCE BANCSHARES INC /MO/ Stock $cbsh

$cbsh Overview Financials Valuation SEC Filings Company Website

2020 Q1 Form 10-K Financial Statement

#000002235620000009 Filed on February 25, 2020

Income Statement

Concept	2020 Q1	2018 Q4	2017 Q4
Revenue	$0.00
YoY Change
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$10.60M	$9.900M	$10.20M
YoY Change	6.0%	-2.94%	3.03%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$20.42M
YoY Change	-16.23%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$59.78M	$137.3M	$115.1M
YoY Change	-50.15%	19.29%	9.93%
Income Tax	$10.17M	$26.50M	$26.90M
% Of Pretax Income	17.02%	19.3%	23.37%
Net Earnings	$51.86M	$109.7M	$94.40M
YoY Change	-46.62%	16.21%	31.84%
Net Earnings / Revenue
Basic Earnings Per Share	$0.42
Diluted Earnings Per Share	$0.42	$855.7K	$732.9K
COMMON SHARES
Basic Shares Outstanding	112.1M shares	106.2M shares	101.6M shares
Diluted Shares Outstanding

Balance Sheet

Concept	2020 Q1	2018 Q4	2017 Q4
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$899.5M	$1.209B	$511.8M
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment	$369.7M	$333.1M	$335.1M
YoY Change	1.95%	-0.59%	-0.77%
Goodwill	$138.9M	$138.9M	$138.9M
YoY Change	0.0%	0.0%	0.0%
Intangibles	$8.433M	$8.794M	$7.618M
YoY Change	-0.92%	15.44%	13.55%
Long-Term Investments
YoY Change
Other Assets
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$26.79B	$25.46B	$24.83B
YoY Change	7.03%	2.54%	-3.15%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses
YoY Change
Deferred Revenue
YoY Change
Short-Term Debt	$1.428B	$1.956B	$1.507B
YoY Change	-17.12%	29.79%	-12.59%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$1.428B	$1.956B	$1.507B
YoY Change	5000.0%	29.79%	-12.59%
LONG-TERM LIABILITIES
Long-Term Debt	$756.0M	$9.000M	$2.000M
YoY Change	37700.0%	350.0%	-98.04%
Other Long-Term Liabilities	$580.0M	$238.0M	$181.0M
YoY Change	120.53%	31.49%	-15.02%
Total Long-Term Liabilities	$1.336B	$247.0M	$183.0M
YoY Change	404.15%	34.97%	-41.9%
TOTAL LIABILITIES
Total Short-Term Liabilities	$1.428B	$1.956B	$1.507B
Total Long-Term Liabilities	$1.336B	$247.0M	$183.0M
Total Liabilities	$23.54B	$22.53B	$22.12B
YoY Change	7.05%	1.86%	-4.43%
SHAREHOLDERS EQUITY
Retained Earnings	$224.6M	$241.2M	$221.4M
YoY Change	-26.87%	8.94%	-24.41%
Common Stock	$564.0M	$559.4M	$535.4M
YoY Change	0.81%	4.49%	4.98%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$69.15M	$34.24M	$14.47M
YoY Change	14.21%	136.55%	-5.37%
Treasury Stock Shares	1.040M shares	555.1K shares	277.0K shares
Shareholders Equity	$3.251B	$2.931B	$2.717B
YoY Change
Total Liabilities & Shareholders Equity	$26.79B	$25.46B	$24.83B
YoY Change	7.03%	2.54%	-3.15%

Cashflow Statement

Concept	2020 Q1	2018 Q4	2017 Q4
OPERATING ACTIVITIES
Net Income	$51.86M	$109.7M	$94.40M
YoY Change	-46.62%	16.21%	31.84%
Depreciation, Depletion And Amortization	$10.60M	$9.900M	$10.20M
YoY Change	6.0%	-2.94%	3.03%
Cash From Operating Activities	$79.77M	$106.0M	$92.20M
YoY Change	-43.9%	14.97%	5.98%
INVESTING ACTIVITIES
Capital Expenditures	$7.574M	-$11.90M	-$7.900M
YoY Change	-32.87%	50.63%	31.67%
Acquisitions
YoY Change
Other Investing Activities	-$274.0M	$47.70M	-$92.60M
YoY Change	1270.0%	-151.51%	-86.89%
Cash From Investing Activities	-$281.6M	$35.80M	-$100.5M
YoY Change	799.03%	-135.62%	-85.89%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net	$53.15M
YoY Change	33.87%
Debt Paid & Issued, Net	$0.00
YoY Change	-100.0%
Cash From Financing Activities	$193.5M	262.4M	-86.30M
YoY Change	-127.12%	-404.06%	-109.17%
NET CHANGE
Cash From Operating Activities	$79.77M	106.0M	92.20M
Cash From Investing Activities	-$281.6M	35.80M	-100.5M
Cash From Financing Activities	$193.5M	262.4M	-86.30M
Net Change In Cash	-$8.294M	404.2M	-94.60M
YoY Change	-98.62%	-527.27%	-129.99%
FREE CASH FLOW
Cash From Operating Activities	$79.77M	$106.0M	$92.20M
Capital Expenditures	$7.574M	-$11.90M	-$7.900M
Free Cash Flow	$72.19M	$117.9M	$100.1M
YoY Change	-44.85%	17.78%	7.63%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2019	dei	Amendment Flag AmendmentFlag	false
CY2019	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2019	dei	Entity Central Index Key EntityCentralIndexKey	0000022356
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CY2019	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	43-0889454
CY2019	dei	Entity Address Address Line1 EntityAddressAddressLine1	1000 Walnut,
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CY2019	dei	Document Period End Date DocumentPeriodEndDate	2019-12-31
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CY2019	cbsh	Definedbenefitplandiscretionarycontributionbyemployer Definedbenefitplandiscretionarycontributionbyemployer	0	USD
CY2019Q4	cbsh	Hfs Student Loans Past Due HFSStudentLoansPastDue	0	USD
CY2019Q4	cbsh	Hfs Student Loanson Non Accrual Status HFSStudentLoansonNonAccrualStatus	0	USD
CY2017	cbsh	Interest Expense Capitalizedon Construction Projects InterestExpenseCapitalizedonConstructionProjects	0	USD
CY2019	dei	Document Transition Report DocumentTransitionReport	false
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CY2019	cbsh	Interest Expense Capitalizedon Construction Projects InterestExpenseCapitalizedonConstructionProjects	0	USD
CY2019	dei	Entity File Number EntityFileNumber	0-2989
CY2017Q4	cbsh	Investment Securities Pledged At Fair Value InvestmentSecuritiesPledgedAtFairValue	4300000000	USD
CY2019Q4	cbsh	Personal Real Estate Loans Hfs Past Due PersonalRealEstateLoansHFSPastDue	0	USD
CY2019Q4	cbsh	Personal Real Estate Loans Hf Son Non Accrual Status PersonalRealEstateLoansHFSonNonAccrualStatus	0	USD
CY2017	cbsh	Stock Dividend Rate StockDividendRate	0.05
CY2019	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
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CY2018Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	120000000	shares
CY2019Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	140000000	shares
CY2018Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	11886450	shares
CY2019Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	112795605	shares
CY2018	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21	Rate
CY2019	dei	City Area Code CityAreaCode	816
CY2019	dei	Local Phone Number LocalPhoneNumber	234-2000
CY2018	cbsh	Stock Dividend Rate StockDividendRate	0.05
CY2017	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
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CY2019	dei	Entity Address City Or Town EntityAddressCityOrTown	Kansas City,
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CY2019	dei	Entity Registrant Name EntityRegistrantName	COMMERCE BANCSHARES, INC.
CY2019	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	MO
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CY2018	cbsh	Interest On Other Borrowings InterestOnOtherBorrowings	45000	USD
CY2017	cbsh	Interest On Other Borrowings InterestOnOtherBorrowings	3086000	USD
CY2019	us-gaap	Interest Expense InterestExpense	103392000	USD
CY2018	us-gaap	Interest Expense InterestExpense	65376000	USD
CY2017	us-gaap	Interest Expense InterestExpense	43728000	USD
CY2019	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	821293000	USD
CY2018	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	823825000	USD
CY2017	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	733679000	USD
CY2019	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	50438000	USD
CY2018	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	42694000	USD
CY2017	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	45244000	USD
CY2019	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	770855000	USD
CY2018	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	781131000	USD
CY2017	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	688435000	USD
CY2019	cbsh	Bank Card Transaction Fees BankCardTransactionFees	167879000	USD
CY2018	cbsh	Bank Card Transaction Fees BankCardTransactionFees	171576000	USD
CY2017	cbsh	Bank Card Transaction Fees BankCardTransactionFees	155100000	USD
CY2019	cbsh	Trustfeerevenue Trustfeerevenue	155628000	USD
CY2018	cbsh	Trustfeerevenue Trustfeerevenue	147964000	USD
CY2017	cbsh	Trustfeerevenue Trustfeerevenue	135159000	USD
CY2019	cbsh	Depositfeerevenue Depositfeerevenue	95983000	USD
CY2018	cbsh	Depositfeerevenue Depositfeerevenue	94517000	USD
CY2017	cbsh	Depositfeerevenue Depositfeerevenue	90060000	USD
CY2019	us-gaap	Noninterest Income Other NoninterestIncomeOther	8146000	USD
CY2018	us-gaap	Noninterest Income Other NoninterestIncomeOther	7721000	USD
CY2017	us-gaap	Noninterest Income Other NoninterestIncomeOther	7996000	USD
CY2019	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	15804000	USD
CY2018	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	15807000	USD
CY2017	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	14630000	USD
CY2019	cbsh	Loan Fees And Sales LoanFeesAndSales	15767000	USD
CY2018	cbsh	Loan Fees And Sales LoanFeesAndSales	12723000	USD
CY2017	cbsh	Loan Fees And Sales LoanFeesAndSales	13948000	USD
CY2019	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	65496000	USD
CY2018	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	51033000	USD
CY2017	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	44370000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	524703000	USD
CY2018	us-gaap	Noninterest Income NoninterestIncome	501341000	USD
CY2017	us-gaap	Noninterest Income NoninterestIncome	461263000	USD
CY2017	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	80998000	USD
CY2019	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	6676000	USD
CY2019	us-gaap	Labor And Related Expense LaborAndRelatedExpense	492927000	USD
CY2019	us-gaap	Marketing Expense MarketingExpense	21914000	USD
CY2018	us-gaap	Marketing Expense MarketingExpense	20548000	USD
CY2017	us-gaap	Marketing Expense MarketingExpense	16325000	USD
CY2018	us-gaap	Labor And Related Expense LaborAndRelatedExpense	468194000	USD
CY2017	us-gaap	Labor And Related Expense LaborAndRelatedExpense	448321000	USD
CY2019	us-gaap	Occupancy Net OccupancyNet	47157000	USD
CY2018	us-gaap	Occupancy Net OccupancyNet	46044000	USD
CY2017	us-gaap	Occupancy Net OccupancyNet	45612000	USD
CY2019	us-gaap	Equipment Expense EquipmentExpense	19061000	USD
CY2019	cbsh	Supplies Postage And Communication SuppliesPostageAndCommunication	20394000	USD
CY2018	cbsh	Supplies Postage And Communication SuppliesPostageAndCommunication	20637000	USD
CY2017	cbsh	Supplies Postage And Communication SuppliesPostageAndCommunication	22790000	USD
CY2019	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	92899000	USD
CY2018	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	85978000	USD
CY2018	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	11546000	USD
CY2017	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	13986000	USD
CY2019	cbsh	Community Service CommunityService	2446000	USD
CY2018	cbsh	Community Service CommunityService	2445000	USD
CY2017	cbsh	Community Service CommunityService	34377000	USD
CY2019	us-gaap	Other Noninterest Expense OtherNoninterestExpense	63924000	USD
CY2018	us-gaap	Other Noninterest Expense OtherNoninterestExpense	64304000	USD
CY2017	us-gaap	Other Noninterest Expense OtherNoninterestExpense	63366000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	767398000	USD
CY2018	us-gaap	Noninterest Expense NoninterestExpense	737821000	USD
CY2017	us-gaap	Noninterest Expense NoninterestExpense	744343000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	531786000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	544163000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	430406000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	109074000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	105949000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	110506000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	422712000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	438214000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	319900000	USD
CY2019	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	1481000	USD
CY2018	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	4672000	USD
CY2017	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	517000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	421231000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	433542000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	319383000	USD
CY2019	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	9000000	USD
CY2018	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	9000000	USD
CY2017	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	9000000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	412231000	USD
CY2018	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	424542000	USD
CY2017	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	310383000	USD
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.59
CY2018	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	6370000	USD
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.61
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.63
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.58
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.60
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.62
CY2019	us-gaap	Profit Loss ProfitLoss	422712000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	438214000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	319900000	USD
CY2019	cbsh	Net Unrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings NetUnrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings	-632000	USD
CY2018	cbsh	Net Unrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings NetUnrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings	-277000	USD
CY2017	cbsh	Net Unrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings NetUnrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings	412000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	151122000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-55631000	USD
CY2017	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	3022000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1167000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-664000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	301000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	23456000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	6855000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	175113000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-48389000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	3133000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	597825000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	389825000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	323033000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	1481000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	4672000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	517000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	596344000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	385153000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	322516000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	422712000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	438214000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	319900000	USD
CY2019	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	50438000	USD
CY2018	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	42694000	USD
CY2017	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	45244000	USD
CY2019	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	41145000	USD
CY2018	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	38679000	USD
CY2017	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	39732000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	5336000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	13617000	USD
CY2019	us-gaap	Gain Loss On Investments GainLossOnInvestments	3626000	USD
CY2018	us-gaap	Gain Loss On Investments GainLossOnInvestments	-488000	USD
CY2017	us-gaap	Gain Loss On Investments GainLossOnInvestments	25051000	USD
CY2019	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-27631000	USD
CY2018	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-26224000	USD
CY2017	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-35423000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	14195000	USD
CY2017	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	8008000	USD
CY2019	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	10127000	USD
CY2018	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	208431000	USD
CY2019	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	259153000	USD
CY2017	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	215373000	USD
CY2019	cbsh	Origination Of Loans Held For Sale OriginationOfLoansHeldForSale	244976000	USD
CY2018	cbsh	Origination Of Loans Held For Sale OriginationOfLoansHeldForSale	203775000	USD
CY2017	cbsh	Origination Of Loans Held For Sale OriginationOfLoansHeldForSale	216064000	USD
CY2019	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	-3863000	USD
CY2018	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	14277000	USD
CY2017	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	-7585000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	13854000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	12841000	USD
CY2017	us-gaap	Share Based Compensation ShareBasedCompensation	12105000	USD
CY2019	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	-3316000	USD
CY2018	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	4258000	USD
CY2017	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	4459000	USD
CY2019	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	5586000	USD
CY2018	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	2137000	USD
CY2017	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	38000	USD
CY2019	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	14465000	USD
CY2018	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	12288000	USD
CY2017	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	-27685000	USD
CY2019	cbsh	Donationofsecurities Donationofsecurities	0	USD
CY2018	cbsh	Donationofsecurities Donationofsecurities	0	USD
CY2017	cbsh	Donationofsecurities Donationofsecurities	32036000	USD
CY2019	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	11472000	USD
CY2018	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	0	USD
CY2017	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	0	USD
CY2019	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	73363000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	5992000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	13259000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	512794000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	552660000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	426527000	USD
CY2019	cbsh	Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities	413203000	USD
CY2018	cbsh	Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities	708864000	USD
CY2017	cbsh	Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities	792380000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	1558244000	USD
CY2018	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	1510985000	USD
CY2017	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	1899640000	USD
CY2019	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	1863180000	USD
CY2018	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	2090333000	USD
CY2017	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	1853817000	USD
CY2019	us-gaap	Payments For Securities Purchased Under Agreements To Resell PaymentsForSecuritiesPurchasedUnderAgreementsToResell	150000000	USD
CY2018	us-gaap	Payments For Securities Purchased Under Agreements To Resell PaymentsForSecuritiesPurchasedUnderAgreementsToResell	100000000	USD
CY2018	us-gaap	Proceeds From Securities Purchased Under Agreements To Resell ProceedsFromSecuritiesPurchasedUnderAgreementsToResell	100000000	USD
CY2019	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	647890000	USD
CY2018	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	200673000	USD
CY2017	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	614849000	USD
CY2017	us-gaap	Payments For Securities Purchased Under Agreements To Resell PaymentsForSecuritiesPurchasedUnderAgreementsToResell	75000000	USD
CY2019	us-gaap	Proceeds From Securities Purchased Under Agreements To Resell ProceedsFromSecuritiesPurchasedUnderAgreementsToResell	0	USD
CY2017	us-gaap	Proceeds From Securities Purchased Under Agreements To Resell ProceedsFromSecuritiesPurchasedUnderAgreementsToResell	100000000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	42575000	USD
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	33294000	USD
CY2017	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	30824000	USD
CY2019	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	2033000	USD
CY2018	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	13427000	USD
CY2017	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	3190000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-730165000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-91024000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	220720000	USD
CY2019	cbsh	Net Increase Decrease Non Interest Bearing Savings Interest Checking And Money Market Deposits NetIncreaseDecreaseNonInterestBearingSavingsInterestCheckingAndMoneyMarketDeposits	85438000	USD
CY2018	cbsh	Net Increase Decrease Non Interest Bearing Savings Interest Checking And Money Market Deposits NetIncreaseDecreaseNonInterestBearingSavingsInterestCheckingAndMoneyMarketDeposits	60278000	USD
CY2017	cbsh	Net Increase Decrease Non Interest Bearing Savings Interest Checking And Money Market Deposits NetIncreaseDecreaseNonInterestBearingSavingsInterestCheckingAndMoneyMarketDeposits	-15036000	USD
CY2019	us-gaap	Increase Decrease In Time Deposits IncreaseDecreaseInTimeDeposits	349890000	USD
CY2018	us-gaap	Increase Decrease In Time Deposits IncreaseDecreaseInTimeDeposits	-108742000	USD
CY2017	us-gaap	Increase Decrease In Time Deposits IncreaseDecreaseInTimeDeposits	-474044000	USD
CY2019	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	-105617000	USD
CY2018	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	449251000	USD
CY2017	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	-216767000	USD
CY2019	us-gaap	Repayments Of Debt And Capital Lease Obligations RepaymentsOfDebtAndCapitalLeaseObligations	6394000	USD
CY2018	us-gaap	Repayments Of Debt And Capital Lease Obligations RepaymentsOfDebtAndCapitalLeaseObligations	-6944000	USD
CY2017	us-gaap	Repayments Of Debt And Capital Lease Obligations RepaymentsOfDebtAndCapitalLeaseObligations	100291000	USD
CY2019	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	134904000	USD
CY2018	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	75231000	USD
CY2017	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	17771000	USD
CY2019	cbsh	Acceleratedstockrepurchaseagreement Acceleratedstockrepurchaseagreement	150000000	USD
CY2018	cbsh	Acceleratedstockrepurchaseagreement Acceleratedstockrepurchaseagreement	0	USD
CY2017	cbsh	Acceleratedstockrepurchaseagreement Acceleratedstockrepurchaseagreement	0	USD
CY2019	cbsh	Paymentsforstockvalueissuedundersharebasedcompensationplans Paymentsforstockvalueissuedundersharebasedcompensationplans	8000	USD
CY2018	cbsh	Paymentsforstockvalueissuedundersharebasedcompensationplans Paymentsforstockvalueissuedundersharebasedcompensationplans	10000	USD
CY2017	cbsh	Paymentsforstockvalueissuedundersharebasedcompensationplans Paymentsforstockvalueissuedundersharebasedcompensationplans	8000	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	113466000	USD
CY2018	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	100238000	USD
CY2017	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	91619000	USD
CY2019	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	9000000	USD
CY2018	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	9000000	USD
CY2017	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	9000000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-84061000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	223252000	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-924536000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	801641000	USD
CY2019	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-301432000	USD
CY2018	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	684888000	USD
CY2017	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-277289000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	1209240000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	524352000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	907808000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	1209240000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	524352000	USD
CY2019	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	76168000	USD
CY2018	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	84172000	USD
CY2017	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	120744000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	97806000	USD
CY2018	us-gaap	Interest Paid Net InterestPaidNet	63239000	USD
CY2017	us-gaap	Interest Paid Net InterestPaidNet	43690000	USD
CY2019	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	581000	USD
CY2018	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	1551000	USD
CY2017	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	2063000	USD
CY2016Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2501132000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	319900000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	3133000	USD
CY2017	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	1293000	USD
CY2017	us-gaap	Noncontrolling Interest Increase From Sale Of Parent Equity Interest NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest	1000	USD
CY2017	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	17771000	USD
CY2017	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	91619000	USD
CY2017	us-gaap	Dividends Preferred Stock Cash DividendsPreferredStockCash	9000000	USD
CY2017	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	12105000	USD
CY2017	cbsh	Stock Issued During Period Rs Asand Sa Rs StockIssuedDuringPeriodRSAsandSARs	858000	USD
CY2017	us-gaap	Stock Issued During Period Value Stock Dividend StockIssuedDuringPeriodValueStockDividend	-559000	USD
CY2017Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2718184000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	438214000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-48389000	USD
CY2018	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	445000	USD
CY2018	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	75231000	USD
CY2018	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	100238000	USD
CY2018	us-gaap	Dividends Preferred Stock Cash DividendsPreferredStockCash	9000000	USD
CY2018	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	12841000	USD
CY2018	cbsh	Stock Issued During Period Rs Asand Sa Rs StockIssuedDuringPeriodRSAsandSARs	1792000	USD
CY2018	us-gaap	Stock Issued During Period Value Stock Dividend StockIssuedDuringPeriodValueStockDividend	-579000	USD
CY2018Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2937149000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	422712000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	175113000	USD
CY2019	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	3544000	USD
CY2019	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	134904000	USD
CY2019	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	150000000	USD
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	113466000	USD
CY2019	us-gaap	Dividends Preferred Stock Cash DividendsPreferredStockCash	9000000	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	13854000	USD
CY2019	cbsh	Stock Issued During Period Rs Asand Sa Rs StockIssuedDuringPeriodRSAsandSARs	1351000	USD
CY2019	us-gaap	Stock Issued During Period Value Stock Dividend StockIssuedDuringPeriodValueStockDividend	-793000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3138472000	USD
CY2019	us-gaap	Nature Of Operations NatureOfOperations	<div style="line-height:120%;padding-bottom:8px;padding-top:8px;text-align:justify;padding-left:9px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-style:italic;">Nature of Operations</span></div><div style="line-height:120%;text-align:justify;text-indent:18px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Commerce Bancshares, Inc. and its subsidiaries (the Company) conducts its principal activities from approximately </span><span style="font-family:inherit;font-size:10pt;"><span>316</span></span><span style="font-family:inherit;font-size:10pt;"> branch and ATM locations throughout Missouri, Kansas, Illinois, Oklahoma and Colorado. Principal activities include retail and commercial banking, investment management, securities brokerage, mortgage banking, trust, and private banking services. The Company also maintains commercial banking offices in Dallas, Houston, Cincinnati, Nashville, Des Moines, Indianapolis, and Grand Rapids.</span></div>
CY2019Q4	cbsh	Number Of Locations NumberOfLocations	316	Locations
CY2019Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	20300000	USD
CY2018Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	8200000	USD
CY2019Q4	cbsh	Federal Reserve Bank Reserve Requirement FederalReserveBankReserveRequirement	160700000	USD
CY2019Q4	cbsh	Cash Heldat Federal Reserve Bank CashHeldatFederalReserveBank	395900000	USD
CY2019	cbsh	Amortization Period Of Credit Card Loan Annual Fees AmortizationPeriodOfCreditCardLoanAnnualFees	P12M
CY2019	cbsh	Period Past Due Loans Placed On Non Accrual PeriodPastDueLoansPlacedOnNonAccrual	P90D
CY2019	cbsh	Delinquency Period Consumer Loans Charged Down To Fair Value DelinquencyPeriodConsumerLoansChargedDownToFairValue	P120D
CY2019	cbsh	Delinquency Period Credit Card Loans Charged Off DelinquencyPeriodCreditCardLoansChargedOff	P180D
CY2019	cbsh	Common Stock Dividend Rate Percentage CommonStockDividendRatePercentage	0.05
CY2019Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	14737817000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	14140298000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	46728000	USD
CY2019	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	133607000	USD
CY2019	us-gaap	Loans And Leases Receivable Related Parties Proceeds LoansAndLeasesReceivableRelatedPartiesProceeds	123956000	USD
CY2019	cbsh	Loans And Lease Receivable Related Party Write Offs LoansAndLeaseReceivableRelatedPartyWriteOffs	0	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	56379000	USD
CY2019Q4	cbsh	Loans To Principal Holders LoansToPrincipalHolders	0	USD
CY2019Q4	cbsh	Unfunded Loan Commitments UnfundedLoanCommitments	11200000000	USD
CY2019Q4	cbsh	Unused Approved Credit Card Lines Of Credit UnusedApprovedCreditCardLinesOfCredit	5100000000	USD
CY2019Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Loans Receivable Pledged For Federal Home Loan Bank Debt PledgedFinancialInstrumentsNotSeparatelyReportedLoansReceivablePledgedForFederalHomeLoanBankDebt	4000000000.0	USD
CY2019Q4	cbsh	Pledged Financial Instruments Not Separately Reported Loans Pledged For Federal Reserve Bank Debt PledgedFinancialInstrumentsNotSeparatelyReportedLoansPledgedForFederalReserveBankDebt	1600000000	USD
CY2019Q4	us-gaap	Net Investment In Direct Financing And Sales Type Leases NetInvestmentInDirectFinancingAndSalesTypeLeases	795800000	USD
CY2018Q4	us-gaap	Net Investment In Direct Financing And Sales Type Leases NetInvestmentInDirectFinancingAndSalesTypeLeases	752200000	USD
CY2019Q4	us-gaap	Capital Leases Net Investment In Sales Type Leases Deferred Income CapitalLeasesNetInvestmentInSalesTypeLeasesDeferredIncome	71800000	USD
CY2018Q4	us-gaap	Capital Leases Net Investment In Sales Type Leases Deferred Income CapitalLeasesNetInvestmentInSalesTypeLeasesDeferredIncome	62600000	USD
CY2019Q4	us-gaap	Property Subject To Or Available For Operating Lease Net PropertySubjectToOrAvailableForOperatingLeaseNet	14700000	USD
CY2018Q4	us-gaap	Property Subject To Or Available For Operating Lease Net PropertySubjectToOrAvailableForOperatingLeaseNet	16100000	USD
CY2016Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	155932000	USD
CY2017	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	45244000	USD
CY2017	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	55179000	USD
CY2017	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	13535000	USD
CY2017	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	41644000	USD
CY2017Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	159532000	USD
CY2018	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	42694000	USD
CY2018	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	55821000	USD
CY2018	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	13527000	USD
CY2018	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	42294000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	159932000	USD
CY2019	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	50438000	USD
CY2019	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	61880000	USD
CY2019	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	12192000	USD
CY2019	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	49688000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	160682000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	2746000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	81732000	USD
CY2019Q4	cbsh	Loans And Leases Receivable Allowance Excluding Impaired Financing Receivable Related Allowance LoansAndLeasesReceivableAllowanceExcludingImpairedFinancingReceivableRelatedAllowance	157936000	USD
CY2019Q4	cbsh	Loans And Leases Receivable Excluding Impaired Financing Receivables Recorded Investment LoansAndLeasesReceivableExcludingImpairedFinancingReceivablesRecordedInvestment	14656085000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	2696000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	78616000	USD
CY2018Q4	cbsh	Loans And Leases Receivable Allowance Excluding Impaired Financing Receivable Related Allowance LoansAndLeasesReceivableAllowanceExcludingImpairedFinancingReceivableRelatedAllowance	157236000	USD
CY2018Q4	cbsh	Loans And Leases Receivable Excluding Impaired Financing Receivables Recorded Investment LoansAndLeasesReceivableExcludingImpairedFinancingReceivablesRecordedInvestment	14061682000	USD
CY2019Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	10220000	USD
CY2018Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	12536000	USD
CY2019Q4	cbsh	Accruing Restructured Loans AccruingRestructuredLoans	71512000	USD
CY2018Q4	cbsh	Accruing Restructured Loans AccruingRestructuredLoans	66080000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	81732000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	78616000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment	7054000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance	13738000	USD
CY2019Q4	cbsh	Impaired Financing Receivablewith No Related Allowance Allowance ImpairedFinancingReceivablewithNoRelatedAllowanceAllowance	0	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With Related Allowance Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment	74678000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance	76652000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	2746000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	81732000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Unpaid Principal Balance ImpairedFinancingReceivableUnpaidPrincipalBalance	90390000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	2746000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment	8725000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance	14477000	USD
CY2018Q4	cbsh	Impaired Financing Receivablewith No Related Allowance Allowance ImpairedFinancingReceivablewithNoRelatedAllowanceAllowance	0	USD
CY2018Q4	us-gaap	Impaired Financing Receivable With Related Allowance Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment	69891000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable With Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance	72597000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	2696000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	78616000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable Unpaid Principal Balance ImpairedFinancingReceivableUnpaidPrincipalBalance	87074000	USD
CY2018Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	2696000	USD
CY2019	cbsh	Financing Receivable Average Recorded Investment Nonaccrual Status FinancingReceivableAverageRecordedInvestmentNonaccrualStatus	11923000	USD
CY2018	cbsh	Financing Receivable Average Recorded Investment Nonaccrual Status FinancingReceivableAverageRecordedInvestmentNonaccrualStatus	9741000	USD
CY2019	cbsh	Financing Receivable Modifications Average Recorded Investment FinancingReceivableModificationsAverageRecordedInvestment	65211000	USD
CY2018	cbsh	Financing Receivable Modifications Average Recorded Investment FinancingReceivableModificationsAverageRecordedInvestment	89787000	USD
CY2019	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	77134000	USD
CY2018	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	99528000	USD
CY2019	us-gaap	Impaired Financing Receivable Interest Income Accrual Method ImpairedFinancingReceivableInterestIncomeAccrualMethod	4040000	USD
CY2018	us-gaap	Impaired Financing Receivable Interest Income Accrual Method ImpairedFinancingReceivableInterestIncomeAccrualMethod	3995000	USD
CY2017	us-gaap	Impaired Financing Receivable Interest Income Accrual Method ImpairedFinancingReceivableInterestIncomeAccrualMethod	5082000	USD
CY2019Q4	cbsh	Financing Receivable Recorded Investment Currentor Lessthan30days Past Due FinancingReceivableRecordedInvestmentCurrentorLessthan30daysPastDue	14627638000	USD
CY2019Q4	cbsh	Financing Receivable Recorded Investment Thirty To Eighty Nine Days Past Due FinancingReceivableRecordedInvestmentThirtyToEightyNineDaysPastDue	80100000	USD
CY2019Q4	us-gaap	Financing Receivable Recorded Investment90 Days Past Due And Still Accruing FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing	19859000	USD
CY2019Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	10220000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	14737817000	USD
CY2018Q4	cbsh	Financing Receivable Recorded Investment Currentor Lessthan30days Past Due FinancingReceivableRecordedInvestmentCurrentorLessthan30daysPastDue	14038417000	USD
CY2018Q4	cbsh	Financing Receivable Recorded Investment Thirty To Eighty Nine Days Past Due FinancingReceivableRecordedInvestmentThirtyToEightyNineDaysPastDue	72687000	USD
CY2018Q4	us-gaap	Financing Receivable Recorded Investment90 Days Past Due And Still Accruing FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing	16658000	USD
CY2018Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	12536000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	14140298000	USD
CY2019Q4	cbsh	Commercial Loan Portfolio Gross Carrying Amount CommercialLoanPortfolioGrossCarryingAmount	9298380000	USD
CY2018Q4	cbsh	Commercial Loan Portfolio Gross Carrying Amount CommercialLoanPortfolioGrossCarryingAmount	8851874000	USD
CY2019Q4	cbsh	Credit Quality Personal Real Estate Loans Excluded CreditQualityPersonalRealEstateLoansExcluded	198200000	USD
CY2018Q4	cbsh	Credit Quality Personal Real Estate Loans Excluded CreditQualityPersonalRealEstateLoansExcluded	201700000	USD
CY2019Q4	cbsh	Consumer Healthcare Loans Excluded ConsumerHealthcareLoansExcluded	199200000	USD
CY2018Q4	cbsh	Consumer Healthcare Loans Excluded ConsumerHealthcareLoansExcluded	170300000	USD
CY2019Q4	cbsh	Credit Quality Personal Banking Loan Table Percentage Loans Excluded CreditQualityPersonalBankingLoanTablePercentageLoansExcluded	0.08	Rate
CY2019Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	79450000	USD
CY2018Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	75839000	USD
CY2019Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	79450000	USD
CY2019Q4	cbsh	Financing Receivable Troubled Debt Restructurings That Subsequently Defaulted Recorded Investment FinancingReceivableTroubledDebtRestructuringsThatSubsequentlyDefaultedRecordedInvestment	1417000	USD
CY2019	cbsh	Effect On Interest Income Resulting From Modification To Credit Card Loans EffectOnInterestIncomeResultingFromModificationToCreditCardLoans	1200000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Impaired Commitment To Lend LoansAndLeasesReceivableImpairedCommitmentToLend	4700000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Impaired Commitment To Lend LoansAndLeasesReceivableImpairedCommitmentToLend	1800000	USD
CY2019Q4	us-gaap	Loans Held For Sale Fair Value Disclosure LoansHeldForSaleFairValueDisclosure	9200000	USD
CY2019Q4	cbsh	Unpaid Principal Balanceon Personal Real Estate Loans Heldfor Sale UnpaidPrincipalBalanceonPersonalRealEstateLoansHeldforSale	8900000	USD
CY2019Q4	cbsh	Student Loans Heldfor Sale Lowerof Costor Fair Value StudentLoansHeldforSaleLowerofCostorFairValue	4600000	USD
CY2019Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	365000	USD
CY2018Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	1400000	USD
CY2019Q4	us-gaap	Other Foreclosed Assets OtherForeclosedAssets	5500000	USD
CY2018Q4	us-gaap	Other Foreclosed Assets OtherForeclosedAssets	2000000.0	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	8571626000	USD
CY2018Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	8538041000	USD
CY2019Q4	us-gaap	Trading Securities TradingSecurities	28161000	USD
CY2018Q4	us-gaap	Trading Securities TradingSecurities	27059000	USD
CY2019Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	2929000	USD
CY2018Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	2585000	USD
CY2019Q4	cbsh	Equtiy Securitieswithout Readily Determinable Fair Values EqutiySecuritieswithoutReadilyDeterminableFairValues	1280000	USD
CY2018Q4	cbsh	Equtiy Securitieswithout Readily Determinable Fair Values EqutiySecuritieswithoutReadilyDeterminableFairValues	1824000	USD
CY2019Q4	us-gaap	Federal Reserve Bank Stock FederalReserveBankStock	33770000	USD
CY2018Q4	us-gaap	Federal Reserve Bank Stock FederalReserveBankStock	33498000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	10000000	USD
CY2018Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	10000000	USD
CY2019Q4	cbsh	Private Equity Investments PrivateEquityInvestments	94122000	USD
CY2018Q4	cbsh	Private Equity Investments PrivateEquityInvestments	85659000	USD
CY2019Q4	cbsh	Total Investment Securities TotalInvestmentSecurities	8741888000	USD
CY2018Q4	cbsh	Total Investment Securities TotalInvestmentSecurities	8698666000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	8435531000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	8571626000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	8435531000	USD
CY2019Q4	cbsh	Available For Sale Securities Gross Unreailzed Gainat Period End AvailableForSaleSecuritiesGrossUnreailzedGainatPeriodEnd	148959000	USD
CY2019Q4	cbsh	Available For Sale Securities Gross Unrealized Lossat Period End AvailableForSaleSecuritiesGrossUnrealizedLossatPeriodEnd	12864000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	8571626000	USD
CY2018Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	8602599000	USD
CY2018Q4	cbsh	Available For Sale Securities Gross Unreailzed Gainat Period End AvailableForSaleSecuritiesGrossUnreailzedGainatPeriodEnd	35266000	USD
CY2018Q4	cbsh	Available For Sale Securities Gross Unrealized Lossat Period End AvailableForSaleSecuritiesGrossUnrealizedLossatPeriodEnd	99824000	USD
CY2018Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	8538041000	USD
CY2019	cbsh	Percentage Decrease In Fair Value Below Amortized Cost PercentageDecreaseInFairValueBelowAmortizedCost	0.20
CY2019Q4	cbsh	Fair Value Securities On Other Than Temporary Impairment Watch List FairValueSecuritiesOnOtherThanTemporaryImpairmentWatchList	51600000	USD
CY2018Q4	cbsh	Fair Value Securities On Other Than Temporary Impairment Watch List FairValueSecuritiesOnOtherThanTemporaryImpairmentWatchList	57700000	USD
CY2018Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	14092000	USD
CY2017Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	14199000	USD
CY2016Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	14080000	USD
CY2019	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Additions No Previous Impairment OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsNoPreviousImpairment	48000	USD
CY2018	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Additions No Previous Impairment OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsNoPreviousImpairment	58000	USD
CY2017	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Additions No Previous Impairment OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsNoPreviousImpairment	111000	USD
CY2019	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Additions Additional Credit Losses OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsAdditionalCreditLosses	85000	USD
CY2018	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Additions Additional Credit Losses OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsAdditionalCreditLosses	10000	USD
CY2017	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Additions Additional Credit Losses OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsAdditionalCreditLosses	274000	USD
CY2019	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Reductions Cash Flows OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsReductionsCashFlows	950000	USD
CY2018	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Reductions Cash Flows OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsReductionsCashFlows	175000	USD
CY2017	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Reductions Cash Flows OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsReductionsCashFlows	266000	USD
CY2019Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	13275000	USD
CY2018Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	14092000	USD
CY2017Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	14199000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	1136297000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	9413000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	517817000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	3451000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	1654114000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	12864000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	1213809000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	11098000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	4221687000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	88726000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	5435496000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	99824000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	1700000000	USD
CY2018Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	5400000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	12900000	USD
CY2019	cbsh	Af Ssecuritiesinlosspositionatperiodendchangeinunrealizedloss AFSsecuritiesinlosspositionatperiodendchangeinunrealizedloss	-87000000.0	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	402103000	USD
CY2018	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	667227000	USD
CY2017	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	779793000	USD
CY2019	cbsh	Proceedsfromsaleofequitysecurities Proceedsfromsaleofequitysecurities	3856000	USD
CY2018	cbsh	Proceedsfromsaleofequitysecurities Proceedsfromsaleofequitysecurities	41637000	USD
CY2017	cbsh	Proceedsfromsaleofequitysecurities Proceedsfromsaleofequitysecurities	10953000	USD
CY2019	cbsh	Proceeds From Sale Of Other Securities ProceedsFromSaleOfOtherSecurities	7244000	USD
CY2018	cbsh	Proceeds From Sale Of Other Securities ProceedsFromSaleOfOtherSecurities	0	USD
CY2017	cbsh	Proceeds From Sale Of Other Securities ProceedsFromSaleOfOtherSecurities	1634000	USD
CY2019	cbsh	Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities	413203000	USD
CY2018	cbsh	Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities	708864000	USD
CY2017	cbsh	Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities	792380000	USD
CY2019	us-gaap	Gain Loss On Investments GainLossOnInvestments	3626000	USD
CY2018	us-gaap	Gain Loss On Investments GainLossOnInvestments	-488000	USD
CY2017	us-gaap	Gain Loss On Investments GainLossOnInvestments	25051000	USD
CY2019Q4	cbsh	Investment Securities Pledged At Fair Value InvestmentSecuritiesPledgedAtFairValue	4300000000	USD
CY2019Q4	us-gaap	Financial Instruments Owned And Pledged As Collateral Amount Eligible To Be Repledged By Counterparty FinancialInstrumentsOwnedAndPledgedAsCollateralAmountEligibleToBeRepledgedByCounterparty	204900000	USD
CY2019Q4	cbsh	Investments Exceeding Ten Percent Of Stockholders Equity InvestmentsExceedingTenPercentOfStockholdersEquity	0	Investments_In_Single_Issuer
CY2019Q4	cbsh	Percentage Of Stockholders Equity Of Which No Investment From Single Issuer Exceeds PercentageOfStockholdersEquityOfWhichNoInvestmentFromSingleIssuerExceeds	0.10
CY2019Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	923097000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	863779000	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	552460000	USD
CY2018Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	530660000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	370637000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	333119000	USD
CY2019	us-gaap	Depreciation Depreciation	30800000	USD
CY2018	us-gaap	Depreciation Depreciation	28600000	USD
CY2017	us-gaap	Depreciation Depreciation	29100000	USD
CY2019	us-gaap	Cost Of Property Repairs And Maintenance CostOfPropertyRepairsAndMaintenance	17000000.0	USD
CY2018	us-gaap	Cost Of Property Repairs And Maintenance CostOfPropertyRepairsAndMaintenance	16900000	USD
CY2017	us-gaap	Cost Of Property Repairs And Maintenance CostOfPropertyRepairsAndMaintenance	16400000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	44212000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	34351000	USD
CY2019Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	327000	USD
CY2019Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	9534000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	41609000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	32815000	USD
CY2018Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	0	USD
CY2018Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	8794000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	138921000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	138921000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1500000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1300000	USD
CY2017	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1300000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	1507000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	1286000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	1099000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	919000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	770000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	26300000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	27000000.0	USD
CY2019	us-gaap	Lease Cost LeaseCost	7300000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	5913000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	5001000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	4304000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	3802000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	2530000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	12600000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	34150000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	7126000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	27024000	USD
CY2019Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance Sheet Amount UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount	6500000	USD
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P11Y8M12D
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0367
	us-gaap	Operating Lease Payments OperatingLeasePayments	5989000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	3958000	USD
CY2018	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	7700000	USD
CY2017	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	7300000	USD
CY2019Q4	cbsh	Lessor Total Paymentstobe Received Three Years LessorTotalPaymentstobeReceivedThreeYears	150603000	USD
CY2019Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Payments To Be Received Four Years SalesTypeAndDirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedFourYears	92813000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received Four Years LessorOperatingLeasePaymentsToBeReceivedFourYears	5536000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	5763000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	4817000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	4055000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	3598000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	3273000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	15161000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	36667000	USD
CY2019	us-gaap	Sales Type And Direct Financing Leases Profit Loss SalesTypeAndDirectFinancingLeasesProfitLoss	24062000	USD
CY2019	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	7951000	USD
CY2019	us-gaap	Lease Income LeaseIncome	32013000	USD
CY2019Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable SalesTypeAndDirectFinancingLeasesLeaseReceivable	738809000	USD
CY2019Q4	cbsh	Salestypeand Direct Financing Leases Unguaranteed Residual Asset SalestypeandDirectFinancingLeasesUnguaranteedResidualAsset	53408000	USD
CY2019Q4	us-gaap	Net Investment In Lease NetInvestmentInLease	792217000	USD
CY2019Q4	us-gaap	Deferred Costs Leasing Net DeferredCostsLeasingNet	3609000	USD
CY2019Q4	us-gaap	Net Investment In Direct Financing And Sales Type Leases NetInvestmentInDirectFinancingAndSalesTypeLeases	795826000	USD
CY2019Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Payments To Be Received Next Twelve Months SalesTypeAndDirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedNextTwelveMonths	224297000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received Next Twelve Months LessorOperatingLeasePaymentsToBeReceivedNextTwelveMonths	7564000	USD
CY2019Q4	cbsh	Lessor Total Paymentstobe Received Next Twelve Months LessorTotalPaymentstobeReceivedNextTwelveMonths	231861000	USD
CY2019Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Payments To Be Received Two Years SalesTypeAndDirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedTwoYears	177143000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received Two Years LessorOperatingLeasePaymentsToBeReceivedTwoYears	7511000	USD
CY2019Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Payments To Be Received Five Years SalesTypeAndDirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedFiveYears	58773000	USD
CY2019Q4	cbsh	Lessor Total Paymentstobe Received Four Years LessorTotalPaymentstobeReceivedFourYears	98349000	USD
CY2019Q4	cbsh	Lessor Total Paymentstobe Received Two Years LessorTotalPaymentstobeReceivedTwoYears	184654000	USD
CY2019Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Payments To Be Received Three Years SalesTypeAndDirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedThreeYears	136787000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received Three Years LessorOperatingLeasePaymentsToBeReceivedThreeYears	13816000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received Five Years LessorOperatingLeasePaymentsToBeReceivedFiveYears	4811000	USD
CY2019Q4	cbsh	Lessor Total Paymentstobe Received Five Years LessorTotalPaymentstobeReceivedFiveYears	63584000	USD
CY2019Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Payments To Be Received Thereafter SalesTypeAndDirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedThereafter	114188000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received Thereafter LessorOperatingLeasePaymentsToBeReceivedThereafter	8643000	USD
CY2019Q4	cbsh	Lessor Total Paymentstobe Received Thereafter LessorTotalPaymentstobeReceivedThereafter	122831000	USD
CY2019Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Payments To Be Received SalesTypeAndDirectFinancingLeasesLeaseReceivablePaymentsToBeReceived	804001000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received LessorOperatingLeasePaymentsToBeReceived	47881000	USD
CY2019Q4	cbsh	Lessor Total Paymentstobe Received LessorTotalPaymentstobeReceived	851882000	USD
CY2019Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Undiscounted Excess Amount SalesTypeAndDirectFinancingLeasesLeaseReceivableUndiscountedExcessAmount	65192000	USD
CY2019Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable SalesTypeAndDirectFinancingLeasesLeaseReceivable	738809000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	1727042000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	229487000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	27205000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	14387000	USD
CY2019Q4	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	9838000	USD
CY2019Q4	us-gaap	Time Deposit Maturities After Year Five TimeDepositMaturitiesAfterYearFive	53000	USD
CY2019Q4	us-gaap	Time Deposits TimeDeposits	2008012000	USD
CY2019Q4	cbsh	Contractual Maturities Certificates Of Deposit Under100000 Three Months Or Less ContractualMaturitiesCertificatesOfDepositUnder100000ThreeMonthsOrLess	117635000	USD
CY2019Q4	cbsh	Contractual Maturities Certificates Of Deposit Over100000 Three Months Or Less ContractualMaturitiesCertificatesOfDepositOver100000ThreeMonthsOrLess	632064000	USD
CY2019Q4	cbsh	Contractual Maturities Time Deposits Three Months Or Less Net ContractualMaturitiesTimeDepositsThreeMonthsOrLessNet	749699000	USD
CY2019Q4	cbsh	Contractual Maturities Certificates Of Deposit Under100000 Three Months Through Six Months ContractualMaturitiesCertificatesOfDepositUnder100000ThreeMonthsThroughSixMonths	144309000	USD
CY2019Q4	cbsh	Contractual Maturities Certificates Of Deposit Over100000 Three Months Through Six Months ContractualMaturitiesCertificatesOfDepositOver100000ThreeMonthsThroughSixMonths	286240000	USD
CY2019Q4	cbsh	Contractual Maturities Time Deposits Three Months Through Six Months Net ContractualMaturitiesTimeDepositsThreeMonthsThroughSixMonthsNet	430549000	USD
CY2019Q4	cbsh	Contractual Maturities Certificates Of Deposit Under100000 Six Months Through Twelve Months ContractualMaturitiesCertificatesOfDepositUnder100000SixMonthsThroughTwelveMonths	223756000	USD
CY2019Q4	cbsh	Contractual Maturities Certificates Of Deposit Over100000 Six Months Through Twelve Months ContractualMaturitiesCertificatesOfDepositOver100000SixMonthsThroughTwelveMonths	323038000	USD
CY2019Q4	cbsh	Contractual Maturities Time Deposits Six Months Through Twelve Months Net ContractualMaturitiesTimeDepositsSixMonthsThroughTwelveMonthsNet	546794000	USD
CY2017	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	96889000	USD
CY2019Q4	cbsh	Contractual Maturities Certificates Of Deposit Under100000 After Twelve Months ContractualMaturitiesCertificatesOfDepositUnder100000AfterTwelveMonths	140457000	USD
CY2019Q4	cbsh	Contractual Maturities Certificates Of Deposit Over100000 After Twelve Months ContractualMaturitiesCertificatesOfDepositOver100000AfterTwelveMonths	140513000	USD
CY2019Q4	cbsh	Contractual Maturities Time Deposits After Twelve Months Net ContractualMaturitiesTimeDepositsAfterTwelveMonthsNet	280970000	USD
CY2019Q4	cbsh	Certificates Of Deposit Under100000 CertificatesOfDepositUnder100000	626157000	USD
CY2019Q4	cbsh	Certificates Of Deposit Over100000 CertificatesOfDepositOver100000	1381855000	USD
CY2019Q4	us-gaap	Time Deposits TimeDeposits	2008012000	USD
CY2019Q4	cbsh	Aggregateamountoftimeopenandcertificatesofdepositthatexceedthe250000 Fdi Cinsurancelimit Aggregateamountoftimeopenandcertificatesofdepositthatexceedthe250000FDICinsurancelimit	1100000000	USD
CY2019Q4	cbsh	Shorttermrepurchaseagreementcomprisedofnoninsuredcustomerfunds Shorttermrepurchaseagreementcomprisedofnoninsuredcustomerfunds	1800000000	USD
CY2019Q4	cbsh	Federal Home Loan Bank Letters Of Credit Issued FederalHomeLoanBankLettersOfCreditIssued	396600000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	82556000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	11388000	USD
CY2019	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	93944000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	12323000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	2807000	USD
CY2019	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	15130000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	94879000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	14195000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	109074000	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	90390000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	3220000	USD
CY2018	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	93610000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	10223000	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	2116000	USD
CY2018	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	12339000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	100613000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	5336000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	105949000	USD
CY2017	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	89154000	USD
CY2017	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	12190000	USD
CY2017	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	101344000	USD
CY2017	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	1427000	USD
CY2017	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	9162000	USD
CY2017	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	7735000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	13617000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	110506000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax	50163000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax	-18634000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax	2104000	USD
CY2019	cbsh	Componentsofincome Tax Recorded Directlyto Equity Changein Fair Valueof Cash Flow Hedge ComponentsofincomeTaxRecordedDirectlytoEquityChangeinFairValueofCashFlowHedge	7818000	USD
CY2018	cbsh	Componentsofincome Tax Recorded Directlyto Equity Changein Fair Valueof Cash Flow Hedge ComponentsofincomeTaxRecordedDirectlytoEquityChangeinFairValueofCashFlowHedge	2286000	USD
CY2017	cbsh	Componentsofincome Tax Recorded Directlyto Equity Changein Fair Valueof Cash Flow Hedge ComponentsofincomeTaxRecordedDirectlytoEquityChangeinFairValueofCashFlowHedge	0	USD
CY2019	cbsh	Income Tax Expense Accumulated Pension Benefit Loss IncomeTaxExpenseAccumulatedPensionBenefitLoss	389000	USD
CY2018	cbsh	Income Tax Expense Accumulated Pension Benefit Loss IncomeTaxExpenseAccumulatedPensionBenefitLoss	222000	USD
CY2017	cbsh	Income Tax Expense Accumulated Pension Benefit Loss IncomeTaxExpenseAccumulatedPensionBenefitLoss	-184000	USD
CY2019	us-gaap	Income Tax Effects Allocated Directly To Equity IncomeTaxEffectsAllocatedDirectlyToEquity	58370000	USD
CY2018	us-gaap	Income Tax Effects Allocated Directly To Equity IncomeTaxEffectsAllocatedDirectlyToEquity	-16126000	USD
CY2017	us-gaap	Income Tax Effects Allocated Directly To Equity IncomeTaxEffectsAllocatedDirectlyToEquity	1920000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	39130000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	39169000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Unrealized Losses On Availablefor Sale Securities Gross DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross	0	USD
CY2018Q4	us-gaap	Deferred Tax Assets Unrealized Losses On Availablefor Sale Securities Gross DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross	16140000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	7554000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	7609000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits	6662000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits	5911000	USD
CY2019Q4	cbsh	Deferredtaxassetsunearnedincome Deferredtaxassetsunearnedincome	5053000	USD
CY2018Q4	cbsh	Deferredtaxassetsunearnedincome Deferredtaxassetsunearnedincome	4125000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	4270000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	2152000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	4057000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	4640000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	66726000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	79746000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	68814000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	55738000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other Comprehensive Income DeferredTaxLiabilitiesOtherComprehensiveIncome	34024000	USD
CY2019	cbsh	Effective Income Tax Rate Reconciliation Sharebased Award Payments Amount EffectiveIncomeTaxRateReconciliationSharebasedAwardPaymentsAmount	-3337000	USD
CY2018	cbsh	Effective Income Tax Rate Reconciliation Sharebased Award Payments Amount EffectiveIncomeTaxRateReconciliationSharebasedAwardPaymentsAmount	-3928000	USD
CY2017	cbsh	Effective Income Tax Rate Reconciliation Sharebased Award Payments Amount EffectiveIncomeTaxRateReconciliationSharebasedAwardPaymentsAmount	-6613000	USD
CY2019	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	67000	USD
CY2018	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-1662000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Other Comprehensive Income DeferredTaxLiabilitiesOtherComprehensiveIncome	0	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	17202000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	14207000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Derivatives DeferredTaxLiabilitiesDerivatives	9015000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Derivatives DeferredTaxLiabilitiesDerivatives	2104000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	6491000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	5973000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	7331000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	5309000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	142877000	USD
CY2018Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	83331000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	76151000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	3585000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21	Rate
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35	Rate
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	111364000	USD
CY2018	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	113293000	USD
CY2017	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	150461000	USD
CY2019	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	10973000	USD
CY2018	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	11502000	USD
CY2017	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	20295000	USD
CY2019	cbsh	Effective Income Tax Rate Reconciliation Contributionof Appreciated Securities Amount EffectiveIncomeTaxRateReconciliationContributionofAppreciatedSecuritiesAmount	0	USD
CY2018	cbsh	Effective Income Tax Rate Reconciliation Contributionof Appreciated Securities Amount EffectiveIncomeTaxRateReconciliationContributionofAppreciatedSecuritiesAmount	0	USD
CY2017	cbsh	Effective Income Tax Rate Reconciliation Contributionof Appreciated Securities Amount EffectiveIncomeTaxRateReconciliationContributionofAppreciatedSecuritiesAmount	10864000	USD
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	11953000	USD
CY2018	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	9748000	USD
CY2017	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	5955000	USD
CY2019	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	0	USD
CY2018	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	0	USD
CY2017	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	-6753000	USD
CY2017	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-1385000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	109074000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	105949000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	110506000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1400000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1300000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	1100000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	993000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1257000	USD
CY2017	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	3826000	USD
CY2019	us-gaap	Defined Benefit Plan Expected Return On Plan Assets DefinedBenefitPlanExpectedReturnOnPlanAssets	4842000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1208000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	18000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	31000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	4000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	0	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	361000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	322000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	260000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	304000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1372000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1257000	USD
CY2019	us-gaap	Employee Benefits And Share Based Compensation EmployeeBenefitsAndShareBasedCompensation	76058000	USD
CY2018	us-gaap	Employee Benefits And Share Based Compensation EmployeeBenefitsAndShareBasedCompensation	71297000	USD
CY2017	us-gaap	Employee Benefits And Share Based Compensation EmployeeBenefitsAndShareBasedCompensation	67376000	USD
CY2017	cbsh	Definedbenefitplandiscretionarycontributionbyemployer Definedbenefitplandiscretionarycontributionbyemployer	5500000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Expected Future Employer Contributions Next Fiscal Year DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear	0	USD
CY2019	cbsh	Cerp Contributions CerpContributions	25000	USD
CY2018	cbsh	Cerp Contributions CerpContributions	24000	USD
CY2017	cbsh	Cerp Contributions CerpContributions	439000	USD
CY2019	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	607000	USD
CY2018	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	651000	USD
CY2017	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	621000	USD
CY2019	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	4198000	USD
CY2018	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	3756000	USD
CY2018	us-gaap	Defined Benefit Plan Expected Return On Plan Assets DefinedBenefitPlanExpectedReturnOnPlanAssets	5255000	USD
CY2017	us-gaap	Defined Benefit Plan Expected Return On Plan Assets DefinedBenefitPlanExpectedReturnOnPlanAssets	5785000	USD
CY2019	us-gaap	Defined Benefit Plan Amortization Of Prior Service Cost Credit DefinedBenefitPlanAmortizationOfPriorServiceCostCredit	-271000	USD
CY2018	us-gaap	Defined Benefit Plan Amortization Of Prior Service Cost Credit DefinedBenefitPlanAmortizationOfPriorServiceCostCredit	-271000	USD
CY2017	us-gaap	Defined Benefit Plan Amortization Of Prior Service Cost Credit DefinedBenefitPlanAmortizationOfPriorServiceCostCredit	-271000	USD
CY2019	us-gaap	Defined Benefit Plan Amortization Of Gains Losses DefinedBenefitPlanAmortizationOfGainsLosses	-2288000	USD
CY2018	us-gaap	Defined Benefit Plan Amortization Of Gains Losses DefinedBenefitPlanAmortizationOfGainsLosses	-2267000	USD
CY2017	us-gaap	Defined Benefit Plan Amortization Of Gains Losses DefinedBenefitPlanAmortizationOfGainsLosses	-2313000	USD
CY2019	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	1980000	USD
CY2018	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	1148000	USD
CY2017	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	704000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	112063000	USD
CY2017Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	120667000	USD
CY2019	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	607000	USD
CY2018	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	651000	USD
CY2019	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	4198000	USD
CY2018	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	3756000	USD
CY2019	us-gaap	Defined Benefit Plan Benefit Obligation Benefits Paid DefinedBenefitPlanBenefitObligationBenefitsPaid	7016000	USD
CY2018	us-gaap	Defined Benefit Plan Benefit Obligation Benefits Paid DefinedBenefitPlanBenefitObligationBenefitsPaid	6622000	USD
CY2019	us-gaap	Defined Benefit Plan Actuarial Gain Loss DefinedBenefitPlanActuarialGainLoss	-10750000	USD
CY2018	us-gaap	Defined Benefit Plan Actuarial Gain Loss DefinedBenefitPlanActuarialGainLoss	6389000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	120602000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	112063000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	99418000	USD
CY2017Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	108260000	USD
CY2019	us-gaap	Defined Benefit Plan Actual Return On Plan Assets DefinedBenefitPlanActualReturnOnPlanAssets	15129000	USD
CY2018	us-gaap	Defined Benefit Plan Actual Return On Plan Assets DefinedBenefitPlanActualReturnOnPlanAssets	-2244000	USD
CY2019	us-gaap	Defined Benefit Plan Contributions By Employer DefinedBenefitPlanContributionsByEmployer	25000	USD
CY2018	us-gaap	Defined Benefit Plan Contributions By Employer DefinedBenefitPlanContributionsByEmployer	24000	USD
CY2019	us-gaap	Defined Benefit Plan Plan Assets Benefits Paid DefinedBenefitPlanPlanAssetsBenefitsPaid	7016000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Funded Status Of Plan DefinedBenefitPlanFundedStatusOfPlan	-13046000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	99418000	USD
CY2018	us-gaap	Defined Benefit Plan Plan Assets Benefits Paid DefinedBenefitPlanPlanAssetsBenefitsPaid	6622000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	107556000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Accumulated Benefit Obligation DefinedBenefitPlanAccumulatedBenefitObligation	120600000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Accumulated Benefit Obligation DefinedBenefitPlanAccumulatedBenefitObligation	112100000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Funded Status Of Plan DefinedBenefitPlanFundedStatusOfPlan	-12645000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Net Prior Service Cost Credit Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax	1265000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Net Prior Service Cost Credit Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax	1535000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Net Gains Losses Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax	30516000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Net Gains Losses Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax	32342000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax	-29251000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax	-30807000	USD
CY2019Q4	cbsh	Cumulative Employer Contributions In Excess Of Net Periodic Benefit Cost CumulativeEmployerContributionsInExcessOfNetPeriodicBenefitCost	16205000	USD
CY2018Q4	cbsh	Cumulative Employer Contributions In Excess Of Net Periodic Benefit Cost CumulativeEmployerContributionsInExcessOfNetPeriodicBenefitCost	18162000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Amounts Recognized In Balance Sheet DefinedBenefitPlanAmountsRecognizedInBalanceSheet	-13046000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Amounts Recognized In Balance Sheet DefinedBenefitPlanAmountsRecognizedInBalanceSheet	-12645000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	461000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	1110000	USD
CY2019	us-gaap	Defined Benefit Plan Amortization Of Gains Losses DefinedBenefitPlanAmortizationOfGainsLosses	-2288000	USD
CY2018	us-gaap	Defined Benefit Plan Amortization Of Gains Losses DefinedBenefitPlanAmortizationOfGainsLosses	-2267000	USD
CY2019	us-gaap	Defined Benefit Plan Amortization Of Prior Service Cost Credit DefinedBenefitPlanAmortizationOfPriorServiceCostCredit	-271000	USD
CY2018	us-gaap	Defined Benefit Plan Amortization Of Prior Service Cost Credit DefinedBenefitPlanAmortizationOfPriorServiceCostCredit	-271000	USD
CY2019	us-gaap	Defined Benefit Plan Amounts Recognized In Other Comprehensive Income Loss Net Gain Loss Before Tax DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeLossNetGainLossBeforeTax	-1556000	USD
CY2018	us-gaap	Defined Benefit Plan Amounts Recognized In Other Comprehensive Income Loss Net Gain Loss Before Tax DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeLossNetGainLossBeforeTax	-886000	USD
CY2019Q4	cbsh	Defined Benefit Plan Amount Recognized In Net Periodic Pension Cost And Other Comprehensive Income DefinedBenefitPlanAmountRecognizedInNetPeriodicPensionCostAndOtherComprehensiveIncome	-424000	USD
CY2018Q4	cbsh	Defined Benefit Plan Amount Recognized In Net Periodic Pension Cost And Other Comprehensive Income DefinedBenefitPlanAmountRecognizedInNetPeriodicPensionCostAndOtherComprehensiveIncome	-262000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Expected Amortization Next Fiscal Year DefinedBenefitPlanExpectedAmortizationNextFiscalYear	1900000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate	0.0307	Rate
CY2018Q4	us-gaap	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate	0.0414	Rate
CY2017Q4	us-gaap	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate	0.0357	Rate
CY2019Q4	cbsh	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Assumed Credit On Cash Balance Accounts DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationAssumedCreditOnCashBalanceAccounts	0.0500	Rate
CY2018Q4	cbsh	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Assumed Credit On Cash Balance Accounts DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationAssumedCreditOnCashBalanceAccounts	0.0500	Rate
CY2017Q4	cbsh	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Assumed Credit On Cash Balance Accounts DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationAssumedCreditOnCashBalanceAccounts	0.0500	Rate
CY2019	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate	0.0413	Rate
CY2018	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate	0.0357	Rate
CY2017	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate	0.0395	Rate
CY2019	cbsh	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Effective Rateof Interest DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostEffectiveRateofInterest	0.0381	Rate
CY2018	cbsh	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Effective Rateof Interest DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostEffectiveRateofInterest	0.0328	Rate
CY2017	cbsh	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Effective Rateof Interest DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostEffectiveRateofInterest	0.0328	Rate
CY2019	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Expected Long Term Return On Assets DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets	0.0500	Rate
CY2018	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Expected Long Term Return On Assets DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets	0.0500	Rate
CY2017	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Expected Long Term Return On Assets DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets	0.0600	Rate
CY2019	cbsh	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Assumed Credit On Cash Balance Accounts DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostAssumedCreditOnCashBalanceAccounts	0.0500	Rate
CY2018	cbsh	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Assumed Credit On Cash Balance Accounts DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostAssumedCreditOnCashBalanceAccounts	0.0500	Rate
CY2017	cbsh	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Assumed Credit On Cash Balance Accounts DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostAssumedCreditOnCashBalanceAccounts	0.0500	Rate
CY2019	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Expected Long Term Return On Assets DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets	0.050	Rate
CY2019	cbsh	Annualized Return For Pension Plan AnnualizedReturnForPensionPlan	0.073	Rate
CY2019	cbsh	Rate Of Return Of Pension Plan RateOfReturnOfPensionPlan	0.148	Rate
CY2018	cbsh	Rate Of Return Of Pension Plan RateOfReturnOfPensionPlan	-0.017	Rate
CY2019	cbsh	Pension Expense Expected In Next Fiscal Year PensionExpenseExpectedInNextFiscalYear	402000	USD
CY2019	us-gaap	Pension Expense PensionExpense	2000000.0	USD
CY2019Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Next Twelve Months DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths	7281000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Two DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo	7430000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Three DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree	7409000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Four DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour	7467000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Five DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive	7371000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Five Fiscal Years Thereafter DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter	35721000	USD
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	2249326	shares
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	13900000	USD
CY2018	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	12800000	USD
CY2017	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	12100000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	3000000.0	USD
CY2018	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	3200000	USD
CY2017	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	4500000	USD
CY2018Q4	cbsh	Nonvested Share Awards Balances NonvestedShareAwardsBalances	1239970	shares
CY2017Q4	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Nonvested Share Awards Weighted Average Grant Date Unit Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsNonvestedShareAwardsWeightedAverageGrantDateUnitFairValue	41.18
CY2019	cbsh	Nonvested Share Awards Granted In Period NonvestedShareAwardsGrantedInPeriod	217182	shares
CY2018	cbsh	Share Based Compensation Granted Nonvested Share Award Weighted Average Grant Date Fair Value ShareBasedCompensationGrantedNonvestedShareAwardWeightedAverageGrantDateFairValue	58.82
CY2019	cbsh	Nonvested Share Awards Vested In Period NonvestedShareAwardsVestedInPeriod	339618	shares
CY2018	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Nonvested Share Awards Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsNonvestedShareAwardsVestedInPeriodWeightedAverageGrantDateFairValue	31.33
CY2019	cbsh	Nonvested Share Awards Forfeited In Period NonvestedShareAwardsForfeitedInPeriod	13323	shares
CY2018	cbsh	Share Based Compensation Forfeited Nonvested Share Award Weighted Average Grant Date Fair Value ShareBasedCompensationForfeitedNonvestedShareAwardWeightedAverageGrantDateFairValue	47.41
CY2019Q4	cbsh	Nonvested Share Awards Balances NonvestedShareAwardsBalances	1104211	shares
CY2018Q4	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Nonvested Share Awards Weighted Average Grant Date Unit Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsNonvestedShareAwardsWeightedAverageGrantDateUnitFairValue	47.57
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	19900000	USD
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	21500000	USD
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	23800000	USD
CY2018Q4	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumber	1119405	shares
CY2018Q4	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePrice	38.30
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	196129	shares
CY2019	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageExercisePrice	58.82
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	5935	shares
CY2019	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageExercisePrice	49.67
CY2019	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Expired In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpiredInPeriod	1917	shares
CY2019	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Expired In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpiredInPeriodWeightedAverageExercisePrice	37.00
CY2019	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Exercised In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisedInPeriod	257866	shares
CY2019	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Exercised In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisedInPeriodWeightedAverageExercisePrice	32.30
CY2019Q4	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumber	1049816	shares
CY2019Q4	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePrice	43.55
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Outstanding Weighted Average Remaining Contractual Terms ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms	P6Y7M6D
CY2019Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Equity Instruments Other Than Options Aggregate Intrinsic Value Outstanding SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding	25601000	USD
CY2019Q4	cbsh	Stock Appreciation Rights Activity Number Of Shares Exercisable StockAppreciationRightsActivityNumberOfSharesExercisable	557763	shares
CY2019Q4	cbsh	Stock Appreciation Rights Weighted Average Exercise Price Stock Options Exercisable StockAppreciationRightsWeightedAverageExercisePriceStockOptionsExercisable	36.16
CY2019	cbsh	Stock Appreciation Rights Weighted Average Remaining Contractual Term Options Exercisable StockAppreciationRightsWeightedAverageRemainingContractualTermOptionsExercisable	P5Y3M18D
CY2019Q4	cbsh	Stock Appreciation Rights Aggregate Intrinsic Value Options Exercisable StockAppreciationRightsAggregateIntrinsicValueOptionsExercisable	17728000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	11.35
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	11.28
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	10.83
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.017
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.016	Rate
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.016	Rate
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.198
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.206	Rate
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.211	Rate
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.026
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.027	Rate
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.024	Rate
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P6Y
CY2018	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P6Y7M6D
CY2017	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P7Y
CY2019Q4	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises And Stock Appreciation Rights Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesAndStockAppreciationRightsExercisesInPeriodTotalIntrinsicValue	7109000	USD
CY2018Q4	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises And Stock Appreciation Rights Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesAndStockAppreciationRightsExercisesInPeriodTotalIntrinsicValue	9632000	USD
CY2017Q4	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises And Stock Appreciation Rights Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesAndStockAppreciationRightsExercisesInPeriodTotalIntrinsicValue	9310000	USD
CY2019Q4	cbsh	Tax Benefit Realized From Options And Stock Appreciation Rights Exercised TaxBenefitRealizedFromOptionsAndStockAppreciationRightsExercised	1385000	USD
CY2018Q4	cbsh	Tax Benefit Realized From Options And Stock Appreciation Rights Exercised TaxBenefitRealizedFromOptionsAndStockAppreciationRightsExercised	1928000	USD
CY2017Q4	cbsh	Tax Benefit Realized From Options And Stock Appreciation Rights Exercised TaxBenefitRealizedFromOptionsAndStockAppreciationRightsExercised	2698000	USD
CY2019Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	27700000	USD
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1	P3Y
CY2018	cbsh	Common Stock Dividend Rate Percentage CommonStockDividendRatePercentage	0.05
CY2019	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Before Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax	-6158000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-64669000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Reclassifications Before Tax OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax	227325000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	233483000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	58370000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	175113000	USD
CY2019	cbsh	Reclassification Where Impairment Was Not Previously Recognized ReclassificationWhereImpairmentWasNotPreviouslyRecognized	0	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	110444000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	14108000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Before Reclassifications Before Tax OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax	-66892000	USD
CY2018	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Before Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax	-2377000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-64515000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-16126000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-48389000	USD
CY2018	cbsh	Reclassification Where Impairment Was Not Previously Recognized ReclassificationWhereImpairmentWasNotPreviouslyRecognized	0	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-64669000	USD
CY2019	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	3	Operating_Segments
CY2019	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	821293000	USD
CY2019	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	50438000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	524703000	USD
CY2019	us-gaap	Gain Loss On Investments GainLossOnInvestments	3626000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	767398000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	531786000	USD
CY2018	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	823825000	USD
CY2018	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	42694000	USD
CY2018	us-gaap	Noninterest Income NoninterestIncome	501341000	USD
CY2018	us-gaap	Gain Loss On Investments GainLossOnInvestments	-488000	USD
CY2018	us-gaap	Noninterest Expense NoninterestExpense	737821000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	544163000	USD
CY2017	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	733679000	USD
CY2017	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	45244000	USD
CY2017	us-gaap	Noninterest Income NoninterestIncome	461263000	USD
CY2017	us-gaap	Gain Loss On Investments GainLossOnInvestments	25051000	USD
CY2017	us-gaap	Noninterest Expense NoninterestExpense	744343000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	430406000	USD
CY2018Q4	cbsh	Segment Reporting Information Average Deposits SegmentReportingInformationAverageDeposits	20131252000	USD
CY2019Q4	cbsh	Average Assets AverageAssets	25213525000	USD
CY2019Q4	cbsh	Average Loan Portfolio Including Held For Sale AverageLoanPortfolioIncludingHeldForSale	14243214000	USD
CY2019Q4	cbsh	Segment Reporting Information Average Goodwill And Other Intangible Assets SegmentReportingInformationAverageGoodwillAndOtherIntangibleAssets	147910000	USD
CY2019Q4	cbsh	Segment Reporting Information Average Deposits SegmentReportingInformationAverageDeposits	19909891000	USD
CY2018Q4	cbsh	Average Assets AverageAssets	24666235000	USD
CY2018Q4	cbsh	Average Loan Portfolio Including Held For Sale AverageLoanPortfolioIncludingHeldForSale	13945572000	USD
CY2018Q4	cbsh	Segment Reporting Information Average Goodwill And Other Intangible Assets SegmentReportingInformationAverageGoodwillAndOtherIntangibleAssets	147108000	USD
CY2019	cbsh	Common Stock Dividend Rate Percentage CommonStockDividendRatePercentage	0.05
CY2019Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	5
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	356000	shares
CY2018	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	235000	shares
CY2017	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	167000	shares
CY2019Q3	cbsh	Accelerated Share Repurchase Program Repurchase Amount AcceleratedShareRepurchaseProgramRepurchaseAmount	150000000.0	USD
CY2019Q3	cbsh	Shares Received Under Accelerated Share Repurchase Program SharesReceivedUnderAcceleratedShareRepurchaseProgram	1994327	shares
CY2019Q3	cbsh	Percentageof Total Sharestobe Delivered PercentageofTotalSharestobeDelivered	0.75
CY2019Q4	cbsh	Shares Received Under Accelerated Share Repurchase Program SharesReceivedUnderAcceleratedShareRepurchaseProgram	438009	shares
CY2018Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	120000000	shares
CY2019Q2	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	140000000	shares
CY2019Q4	cbsh	Depositarysharesissued Depositarysharesissued	6000000	shares
CY2014Q2	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	6000	shares
CY2014Q2	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	1.00
CY2019Q4	us-gaap	Preferred Stock Liquidation Preference Value PreferredStockLiquidationPreferenceValue	150000000.0	USD
CY2019Q4	us-gaap	Preferred Stock Liquidation Preference PreferredStockLiquidationPreference	25
CY2019Q4	us-gaap	Stock Repurchase Program Number Of Shares Authorized To Be Repurchased StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased	5000000	shares
CY2019Q4	us-gaap	Stock Repurchase Program Remaining Number Of Shares Authorized To Be Repurchased StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased	4430958	shares
CY2019	cbsh	Common Stock Dividend Rate Percentage CommonStockDividendRatePercentage	0.05
CY2019Q4	cbsh	Tier One Risk Based Common Capital Requiredtobe Well Capitalizedto Risk Weighted Assets TierOneRiskBasedCommonCapitalRequiredtobeWellCapitalizedtoRiskWeightedAssets	0.065	Rate
CY2019Q4	us-gaap	Tier One Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets	0.080	Rate
CY2019Q4	us-gaap	Capital Required To Be Well Capitalized To Risk Weighted Assets CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets	0.100	Rate
CY2019Q4	us-gaap	Tier One Leverage Capital Required To Be Well Capitalized To Average Assets TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets	0.050	Rate
CY2019	cbsh	Percentof Revenuenotinscopeof Asc606 PercentofRevenuenotinscopeofASC606	0.61	Rate
CY2019	us-gaap	Noninterest Income NoninterestIncome	524703000	USD
CY2018	us-gaap	Noninterest Income NoninterestIncome	501341000	USD
CY2017	us-gaap	Noninterest Income NoninterestIncome	461263000	USD
CY2019	cbsh	Bank Card Transaction Fees BankCardTransactionFees	167879000	USD
CY2018	cbsh	Bank Card Transaction Fees BankCardTransactionFees	171576000	USD
CY2017	cbsh	Bank Card Transaction Fees BankCardTransactionFees	155100000	USD
CY2019	cbsh	Trustfeerevenue Trustfeerevenue	155628000	USD
CY2018	cbsh	Trustfeerevenue Trustfeerevenue	147964000	USD
CY2017	cbsh	Trustfeerevenue Trustfeerevenue	135159000	USD
CY2019Q4	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	26737000	USD
CY2018Q4	us-gaap	Mortgages Held For Sale Fair Value Disclosure MortgagesHeldForSaleFairValueDisclosure	13529000	USD
CY2018Q4	us-gaap	Financial Instruments Owned Us Government And Agency Obligations At Fair Value FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue	907652000	USD
CY2018Q4	cbsh	Us Government Sponsored Enterprises Debt Securities USGovernmentSponsoredEnterprisesDebtSecurities	195778000	USD
CY2018Q4	us-gaap	Financial Instruments Owned State And Municipal Government Obligations At Fair Value FinancialInstrumentsOwnedStateAndMunicipalGovernmentObligationsAtFairValue	1328039000	USD
CY2018Q4	cbsh	Financial Instruments Owned Agency Mortgage Backed Securities At Fair Value FinancialInstrumentsOwnedAgencyMortgageBackedSecuritiesAtFairValue	3214985000	USD
CY2019	cbsh	Depositfeerevenue Depositfeerevenue	95983000	USD
CY2018	cbsh	Depositfeerevenue Depositfeerevenue	94517000	USD
CY2017	cbsh	Depositfeerevenue Depositfeerevenue	90060000	USD
CY2019	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	15804000	USD
CY2018	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	15807000	USD
CY2017	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	14630000	USD
CY2019Q4	us-gaap	Mortgages Held For Sale Fair Value Disclosure MortgagesHeldForSaleFairValueDisclosure	9181000	USD
CY2019Q4	us-gaap	Financial Instruments Owned Us Government And Agency Obligations At Fair Value FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue	851776000	USD
CY2019Q4	cbsh	Us Government Sponsored Enterprises Debt Securities USGovernmentSponsoredEnterprisesDebtSecurities	139277000	USD
CY2019Q4	us-gaap	Financial Instruments Owned State And Municipal Government Obligations At Fair Value FinancialInstrumentsOwnedStateAndMunicipalGovernmentObligationsAtFairValue	1267927000	USD
CY2019Q4	cbsh	Financial Instruments Owned Agency Mortgage Backed Securities At Fair Value FinancialInstrumentsOwnedAgencyMortgageBackedSecuritiesAtFairValue	3937964000	USD
CY2019Q4	cbsh	Financial Instruments Owned Non Agency Mortgage Backed Securities At Fair Value FinancialInstrumentsOwnedNonAgencyMortgageBackedSecuritiesAtFairValue	809782000	USD
CY2019Q4	cbsh	Other Asset Backed Securities Disclosure OtherAssetBackedSecuritiesDisclosure	1233489000	USD
CY2019Q4	cbsh	Financial Instruments Owned Other Debt Securities At Fair Value FinancialInstrumentsOwnedOtherDebtSecuritiesAtFairValue	331411000	USD
CY2019Q4	us-gaap	Trading Securities TradingSecurities	28161000	USD
CY2019Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	2929000	USD
CY2019Q4	us-gaap	Financial Instruments Owned Principal Investments At Fair Value FinancialInstrumentsOwnedPrincipalInvestmentsAtFairValue	94122000	USD
CY2019Q4	us-gaap	Derivative Assets DerivativeAssets	105674000	USD
CY2019Q4	us-gaap	Deferred Compensation Plan Assets DeferredCompensationPlanAssets	16518000	USD
CY2019Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	8828211000	USD
CY2019Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	10219000	USD
CY2019Q4	us-gaap	Deferred Compensation Liability Current And Noncurrent DeferredCompensationLiabilityCurrentAndNoncurrent	16518000	USD
CY2018Q4	cbsh	Financial Instruments Owned Non Agency Mortgage Backed Securities At Fair Value FinancialInstrumentsOwnedNonAgencyMortgageBackedSecuritiesAtFairValue	1047716000	USD
CY2018Q4	cbsh	Other Asset Backed Securities Disclosure OtherAssetBackedSecuritiesDisclosure	1511614000	USD
CY2018Q4	cbsh	Financial Instruments Owned Other Debt Securities At Fair Value FinancialInstrumentsOwnedOtherDebtSecuritiesAtFairValue	332257000	USD
CY2018Q4	us-gaap	Trading Securities TradingSecurities	27059000	USD
CY2018Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	2585000	USD
CY2018Q4	us-gaap	Financial Instruments Owned Principal Investments At Fair Value FinancialInstrumentsOwnedPrincipalInvestmentsAtFairValue	85659000	USD
CY2018Q4	us-gaap	Derivative Assets DerivativeAssets	41210000	USD
CY2018Q4	us-gaap	Deferred Compensation Plan Assets DeferredCompensationPlanAssets	12968000	USD
CY2018Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	8721051000	USD
CY2018Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	13421000	USD
CY2018Q4	us-gaap	Deferred Compensation Liability Current And Noncurrent DeferredCompensationLiabilityCurrentAndNoncurrent	12968000	USD
CY2018Q4	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	26389000	USD
CY2018Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	100307000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	820000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Other Comprehensive Income Loss FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss	246000	USD
CY2019	cbsh	Investment Securities Called InvestmentSecuritiesCalled	4635000	USD
CY2019	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Discount Accretion FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetDiscountAccretion	84000	USD
CY2019	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchase Of Private Equity Securities FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchaseOfPrivateEquitySecurities	15706000	USD
CY2019	cbsh	Sales And Repayments Of Private Equity Securities SalesAndRepaymentsOfPrivateEquitySecurities	6548000	USD
CY2019	cbsh	Capitalized Interest Or Dividends CapitalizedInterestOrDividends	32000	USD
CY2019	cbsh	Purchase Of Risk Participation Agreement PurchaseOfRiskParticipationAgreement	439000	USD
CY2019	cbsh	Sale Of Risk Participation Agreement SaleOfRiskParticipationAgreement	467000	USD
CY2019Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	104344000	USD
CY2019	cbsh	Change In Unrealized Gains Or Losses Related To Assets Held Level3 Fair Value Measurements ChangeInUnrealizedGainsOrLossesRelatedToAssetsHeldLevel3FairValueMeasurements	-1720000	USD
CY2017Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	73271000	USD
CY2018	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	-13954000	USD
CY2018	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Other Comprehensive Income Loss FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss	-274000	USD
CY2018	cbsh	Investment Securities Called InvestmentSecuritiesCalled	2616000	USD
CY2018	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Discount Accretion FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetDiscountAccretion	32000	USD
CY2018	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchase Of Private Equity Securities FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchaseOfPrivateEquitySecurities	16395000	USD
CY2018	cbsh	Sales And Repayments Of Private Equity Securities SalesAndRepaymentsOfPrivateEquitySecurities	371000	USD
CY2018	cbsh	Capitalized Interest Or Dividends CapitalizedInterestOrDividends	34000	USD
CY2018	cbsh	Purchase Of Risk Participation Agreement PurchaseOfRiskParticipationAgreement	61000	USD
CY2018	cbsh	Sale Of Risk Participation Agreement SaleOfRiskParticipationAgreement	179000	USD
CY2018Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	100307000	USD
CY2018	cbsh	Change In Unrealized Gains Or Losses Related To Assets Held Level3 Fair Value Measurements ChangeInUnrealizedGainsOrLossesRelatedToAssetsHeldLevel3FairValueMeasurements	14512000	USD
CY2019	cbsh	Total Gains Or Losses Included In Earnings Level3 Fair Measurements TotalGainsOrLossesIncludedInEarningsLevel3FairMeasurements	-820000	USD
CY2019	cbsh	Change In Unrealized Gains Or Losses Related To Assets Held Level3 Fair Value Measurements ChangeInUnrealizedGainsOrLossesRelatedToAssetsHeldLevel3FairValueMeasurements	-1720000	USD
CY2018	cbsh	Total Gains Or Losses Included In Earnings Level3 Fair Measurements TotalGainsOrLossesIncludedInEarningsLevel3FairMeasurements	13954000	USD
CY2018	cbsh	Change In Unrealized Gains Or Losses Related To Assets Held Level3 Fair Value Measurements ChangeInUnrealizedGainsOrLossesRelatedToAssetsHeldLevel3FairValueMeasurements	14512000	USD
CY2019Q4	cbsh	Loans Nonrecurring Basis LoansNonrecurringBasis	422000	USD
CY2019	cbsh	Loans Nonrecurring Basis Gains Losses LoansNonrecurringBasisGainsLosses	-263000	USD
CY2019Q4	cbsh	Mortgage Servicing Rights Nonrecurring Basis MortgageServicingRightsNonrecurringBasis	7749000	USD
CY2019	cbsh	Mortgage Servicing Rights Nonrecurring Basis Gains Losses MortgageServicingRightsNonrecurringBasisGainsLosses	-327000	USD
CY2019Q4	cbsh	Long Lived Assets Nonrecurring Basis LongLivedAssetsNonrecurringBasis	1098000	USD
CY2019	cbsh	Long Lived Assets Nonrecurring Basis Gains Losses LongLivedAssetsNonrecurringBasisGainsLosses	-362000	USD
CY2018Q4	cbsh	Loans Nonrecurring Basis LoansNonrecurringBasis	294000	USD
CY2018	cbsh	Loans Nonrecurring Basis Gains Losses LoansNonrecurringBasisGainsLosses	-269000	USD
CY2018Q4	cbsh	Mortgage Servicing Rights Nonrecurring Basis MortgageServicingRightsNonrecurringBasis	6478000	USD
CY2018	cbsh	Mortgage Servicing Rights Nonrecurring Basis Gains Losses MortgageServicingRightsNonrecurringBasisGainsLosses	9000	USD
CY2018Q4	cbsh	Long Lived Assets Nonrecurring Basis LongLivedAssetsNonrecurringBasis	914000	USD
CY2018	cbsh	Long Lived Assets Nonrecurring Basis Gains Losses LongLivedAssetsNonrecurringBasisGainsLosses	-552000	USD
CY2019Q4	us-gaap	Derivative Notional Amount DerivativeNotionalAmount	4525856000	USD
CY2018Q4	us-gaap	Derivative Notional Amount DerivativeNotionalAmount	3254921000	USD
CY2019Q4	us-gaap	Derivative Assets DerivativeAssets	105674000	USD
CY2018Q4	us-gaap	Derivative Assets DerivativeAssets	41210000	USD
CY2019Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	10219000	USD
CY2018Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	13421000	USD
CY2019Q4	us-gaap	Derivative Asset Fair Value Gross Asset Including Not Subject To Master Netting Arrangement DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement	105674000	USD
CY2019Q4	cbsh	Derivative Asset Amount Offset By Liabiilty DerivativeAssetAmountOffsetByLiabiilty	0	USD
CY2019Q4	us-gaap	Derivative Assets DerivativeAssets	105674000	USD
CY2019Q4	us-gaap	Derivative Liability Fair Value Gross Liability Including Not Subject To Master Netting Arrangement DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement	10219000	USD
CY2019Q4	cbsh	Derivative Liability Amount Offset By Asset DerivativeLiabilityAmountOffsetByAsset	0	USD
CY2019Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	10219000	USD
CY2018Q4	us-gaap	Derivative Asset Fair Value Gross Asset Including Not Subject To Master Netting Arrangement DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement	41210000	USD
CY2018Q4	cbsh	Derivative Asset Amount Offset By Liabiilty DerivativeAssetAmountOffsetByLiabiilty	0	USD
CY2018Q4	us-gaap	Derivative Assets DerivativeAssets	41210000	USD
CY2018Q4	us-gaap	Derivative Liability Fair Value Gross Liability Including Not Subject To Master Netting Arrangement DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement	13421000	USD
CY2018Q4	cbsh	Derivative Liability Amount Offset By Asset DerivativeLiabilityAmountOffsetByAsset	0	USD
CY2018Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	13421000	USD
CY2019Q4	cbsh	Commercial Letters Of Credit CommercialLettersOfCredit	7050000	USD
CY2018Q4	cbsh	Commercial Letters Of Credit CommercialLettersOfCredit	13774000	USD
CY2019Q4	us-gaap	Purchase Commitment Remaining Minimum Amount Committed PurchaseCommitmentRemainingMinimumAmountCommitted	160900000	USD
CY2019	us-gaap	Related Party Transaction Expenses From Transactions With Related Party RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty	2733000	USD
CY2018	us-gaap	Related Party Transaction Expenses From Transactions With Related Party RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty	2480000	USD
CY2017	us-gaap	Related Party Transaction Expenses From Transactions With Related Party RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty	2446000	USD

Files In Submission

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$CBSH
COMMERCE BANCSHARES INC /MO/ Stock $cbsh

2020 Q1 Form 10-K Financial Statement

#000002235620000009 Filed on February 25, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CBSH COMMERCE BANCSHARES INC /MO/ Stock $cbsh

2020 Q1 Form 10-K Financial Statement

#000002235620000009 Filed on February 25, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CBSH
COMMERCE BANCSHARES INC /MO/ Stock $cbsh