$CBSH
COMMERCE BANCSHARES INC /MO/ Stock $cbsh

$cbsh Overview Financials Valuation SEC Filings Company Website

2020 Q4 Form 10-Q Financial Statement

#000002235620000055 Filed on November 05, 2020

Income Statement

Concept	2020 Q4	2020 Q3	2019 Q3
Revenue		$0.00	$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	$11.30M	$11.20M	$10.40M
YoY Change	8.65%	7.69%	8.33%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense		$7.152M	$28.23M
YoY Change		-74.67%	66.09%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$165.3M	$167.7M	$139.2M
YoY Change	21.99%	20.51%	-1.09%
Income Tax	$33.10M	$34.38M	$29.10M
% Of Pretax Income	20.02%	20.49%	20.91%
Net Earnings	$129.9M	$132.4M	$109.2M
YoY Change	21.52%	21.24%	-2.96%
Net Earnings / Revenue
Basic Earnings Per Share		$1.06	$0.93
Diluted Earnings Per Share	$1.062M	$1.06	$0.93
COMMON SHARES
Basic Shares Outstanding	111.5M shares	111.5M shares	109.7M shares
Diluted Shares Outstanding

Balance Sheet

Concept	2020 Q4	2020 Q3	2019 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$2.208B	$1.557B	$884.4M
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	$371.1M	$377.9M	$365.9M
YoY Change	0.12%	3.25%	10.27%
Goodwill	$138.9M	$138.9M	$138.9M
YoY Change	0.0%	0.0%	0.0%
Intangibles	$11.21M	$7.183M	$9.139M
YoY Change	17.55%	-21.4%	7.9%
Long-Term Investments	$18.00M
YoY Change
Other Assets
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$32.92B	$31.45B	$25.88B
YoY Change	26.31%	21.55%	3.25%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses			$27.00M
YoY Change
Deferred Revenue
YoY Change
Short-Term Debt	$2.098B	$1.653B	$1.641B
YoY Change	13.34%	0.73%	-11.87%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$2.098B	$1.653B	$27.00M
YoY Change	7670.37%	6022.22%	-98.55%
LONG-TERM LIABILITIES
Long-Term Debt	$1.000M	$1.000M	$257.0M
YoY Change	-50.0%	-99.61%	12750.0%
Other Long-Term Liabilities	$477.0M	$792.0M	$535.0M
YoY Change	-9.49%	48.04%	108.17%
Total Long-Term Liabilities	$478.0M	$793.0M	$792.0M
YoY Change	-9.64%	0.13%	205.79%
TOTAL LIABILITIES
Total Short-Term Liabilities	$2.098B	$1.653B	$27.00M
Total Long-Term Liabilities	$478.0M	$793.0M	$792.0M
Total Liabilities	$29.52B	$28.15B	$22.77B
YoY Change	28.77%	23.61%	2.32%
SHAREHOLDERS EQUITY
Retained Earnings	$73.00M	$326.9M	$463.2M
YoY Change	-63.78%	-29.43%	-6.16%
Common Stock	$589.4M	$564.0M	$559.4M
YoY Change	4.5%	0.81%	4.49%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$32.97M	$69.05M	$251.7M
YoY Change	-12.19%	-72.56%	658.62%
Treasury Stock Shares	497.4K shares	1.041M shares	4.315M shares
Shareholders Equity	$3.397B	$3.306B	$3.103B
YoY Change
Total Liabilities & Shareholders Equity	$32.92B	$31.45B	$25.88B
YoY Change	26.31%	21.55%	3.25%

Cashflow Statement

Concept	2020 Q4	2020 Q3	2019 Q3
OPERATING ACTIVITIES
Net Income	$129.9M	$132.4M	$109.2M
YoY Change	21.52%	21.24%	-2.96%
Depreciation, Depletion And Amortization	$11.30M	$11.20M	$10.40M
YoY Change	8.65%	7.69%	8.33%
Cash From Operating Activities	$151.6M	$242.7M	$125.6M
YoY Change	11.88%	93.23%	-20.81%
INVESTING ACTIVITIES
Capital Expenditures	-$3.900M	-$15.50M	-$9.100M
YoY Change	-70.45%	70.33%	15.19%
Acquisitions
YoY Change
Other Investing Activities	-$943.6M	-$1.488B	-$297.1M
YoY Change	259.06%	400.84%	-20.09%
Cash From Investing Activities	-$947.6M	-$1.503B	-$306.3M
YoY Change	243.46%	390.83%	-19.33%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	1.447B	1.000B	103.6M
YoY Change	783.27%	865.35%	-78.35%
NET CHANGE
Cash From Operating Activities	151.6M	242.7M	125.6M
Cash From Investing Activities	-947.6M	-1.503B	-306.3M
Cash From Financing Activities	1.447B	1.000B	103.6M
Net Change In Cash	650.8M	-260.6M	-77.10M
YoY Change	2681.2%	238.0%	-129.94%
FREE CASH FLOW
Cash From Operating Activities	$151.6M	$242.7M	$125.6M
Capital Expenditures	-$3.900M	-$15.50M	-$9.100M
Free Cash Flow	$155.5M	$258.2M	$134.7M
YoY Change	4.57%	91.69%	-19.1%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
	dei	Entity Central Index Key EntityCentralIndexKey	0000022356
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2020
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q3
	dei	Amendment Flag AmendmentFlag	false
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	8435531000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
	cbsh	Reclassification Where Impairment Was Not Previously Recognized ReclassificationWhereImpairmentWasNotPreviouslyRecognized	0	USD
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CY2020Q3	cbsh	Purchase Of Risk Participation Agreement PurchaseOfRiskParticipationAgreement	0	USD
	cbsh	Purchase Of Risk Participation Agreement PurchaseOfRiskParticipationAgreement	0	USD
CY2019Q3	cbsh	Capitalized Interest Or Dividends CapitalizedInterestOrDividends	0	USD
CY2019Q3	cbsh	Sales And Repayments Of Private Equity Securities SalesAndRepaymentsOfPrivateEquitySecurities	0	USD
CY2019Q3	cbsh	Gains Losses Included In Oci Attributable To Change In Unrealized Gains Losses Relating To Assets Still Held Total GainsLossesIncludedInOCIAttributableToChangeInUnrealizedGainsLossesRelatingToAssetsStillHeldTotal	0	USD
	cbsh	Gains Losses Included In Oci Attributable To Change In Unrealized Gains Losses Relating To Assets Still Held Total GainsLossesIncludedInOCIAttributableToChangeInUnrealizedGainsLossesRelatingToAssetsStillHeldTotal	0	USD
CY2020Q3	cbsh	Long Lived Assets Nonrecurring Basis LongLivedAssetsNonrecurringBasis	0	USD
	cbsh	Long Lived Assets Nonrecurring Basis Gains Losses LongLivedAssetsNonrecurringBasisGainsLosses	0	USD
	dei	Document Type DocumentType	10-Q
	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Document Period End Date DocumentPeriodEndDate	2020-09-30
	dei	Document Transition Report DocumentTransitionReport	false
	dei	Entity File Number EntityFileNumber	0-2989
	dei	Entity Registrant Name EntityRegistrantName	COMMERCE BANCSHARES, INC.
	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	MO
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	43-0889454
	dei	Entity Address Address Line1 EntityAddressAddressLine1	1000 Walnut,
	dei	Entity Address City Or Town EntityAddressCityOrTown	Kansas City,
	dei	Entity Address State Or Province EntityAddressStateOrProvince	MO
	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	64106
	dei	City Area Code CityAreaCode	816
	dei	Local Phone Number LocalPhoneNumber	234-2000
	dei	Security12b Title Security12bTitle	$5 Par Value Common Stock
	dei	Trading Symbol TradingSymbol	CBSH
	dei	Security Exchange Name SecurityExchangeName	NASDAQ
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
	dei	Entity Small Business EntitySmallBusiness	false
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Shell Company EntityShellCompany	false
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	us-gaap	Interest Expense Federal Funds Purchased And Securities Sold Under Agreements To Repurchase InterestExpenseFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchase	5761000	USD
	us-gaap	Interest Expense Federal Funds Purchased And Securities Sold Under Agreements To Repurchase InterestExpenseFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchase	23839000	USD
CY2020Q3	cbsh	Interest On Other Borrowings InterestOnOtherBorrowings	0	USD
CY2019Q3	cbsh	Interest On Other Borrowings InterestOnOtherBorrowings	453000	USD
	cbsh	Interest On Other Borrowings InterestOnOtherBorrowings	1032000	USD
	cbsh	Interest On Other Borrowings InterestOnOtherBorrowings	463000	USD
CY2020Q3	us-gaap	Interest Expense InterestExpense	7152000	USD
CY2019Q3	us-gaap	Interest Expense InterestExpense	28231000	USD
	us-gaap	Interest Expense InterestExpense	37838000	USD
	us-gaap	Interest Expense InterestExpense	79386000	USD
CY2020Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	215962000	USD
CY2019Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	203512000	USD
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	620084000	USD
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	618634000	USD
CY2020Q3	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	3101000	USD
CY2019Q3	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	10963000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	141593000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	35232000	USD
CY2020Q3	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	212861000	USD
CY2019Q3	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	192549000	USD
	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	478491000	USD
	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	583402000	USD
CY2020Q3	cbsh	Bank Card Transaction Fees BankCardTransactionFees	37873000	USD
CY2019Q3	cbsh	Bank Card Transaction Fees BankCardTransactionFees	44510000	USD
	cbsh	Bank Card Transaction Fees BankCardTransactionFees	111818000	USD
	cbsh	Bank Card Transaction Fees BankCardTransactionFees	126800000	USD
CY2020Q3	cbsh	Trustfeerevenue Trustfeerevenue	40769000	USD
CY2019Q3	cbsh	Trustfeerevenue Trustfeerevenue	39592000	USD
	cbsh	Trustfeerevenue Trustfeerevenue	118676000	USD
	cbsh	Trustfeerevenue Trustfeerevenue	115223000	USD
CY2020Q3	cbsh	Depositfeerevenue Depositfeerevenue	23107000	USD
CY2019Q3	cbsh	Depositfeerevenue Depositfeerevenue	24032000	USD
	cbsh	Depositfeerevenue Depositfeerevenue	69063000	USD
	cbsh	Depositfeerevenue Depositfeerevenue	71009000	USD
CY2020Q3	us-gaap	Noninterest Income Other NoninterestIncomeOther	3194000	USD
CY2019Q3	us-gaap	Noninterest Income Other NoninterestIncomeOther	1787000	USD
	us-gaap	Noninterest Income Other NoninterestIncomeOther	10756000	USD
	us-gaap	Noninterest Income Other NoninterestIncomeOther	5610000	USD
CY2020Q3	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	4011000	USD
CY2019Q3	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	4030000	USD
	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	11099000	USD
	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	11665000	USD
CY2020Q3	cbsh	Loan Fees And Sales LoanFeesAndSales	9769000	USD
CY2019Q3	cbsh	Loan Fees And Sales LoanFeesAndSales	4755000	USD
	cbsh	Loan Fees And Sales LoanFeesAndSales	17653000	USD
	cbsh	Loan Fees And Sales LoanFeesAndSales	12302000	USD
CY2020Q3	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	10849000	USD
CY2019Q3	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	14037000	USD
	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	31685000	USD
	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	38633000	USD
CY2020Q3	us-gaap	Noninterest Income NoninterestIncome	129572000	USD
CY2019Q3	us-gaap	Noninterest Income NoninterestIncome	132743000	USD
	us-gaap	Noninterest Income NoninterestIncome	370750000	USD
	us-gaap	Noninterest Income NoninterestIncome	381242000	USD
CY2020Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	16155000	USD
CY2019Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	4909000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	-1275000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	3874000	USD
CY2020Q3	us-gaap	Labor And Related Expense LaborAndRelatedExpense	127308000	USD
CY2019Q3	us-gaap	Labor And Related Expense LaborAndRelatedExpense	123836000	USD
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	383004000	USD
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	366026000	USD
CY2020Q3	us-gaap	Occupancy Net OccupancyNet	12058000	USD
CY2019Q3	us-gaap	Occupancy Net OccupancyNet	12293000	USD
	us-gaap	Occupancy Net OccupancyNet	35075000	USD
	us-gaap	Occupancy Net OccupancyNet	34939000	USD
CY2020Q3	us-gaap	Equipment Expense EquipmentExpense	4737000	USD
CY2019Q3	us-gaap	Equipment Expense EquipmentExpense	4941000	USD
	us-gaap	Equipment Expense EquipmentExpense	14313000	USD
	us-gaap	Equipment Expense EquipmentExpense	14202000	USD
CY2020Q3	cbsh	Supplies Postage And Communication SuppliesPostageAndCommunication	4141000	USD
CY2019Q3	cbsh	Supplies Postage And Communication SuppliesPostageAndCommunication	5106000	USD
	cbsh	Supplies Postage And Communication SuppliesPostageAndCommunication	15543000	USD
	cbsh	Supplies Postage And Communication SuppliesPostageAndCommunication	13226000	USD
CY2020Q3	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	23610000	USD
CY2019Q3	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	23457000	USD
	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	71002000	USD
	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	68965000	USD
CY2020Q3	us-gaap	Marketing Expense MarketingExpense	4926000	USD
CY2019Q3	us-gaap	Marketing Expense MarketingExpense	6048000	USD
	us-gaap	Marketing Expense MarketingExpense	14706000	USD
	us-gaap	Marketing Expense MarketingExpense	17963000	USD
CY2020Q3	us-gaap	Other Noninterest Expense OtherNoninterestExpense	14078000	USD
CY2019Q3	us-gaap	Other Noninterest Expense OtherNoninterestExpense	15339000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	40742000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	54586000	USD
CY2020Q3	us-gaap	Noninterest Expense NoninterestExpense	190858000	USD
CY2019Q3	us-gaap	Noninterest Expense NoninterestExpense	191020000	USD
	us-gaap	Noninterest Expense NoninterestExpense	572068000	USD
	us-gaap	Noninterest Expense NoninterestExpense	572224000	USD
CY2020Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	167730000	USD
CY2019Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	139181000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	275898000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	396294000	USD
CY2020Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	34375000	USD
CY2019Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	29101000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	54209000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	80860000	USD
CY2020Q3	us-gaap	Profit Loss ProfitLoss	133355000	USD
CY2019Q3	us-gaap	Profit Loss ProfitLoss	110080000	USD
	us-gaap	Profit Loss ProfitLoss	221689000	USD
	us-gaap	Profit Loss ProfitLoss	315434000	USD
CY2019Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	838000	USD
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	-2479000	USD
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	1083000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	132448000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	109242000	USD
	us-gaap	Net Income Loss NetIncomeLoss	224168000	USD
	us-gaap	Net Income Loss NetIncomeLoss	314351000	USD
CY2020Q3	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	7466000	USD
CY2019Q3	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	2250000	USD
	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	11966000	USD
	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	6750000	USD
CY2020Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	124982000	USD
CY2019Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	106992000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	212202000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	307601000	USD
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.12
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.93
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.90
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.65
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.11
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.93
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.89
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.65
CY2020Q3	us-gaap	Profit Loss ProfitLoss	133355000	USD
CY2019Q3	us-gaap	Profit Loss ProfitLoss	110080000	USD
	us-gaap	Profit Loss ProfitLoss	221689000	USD
	us-gaap	Profit Loss ProfitLoss	315434000	USD
CY2020Q3	cbsh	Net Unrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings NetUnrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings	0	USD
CY2019Q3	cbsh	Net Unrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings NetUnrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings	-245000	USD
	cbsh	Net Unrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings NetUnrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings	0	USD
	cbsh	Net Unrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings NetUnrealizedgainslossesonsecuritiesforwhichaportionofanotherthantemporaryimpairmenthasbeenrecordedinearnings	-432000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	330000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	21030000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	165464000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	171421000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-327000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-389000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1038000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1166000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	-6483000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	14101000	USD
	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	66489000	USD
	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	36687000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-5826000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	35275000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	232991000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	208842000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	127529000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	145355000	USD
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	454680000	USD
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	524276000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	907000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	838000	USD
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	-2479000	USD
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	1083000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	126622000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	144517000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	457159000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	523193000	USD
CY2020Q2	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3358169000	USD
CY2020Q3	us-gaap	Profit Loss ProfitLoss	133355000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-5826000	USD
CY2020Q3	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	608000	USD
CY2020Q3	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	167000	USD
CY2020Q3	us-gaap	Stock Redeemed Or Called During Period Value StockRedeemedOrCalledDuringPeriodValue	-150000000	USD
CY2020Q3	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	0	USD
CY2020Q3	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	3765000	USD
CY2020Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.270
CY2020Q3	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	30174000	USD
CY2020Q3	us-gaap	Preferred Stock Dividends Per Share Cash Paid PreferredStockDividendsPerShareCashPaid	0.375
CY2020Q3	us-gaap	Dividends Preferred Stock Cash DividendsPreferredStockCash	2250000	USD
CY2020Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3306264000	USD
CY2019Q2	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3171363000	USD
CY2019Q3	us-gaap	Profit Loss ProfitLoss	110080000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	35275000	USD
CY2019Q3	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	56000	USD
CY2019Q3	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	33891000	USD
CY2019Q3	us-gaap	Accelerated Share Repurchase Program Adjustment AcceleratedShareRepurchaseProgramAdjustment	-150000000	USD
CY2019Q3	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	0	USD
CY2019Q3	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	3486000	USD
CY2019Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.248
CY2019Q3	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	27993000	USD
CY2019Q3	us-gaap	Preferred Stock Dividends Per Share Cash Paid PreferredStockDividendsPerShareCashPaid	0.375
CY2019Q3	us-gaap	Dividends Preferred Stock Cash DividendsPreferredStockCash	2250000	USD
CY2019Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3106014000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3138472000	USD
	us-gaap	Profit Loss ProfitLoss	221689000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	232991000	USD
	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	708000	USD
	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	53760000	USD
	us-gaap	Stock Redeemed Or Called During Period Value StockRedeemedOrCalledDuringPeriodValue	-150000000	USD
	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	-27000	USD
	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	11231000	USD
	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.810
	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	90640000	USD
	us-gaap	Preferred Stock Dividends Per Share Cash Paid PreferredStockDividendsPerShareCashPaid	1.125
	us-gaap	Dividends Preferred Stock Cash DividendsPreferredStockCash	6750000	USD
CY2020Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3306264000	USD
CY2018Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2937149000	USD
	us-gaap	Profit Loss ProfitLoss	315434000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	208842000	USD
	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	3520000	USD
	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	119970000	USD
	us-gaap	Accelerated Share Repurchase Program Adjustment AcceleratedShareRepurchaseProgramAdjustment	-150000000	USD
	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	-3000	USD
	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	10365000	USD
	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.744
	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	85533000	USD
	us-gaap	Preferred Stock Dividends Per Share Cash Paid PreferredStockDividendsPerShareCashPaid	1.125
	us-gaap	Dividends Preferred Stock Cash DividendsPreferredStockCash	6750000	USD
CY2019Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3106014000	USD
	us-gaap	Profit Loss ProfitLoss	221689000	USD
	us-gaap	Profit Loss ProfitLoss	315434000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	141593000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	35232000	USD
	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	32462000	USD
	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	30729000	USD
	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-37623000	USD
	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-20436000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	-1275000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	3874000	USD
	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	8267000	USD
	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	7881000	USD
	cbsh	Origination Of Loans Held For Sale OriginationOfLoansHeldForSale	169774000	USD
	cbsh	Origination Of Loans Held For Sale OriginationOfLoansHeldForSale	187792000	USD
	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	152825000	USD
	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	194344000	USD
	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	-5636000	USD
	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	428000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	11231000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	10365000	USD
	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	11012000	USD
	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	-229000	USD
	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-7670000	USD
	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	5938000	USD
	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	-7942000	USD
	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	23530000	USD
	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-72714000	USD
	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	58928000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	472383000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	377334000	USD
	cbsh	Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities	574376000	USD
	cbsh	Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities	379641000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	1856780000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	1007553000	USD
	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	5135211000	USD
	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	1306607000	USD
	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	1710009000	USD
	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	357438000	USD
	us-gaap	Payments For Securities Purchased Under Agreements To Resell PaymentsForSecuritiesPurchasedUnderAgreementsToResell	0	USD
	us-gaap	Payments For Securities Purchased Under Agreements To Resell PaymentsForSecuritiesPurchasedUnderAgreementsToResell	150000000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	29192000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	29441000	USD
	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	313000	USD
	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	2029000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-4442943000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-454263000	USD
	cbsh	Net Increase Decrease Non Interest Bearing Savings Interest Checking And Money Market Deposits NetIncreaseDecreaseNonInterestBearingSavingsInterestCheckingAndMoneyMarketDeposits	5138314000	USD
	cbsh	Net Increase Decrease Non Interest Bearing Savings Interest Checking And Money Market Deposits NetIncreaseDecreaseNonInterestBearingSavingsInterestCheckingAndMoneyMarketDeposits	-230229000	USD
	us-gaap	Increase Decrease In Time Deposits IncreaseDecreaseInTimeDeposits	-17565000	USD
	us-gaap	Increase Decrease In Time Deposits IncreaseDecreaseInTimeDeposits	411098000	USD
	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	-197708000	USD
	us-gaap	Increase Decrease In Federal Funds Purchased And Securities Sold Under Agreements To Repurchase Net IncreaseDecreaseInFederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseNet	-315115000	USD
	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	0	USD
	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	163000	USD
	cbsh	Net Increase Decrease In Short Term Borrowings NetIncreaseDecreaseInShortTermBorrowings	-1636000	USD
	cbsh	Net Increase Decrease In Short Term Borrowings NetIncreaseDecreaseInShortTermBorrowings	248734000	USD
	us-gaap	Payments For Repurchase Of Redeemable Preferred Stock PaymentsForRepurchaseOfRedeemablePreferredStock	150000000	USD
	us-gaap	Payments For Repurchase Of Redeemable Preferred Stock PaymentsForRepurchaseOfRedeemablePreferredStock	0	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	53760000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	119970000	USD
	cbsh	Acceleratedstockrepurchaseagreement Acceleratedstockrepurchaseagreement	0	USD
	cbsh	Acceleratedstockrepurchaseagreement Acceleratedstockrepurchaseagreement	150000000	USD
	cbsh	Paymentsforstockvalueissuedundersharebasedcompensationplans Paymentsforstockvalueissuedundersharebasedcompensationplans	27000	USD
	cbsh	Paymentsforstockvalueissuedundersharebasedcompensationplans Paymentsforstockvalueissuedundersharebasedcompensationplans	3000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	90640000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	85533000	USD
	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	6750000	USD
	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	6750000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	4620228000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-247931000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	649668000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-324860000	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
CY2020Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	1557476000	USD
CY2019Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	884380000	USD
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	58750000	USD
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	54161000	USD
	us-gaap	Interest Paid Net InterestPaidNet	45508000	USD
	us-gaap	Interest Paid Net InterestPaidNet	73448000	USD
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	57000	USD
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	558000	USD
CY2020Q3	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	25900000	USD
CY2019Q3	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	25100000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	160682000	USD
CY2020Q1	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	139643000	USD
CY2019Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1075000	USD
CY2020Q1	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	17165000	USD
CY2019Q4	cbsh	Loans And Leases Receivable And Liability For Unfunded Lending Commitments Allowance LoansAndLeasesReceivableAndLiabilityForUnfundedLendingCommitmentsAllowance	161757000	USD
CY2020Q1	cbsh	Financing Receivable Allowance For Credit Losses And Liability For Unfunded Lending Commitments FinancingReceivableAllowanceForCreditLossesAndLiabilityForUnfundedLendingCommitments	156808000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	16420927000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	14737817000	USD
CY2020Q3	us-gaap	Interest Receivable InterestReceivable	41300000	USD
CY2020Q3	us-gaap	Pledged Financial Instruments Not Separately Reported Loans Receivable Pledged For Federal Home Loan Bank Debt PledgedFinancialInstrumentsNotSeparatelyReportedLoansReceivablePledgedForFederalHomeLoanBankDebt	4100000000	USD
CY2020Q3	cbsh	Pledged Financial Instruments Not Separately Reported Loans Pledged For Federal Reserve Bank Debt PledgedFinancialInstrumentsNotSeparatelyReportedLoansPledgedForFederalReserveBankDebt	1500000000	USD
CY2020Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	240744000	USD
CY2020Q1	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	139643000	USD
CY2020Q3	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	3200000	USD
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	123559000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	10649000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	36286000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	3065000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	9444000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	7584000	USD
	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	26842000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	236360000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	236360000	USD
CY2020Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	35299000	USD
CY2020Q1	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	17165000	USD
CY2020Q3	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-99000	USD
	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	18035000	USD
CY2020Q3	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	35200000	USD
CY2020Q3	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	35200000	USD
CY2020Q3	cbsh	Financing Receivable Allowance For Credit Loss And Unfunded Lending Commitments Total FinancingReceivableAllowanceForCreditLossAndUnfundedLendingCommitmentsTotal	271560000	USD
CY2020Q3	cbsh	Financing Receivable Allowance For Credit Loss And Unfunded Lending Commitments Total FinancingReceivableAllowanceForCreditLossAndUnfundedLendingCommitmentsTotal	271560000	USD
CY2019Q2	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	161182000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	159932000	USD
CY2019Q3	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	10963000	USD
	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	35232000	USD
CY2019Q3	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	14480000	USD
	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	43669000	USD
CY2019Q3	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	3017000	USD
	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	9187000	USD
CY2019Q3	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	11463000	USD
	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	34482000	USD
CY2019Q3	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	160682000	USD
CY2019Q3	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	160682000	USD
CY2020Q3	cbsh	Financing Receivable Recorded Investment Currentor Lessthan30days Past Due FinancingReceivableRecordedInvestmentCurrentorLessthan30daysPastDue	16296692000	USD
CY2020Q3	cbsh	Financing Receivable Recorded Investment Thirty To Eighty Nine Days Past Due FinancingReceivableRecordedInvestmentThirtyToEightyNineDaysPastDue	69529000	USD
CY2020Q3	us-gaap	Financing Receivable Recorded Investment90 Days Past Due And Still Accruing FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing	14436000	USD
CY2020Q3	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	40270000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	16420927000	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
CY2020Q3	cbsh	Credit Quality Personal Real Estate Loans Excluded CreditQualityPersonalRealEstateLoansExcluded	183300000	USD
CY2019Q4	cbsh	Credit Quality Personal Real Estate Loans Excluded CreditQualityPersonalRealEstateLoansExcluded	198200000	USD
CY2020Q3	cbsh	Consumer Healthcare Loans Excluded ConsumerHealthcareLoansExcluded	193200000	USD
CY2019Q4	cbsh	Consumer Healthcare Loans Excluded ConsumerHealthcareLoansExcluded	199200000	USD
CY2020Q3	cbsh	Credit Quality Personal Banking Loan Table Percentage Loans Excluded CreditQualityPersonalBankingLoanTablePercentageLoansExcluded	0.07	Rate
CY2020Q3	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	73161000	USD
CY2019Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	79450000	USD
	cbsh	Period After Which Loans Are Deemed In Default PeriodAfterWhichLoansAreDeemedInDefault	P90D
CY2020Q3	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	73161000	USD
CY2020Q3	cbsh	Financing Receivable Troubled Debt Restructurings That Subsequently Defaulted Recorded Investment FinancingReceivableTroubledDebtRestructuringsThatSubsequentlyDefaultedRecordedInvestment	1286000	USD
	cbsh	Effect On Interest Income Resulting From Modification To Credit Card Loans EffectOnInterestIncomeResultingFromModificationToCreditCardLoans	1100000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Impaired Commitment To Lend LoansAndLeasesReceivableImpairedCommitmentToLend	13100000	USD
CY2019Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	10220000	USD
CY2019Q4	cbsh	Accruing Restructured Loans AccruingRestructuredLoans	71512000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	81732000	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
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
CY2019Q3	cbsh	Financing Receivable Average Recorded Investment Nonaccrual Status FinancingReceivableAverageRecordedInvestmentNonaccrualStatus	11558000	USD
CY2019Q3	cbsh	Financing Receivable Modifications Average Recorded Investment FinancingReceivableModificationsAverageRecordedInvestment	69161000	USD
CY2019Q3	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	80719000	USD
	cbsh	Financing Receivable Average Recorded Investment Nonaccrual Status FinancingReceivableAverageRecordedInvestmentNonaccrualStatus	11955000	USD
	cbsh	Financing Receivable Modifications Average Recorded Investment FinancingReceivableModificationsAverageRecordedInvestment	63853000	USD
	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	75808000	USD
CY2019Q3	us-gaap	Impaired Financing Receivable Interest Income Accrual Method ImpairedFinancingReceivableInterestIncomeAccrualMethod	875000	USD
	us-gaap	Impaired Financing Receivable Interest Income Accrual Method ImpairedFinancingReceivableInterestIncomeAccrualMethod	2618000	USD
CY2020Q3	us-gaap	Mortgages Held For Sale Fair Value Disclosure MortgagesHeldForSaleFairValueDisclosure	35100000	USD
CY2020Q3	cbsh	Unpaid Principal Balanceon Personal Real Estate Loans Heldfor Sale UnpaidPrincipalBalanceonPersonalRealEstateLoansHeldforSale	33300000	USD
CY2020Q3	cbsh	Student Loans Heldfor Sale Lowerof Costor Fair Value StudentLoansHeldforSaleLowerofCostorFairValue	4400000	USD
CY2020Q3	cbsh	Hfs Loansonnonaccrualstatus HFSLoansonnonaccrualstatus	0	USD
CY2020Q3	cbsh	Loans Held For Sale90 Days Past Dueand Still Accruing LoansHeldForSale90DaysPastDueandStillAccruing	0	USD
CY2020Q3	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	57000	USD
CY2019Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	365000	USD
CY2020Q3	us-gaap	Other Foreclosed Assets OtherForeclosedAssets	1300000	USD
CY2019Q4	us-gaap	Other Foreclosed Assets OtherForeclosedAssets	5500000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	11539061000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	8571626000	USD
CY2020Q3	us-gaap	Trading Securities TradingSecurities	25805000	USD
CY2019Q4	us-gaap	Trading Securities TradingSecurities	28161000	USD
CY2020Q3	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	2803000	USD
CY2019Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	2929000	USD
CY2020Q3	cbsh	Equtiy Securitieswithout Readily Determinable Fair Values EqutiySecuritieswithoutReadilyDeterminableFairValues	1400000	USD
CY2019Q4	cbsh	Equtiy Securitieswithout Readily Determinable Fair Values EqutiySecuritieswithoutReadilyDeterminableFairValues	1280000	USD
CY2020Q3	us-gaap	Federal Reserve Bank Stock FederalReserveBankStock	34070000	USD
CY2019Q4	us-gaap	Federal Reserve Bank Stock FederalReserveBankStock	33770000	USD
CY2020Q3	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	10000000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	10000000	USD
CY2020Q3	cbsh	Private Equity Investments PrivateEquityInvestments	78462000	USD
CY2019Q4	cbsh	Private Equity Investments PrivateEquityInvestments	94122000	USD
CY2020Q3	cbsh	Total Investment Securities TotalInvestmentSecurities	11691601000	USD
CY2019Q4	cbsh	Total Investment Securities TotalInvestmentSecurities	8741888000	USD
CY2020Q3	us-gaap	Interest Receivable Current InterestReceivableCurrent	39700000	USD
CY2020Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	11182348000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	11539061000	USD
	cbsh	Percentage Decrease In Fair Value Below Amortized Cost PercentageDecreaseInFairValueBelowAmortizedCost	0.20
CY2020Q3	cbsh	Fair Value Securities On Impairment Watch List FairValueSecuritiesOnImpairmentWatchList	53300000	USD
CY2019Q4	cbsh	Fair Value Securities On Impairment Watch List FairValueSecuritiesOnImpairmentWatchList	51600000	USD
CY2020Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	596690000	USD
CY2020Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	8310000	USD
CY2020Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	246267000	USD
CY2020Q3	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	6241000	USD
CY2020Q3	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	842957000	USD
CY2020Q3	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	14551000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	1136297000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	9413000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	517817000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	3451000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	1654114000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	12864000	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	843000000.0	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	1700000000	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	14600000	USD
	cbsh	Af Ssecuritiesinlosspositionatperiodendchangeinunrealizedloss AFSsecuritiesinlosspositionatperiodendchangeinunrealizedloss	1700000	USD
CY2020Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	11182348000	USD
CY2020Q3	cbsh	Available For Sale Securities Gross Unreailzed Gainat Period End AvailableForSaleSecuritiesGrossUnreailzedGainatPeriodEnd	371264000	USD
CY2020Q3	cbsh	Available For Sale Securities Gross Unrealized Lossat Period End AvailableForSaleSecuritiesGrossUnrealizedLossatPeriodEnd	14551000	USD
CY2020Q3	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	11539061000	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
	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	574374000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	368939000	USD
	cbsh	Proceedsfromsaleofequitysecurities Proceedsfromsaleofequitysecurities	2000	USD
	cbsh	Proceedsfromsaleofequitysecurities Proceedsfromsaleofequitysecurities	3459000	USD
	cbsh	Proceeds From Sale Of Other Securities ProceedsFromSaleOfOtherSecurities	0	USD
	cbsh	Proceeds From Sale Of Other Securities ProceedsFromSaleOfOtherSecurities	7243000	USD
	cbsh	Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities	574376000	USD
	cbsh	Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities Proceedsfromsalesandmaturitiesofavailableforsaledebtequityandothersecurities	379641000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	-1275000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	3874000	USD
CY2020Q3	cbsh	Investment Securities Pledged At Fair Value InvestmentSecuritiesPledgedAtFairValue	4500000000	USD
CY2020Q3	us-gaap	Financial Instruments Owned And Pledged As Collateral Amount Eligible To Be Repledged By Counterparty FinancialInstrumentsOwnedAndPledgedAsCollateralAmountEligibleToBeRepledgedByCounterparty	218000000.0	USD
CY2020Q3	cbsh	Investments Exceeding Ten Percent Of Stockholders Equity InvestmentsExceedingTenPercentOfStockholdersEquity	0
CY2020Q3	cbsh	Percentage Of Stockholders Equity Of Which No Investment From Single Issuer Exceeds PercentageOfStockholdersEquityOfWhichNoInvestmentFromSingleIssuerExceeds	0.10
CY2020Q3	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	45253000	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	35920000	USD
CY2020Q3	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	2150000	USD
CY2020Q3	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	7183000	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
CY2020Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	859000	USD
CY2019Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	395000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1600000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1100000	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	2143000	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	1243000	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	1013000	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	834000	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	689000	USD
CY2020Q3	us-gaap	Goodwill Goodwill	138921000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	138921000	USD
CY2020Q3	us-gaap	Sales Type And Direct Financing Leases Profit Loss SalesTypeAndDirectFinancingLeasesProfitLoss	6437000	USD
CY2019Q3	us-gaap	Sales Type And Direct Financing Leases Profit Loss SalesTypeAndDirectFinancingLeasesProfitLoss	6092000	USD
	us-gaap	Sales Type And Direct Financing Leases Profit Loss SalesTypeAndDirectFinancingLeasesProfitLoss	19099000	USD
	us-gaap	Sales Type And Direct Financing Leases Profit Loss SalesTypeAndDirectFinancingLeasesProfitLoss	17988000	USD
CY2020Q3	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	2270000	USD
CY2019Q3	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	1984000	USD
	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	6491000	USD
	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	5816000	USD
CY2020Q3	us-gaap	Lease Income LeaseIncome	8707000	USD
CY2019Q3	us-gaap	Lease Income LeaseIncome	8076000	USD
	us-gaap	Lease Income LeaseIncome	25590000	USD
	us-gaap	Lease Income LeaseIncome	23804000	USD
CY2020Q3	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	93000	USD
CY2019Q3	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	159000	USD
	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	295000	USD
	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	477000	USD
CY2020Q3	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	818000	USD
CY2019Q3	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	1065000	USD
	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	2463000	USD
	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	3195000	USD
CY2020Q3	us-gaap	Defined Benefit Plan Expected Return On Plan Assets DefinedBenefitPlanExpectedReturnOnPlanAssets	1317000	USD
CY2019Q3	us-gaap	Defined Benefit Plan Expected Return On Plan Assets DefinedBenefitPlanExpectedReturnOnPlanAssets	1196000	USD
	us-gaap	Defined Benefit Plan Expected Return On Plan Assets DefinedBenefitPlanExpectedReturnOnPlanAssets	3911000	USD
	us-gaap	Defined Benefit Plan Expected Return On Plan Assets DefinedBenefitPlanExpectedReturnOnPlanAssets	3589000	USD
CY2020Q3	us-gaap	Defined Benefit Plan Amortization Of Prior Service Cost Credit DefinedBenefitPlanAmortizationOfPriorServiceCostCredit	-67000	USD
CY2019Q3	us-gaap	Defined Benefit Plan Amortization Of Prior Service Cost Credit DefinedBenefitPlanAmortizationOfPriorServiceCostCredit	-68000	USD
	us-gaap	Defined Benefit Plan Amortization Of Prior Service Cost Credit DefinedBenefitPlanAmortizationOfPriorServiceCostCredit	-203000	USD
	us-gaap	Defined Benefit Plan Amortization Of Prior Service Cost Credit DefinedBenefitPlanAmortizationOfPriorServiceCostCredit	-203000	USD
CY2020Q3	us-gaap	Defined Benefit Plan Amortization Of Gains Losses DefinedBenefitPlanAmortizationOfGainsLosses	-503000	USD
CY2019Q3	us-gaap	Defined Benefit Plan Amortization Of Gains Losses DefinedBenefitPlanAmortizationOfGainsLosses	-586000	USD
	us-gaap	Defined Benefit Plan Amortization Of Gains Losses DefinedBenefitPlanAmortizationOfGainsLosses	-1587000	USD
	us-gaap	Defined Benefit Plan Amortization Of Gains Losses DefinedBenefitPlanAmortizationOfGainsLosses	-1757000	USD
CY2020Q3	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	30000	USD
CY2019Q3	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	546000	USD
	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	231000	USD
	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	1637000	USD
	us-gaap	Defined Benefit Plan Contributions By Employer DefinedBenefitPlanContributionsByEmployer	0	USD
CY2020Q3	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	394000	shares
CY2019Q3	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	378000	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	281000	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	351000	shares
CY2020Q3	us-gaap	Preferred Stock Dividend Rate Percentage PreferredStockDividendRatePercentage	0.0600
CY2020Q3	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	1.00
CY2020Q3	us-gaap	Stock Redeemed Or Called During Period Shares StockRedeemedOrCalledDuringPeriodShares	6000000	shares
CY2020Q3	us-gaap	Preferred Stock Redemption Price Per Share PreferredStockRedemptionPricePerShare	25
	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	12000000.0	USD
	us-gaap	Preferred Stock Redemption Premium PreferredStockRedemptionPremium	5200000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	110444000	USD
	us-gaap	Other Comprehensive Income Loss Before Reclassifications Before Tax OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax	332285000	USD
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	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	310654000	USD
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	77663000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	232991000	USD
CY2020Q3	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	343435000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-64669000	USD
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	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Before Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax	-3710000	USD
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	278454000	USD
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	69612000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	208842000	USD
	cbsh	Reclassification Where Impairment Was Not Previously Recognized ReclassificationWhereImpairmentWasNotPreviouslyRecognized	0	USD
CY2019Q3	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	144173000	USD
	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	3	Operating_Segments
CY2020Q3	cbsh	Number Of Locations NumberOfLocations	160	Locations
CY2020Q3	us-gaap	Revenues Revenues	0	USD
CY2019Q3	us-gaap	Revenues Revenues	0	USD
	us-gaap	Revenues Revenues	0	USD
	us-gaap	Revenues Revenues	0	USD
CY2020Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	215962000	USD
CY2020Q3	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	3101000	USD
CY2020Q3	us-gaap	Noninterest Income NoninterestIncome	129572000	USD
CY2020Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	16155000	USD
CY2020Q3	us-gaap	Noninterest Expense NoninterestExpense	190858000	USD
CY2020Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	167730000	USD
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	620084000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	141593000	USD
	us-gaap	Noninterest Income NoninterestIncome	370750000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	-1275000	USD
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	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	275898000	USD
CY2019Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	203512000	USD
CY2019Q3	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	10963000	USD
CY2019Q3	us-gaap	Noninterest Income NoninterestIncome	132743000	USD
CY2019Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	4909000	USD
CY2019Q3	us-gaap	Noninterest Expense NoninterestExpense	191020000	USD
CY2019Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	139181000	USD
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	618634000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	35232000	USD
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	us-gaap	Gain Loss On Investments GainLossOnInvestments	3874000	USD
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	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	396294000	USD
CY2020Q3	us-gaap	Derivative Notional Amount DerivativeNotionalAmount	3548498000	USD
CY2019Q4	us-gaap	Derivative Notional Amount DerivativeNotionalAmount	4525856000	USD
CY2020Q3	us-gaap	Derivative Assets DerivativeAssets	147850000	USD
CY2019Q4	us-gaap	Derivative Assets DerivativeAssets	105674000	USD
CY2020Q3	us-gaap	Derivative Liabilities DerivativeLiabilities	20370000	USD
CY2019Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	10219000	USD
	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	33.97
CY2020Q3	us-gaap	Derivative Asset Fair Value Gross Asset Including Not Subject To Master Netting Arrangement DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement	147850000	USD
CY2020Q3	cbsh	Derivative Asset Amount Offset By Liabiilty DerivativeAssetAmountOffsetByLiabiilty	0	USD
CY2020Q3	us-gaap	Derivative Assets DerivativeAssets	147850000	USD
CY2020Q3	us-gaap	Derivative Liability Fair Value Gross Liability Including Not Subject To Master Netting Arrangement DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement	20370000	USD
CY2020Q3	cbsh	Derivative Liability Amount Offset By Asset DerivativeLiabilityAmountOffsetByAsset	0	USD
CY2020Q3	us-gaap	Derivative Liabilities DerivativeLiabilities	20370000	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
	cbsh	Nonvested Share Awards Forfeited In Period NonvestedShareAwardsForfeitedInPeriod	6730	shares
	cbsh	Share Based Compensation Forfeited Nonvested Share Award Weighted Average Grant Date Fair Value ShareBasedCompensationForfeitedNonvestedShareAwardWeightedAverageGrantDateFairValue	55.42
CY2020Q3	cbsh	Nonvested Share Awards Balances NonvestedShareAwardsBalances	1040668	shares
CY2020Q3	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	3800000	USD
CY2019Q3	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	3500000	USD
	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	11200000	USD
	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	10400000	USD
CY2019Q4	cbsh	Nonvested Share Awards Balances NonvestedShareAwardsBalances	1104211	shares
CY2019Q4	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
	cbsh	Nonvested Share Awards Granted In Period NonvestedShareAwardsGrantedInPeriod	218257	shares
	cbsh	Share Based Compensation Granted Nonvested Share Award Weighted Average Grant Date Fair Value ShareBasedCompensationGrantedNonvestedShareAwardWeightedAverageGrantDateFairValue	64.22
	cbsh	Nonvested Share Awards Vested In Period NonvestedShareAwardsVestedInPeriod	275070	shares
CY2020Q3	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Nonvested Share Awards Weighted Average Grant Date Unit Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsNonvestedShareAwardsWeightedAverageGrantDateUnitFairValue	54.61
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	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P5Y9M18D
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CY2019Q4	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePrice	43.55
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	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Expired In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpiredInPeriod	150	shares
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	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Exercised In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisedInPeriodWeightedAverageExercisePrice	34.52
CY2020Q3	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumber	997247	shares
CY2020Q3	cbsh	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePrice	46.86
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CY2020Q3	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Equity Instruments Other Than Options Aggregate Intrinsic Value Outstanding SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding	10582000	USD
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CY2020Q3	us-gaap	Noninterest Income NoninterestIncome	129572000	USD
CY2019Q3	us-gaap	Noninterest Income NoninterestIncome	132743000	USD
	us-gaap	Noninterest Income NoninterestIncome	370750000	USD
	us-gaap	Noninterest Income NoninterestIncome	381242000	USD
CY2020Q3	us-gaap	Mortgages Held For Sale Fair Value Disclosure MortgagesHeldForSaleFairValueDisclosure	35076000	USD
CY2020Q3	us-gaap	Financial Instruments Owned Us Government And Agency Obligations At Fair Value FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue	835058000	USD
CY2020Q3	cbsh	Us Government Sponsored Enterprises Debt Securities USGovernmentSponsoredEnterprisesDebtSecurities	95301000	USD
CY2020Q3	us-gaap	Financial Instruments Owned State And Municipal Government Obligations At Fair Value FinancialInstrumentsOwnedStateAndMunicipalGovernmentObligationsAtFairValue	1969144000	USD
CY2020Q3	cbsh	Financial Instruments Owned Agency Mortgage Backed Securities At Fair Value FinancialInstrumentsOwnedAgencyMortgageBackedSecuritiesAtFairValue	6081802000	USD
CY2020Q3	cbsh	Financial Instruments Owned Non Agency Mortgage Backed Securities At Fair Value FinancialInstrumentsOwnedNonAgencyMortgageBackedSecuritiesAtFairValue	332970000	USD
CY2020Q3	cbsh	Other Asset Backed Securities Disclosure OtherAssetBackedSecuritiesDisclosure	1658579000	USD
CY2020Q3	cbsh	Financial Instruments Owned Other Debt Securities At Fair Value FinancialInstrumentsOwnedOtherDebtSecuritiesAtFairValue	566207000	USD
CY2020Q3	us-gaap	Trading Securities TradingSecurities	25805000	USD
CY2020Q3	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	2803000	USD
CY2020Q3	us-gaap	Financial Instruments Owned Principal Investments At Fair Value FinancialInstrumentsOwnedPrincipalInvestmentsAtFairValue	78462000	USD
CY2020Q3	cbsh	Change In Unrealized Gains Or Losses Related To Assets Held Level3 Fair Value Measurements ChangeInUnrealizedGainsOrLossesRelatedToAssetsHeldLevel3FairValueMeasurements	5459000	USD
CY2020Q3	cbsh	Gains Losses Included In Oci Attributable To Change In Unrealized Gains Losses Relating To Assets Still Held Total GainsLossesIncludedInOCIAttributableToChangeInUnrealizedGainsLossesRelatingToAssetsStillHeldTotal	258000	USD
CY2020Q3	us-gaap	Derivative Assets DerivativeAssets	147850000	USD
CY2020Q3	us-gaap	Deferred Compensation Plan Assets DeferredCompensationPlanAssets	17294000	USD
CY2020Q3	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	11846351000	USD
CY2020Q3	us-gaap	Derivative Liabilities DerivativeLiabilities	20370000	USD
CY2020Q3	us-gaap	Deferred Compensation Liability Current And Noncurrent DeferredCompensationLiabilityCurrentAndNoncurrent	17294000	USD
CY2020Q3	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	37664000	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
CY2019Q4	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	26737000	USD
CY2020Q2	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	85224000	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	-2893000	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Other Comprehensive Income Loss FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss	271000	USD
CY2020Q3	cbsh	Investment Securities Called InvestmentSecuritiesCalled	-2000000	USD
CY2020Q3	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Discount Accretion FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetDiscountAccretion	105000	USD
CY2020Q3	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchase Of Private Equity Securities FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchaseOfPrivateEquitySecurities	2522000	USD
CY2020Q3	cbsh	Sales And Repayments Of Private Equity Securities SalesAndRepaymentsOfPrivateEquitySecurities	295000	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	88720000	USD
CY2019Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	104344000	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	15284000	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Other Comprehensive Income Loss FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss	-101000	USD
	cbsh	Investment Securities Called InvestmentSecuritiesCalled	-2000000	USD
	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Discount Accretion FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetDiscountAccretion	114000	USD
	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchase Of Private Equity Securities FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchaseOfPrivateEquitySecurities	2791000	USD
	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchase Of Private Equity Securities FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchaseOfPrivateEquitySecurities	2791000	USD
	cbsh	Sales And Repayments Of Private Equity Securities SalesAndRepaymentsOfPrivateEquitySecurities	364000	USD
	cbsh	Capitalized Interest Or Dividends CapitalizedInterestOrDividends	29000	USD
	cbsh	Sale Of Risk Participation Agreement SaleOfRiskParticipationAgreement	809000	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	88720000	USD
	cbsh	Change In Unrealized Gains Or Losses Related To Assets Held Level3 Fair Value Measurements ChangeInUnrealizedGainsOrLossesRelatedToAssetsHeldLevel3FairValueMeasurements	-14834000	USD
	cbsh	Gains Losses Included In Oci Attributable To Change In Unrealized Gains Losses Relating To Assets Still Held Total GainsLossesIncludedInOCIAttributableToChangeInUnrealizedGainsLossesRelatingToAssetsStillHeldTotal	-52000	USD
CY2019Q2	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	98935000	USD
CY2019Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	-1945000	USD
CY2019Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Other Comprehensive Income Loss FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss	-65000	USD
CY2019Q3	cbsh	Investment Securities Called InvestmentSecuritiesCalled	1715000	USD
CY2019Q3	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Discount Accretion FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetDiscountAccretion	36000	USD
CY2019Q3	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchase Of Private Equity Securities FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchaseOfPrivateEquitySecurities	5010000	USD
CY2019Q3	cbsh	Purchase Of Risk Participation Agreement PurchaseOfRiskParticipationAgreement	200000	USD
CY2019Q3	cbsh	Sale Of Risk Participation Agreement SaleOfRiskParticipationAgreement	241000	USD
CY2019Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	104105000	USD
CY2019Q3	cbsh	Change In Unrealized Gains Or Losses Related To Assets Held Level3 Fair Value Measurements ChangeInUnrealizedGainsOrLossesRelatedToAssetsHeldLevel3FairValueMeasurements	2880000	USD
CY2018Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	100307000	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	633000	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Other Comprehensive Income Loss FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss	294000	USD
	cbsh	Investment Securities Called InvestmentSecuritiesCalled	4635000	USD
	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Discount Accretion FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetDiscountAccretion	80000	USD
	cbsh	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchase Of Private Equity Securities FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchaseOfPrivateEquitySecurities	14899000	USD
	cbsh	Sales And Repayments Of Private Equity Securities SalesAndRepaymentsOfPrivateEquitySecurities	6150000	USD
	cbsh	Capitalized Interest Or Dividends CapitalizedInterestOrDividends	31000	USD
	cbsh	Purchase Of Risk Participation Agreement PurchaseOfRiskParticipationAgreement	226000	USD
	cbsh	Sale Of Risk Participation Agreement SaleOfRiskParticipationAgreement	314000	USD
CY2019Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	104105000	USD
	cbsh	Loans Nonrecurring Basis Gains Losses LoansNonrecurringBasisGainsLosses	-139000	USD
	cbsh	Change In Unrealized Gains Or Losses Related To Assets Held Level3 Fair Value Measurements ChangeInUnrealizedGainsOrLossesRelatedToAssetsHeldLevel3FairValueMeasurements	-1532000	USD
CY2020Q3	cbsh	Total Gains Or Losses Included In Earnings Level3 Fair Measurements TotalGainsOrLossesIncludedInEarningsLevel3FairMeasurements	2893000	USD
CY2020Q3	cbsh	Change In Unrealized Gains Or Losses Related To Assets Held Level3 Fair Value Measurements ChangeInUnrealizedGainsOrLossesRelatedToAssetsHeldLevel3FairValueMeasurements	5459000	USD
	cbsh	Total Gains Or Losses Included In Earnings Level3 Fair Measurements TotalGainsOrLossesIncludedInEarningsLevel3FairMeasurements	-15284000	USD
	cbsh	Change In Unrealized Gains Or Losses Related To Assets Held Level3 Fair Value Measurements ChangeInUnrealizedGainsOrLossesRelatedToAssetsHeldLevel3FairValueMeasurements	-14834000	USD
CY2019Q3	cbsh	Total Gains Or Losses Included In Earnings Level3 Fair Measurements TotalGainsOrLossesIncludedInEarningsLevel3FairMeasurements	1945000	USD
CY2019Q3	cbsh	Change In Unrealized Gains Or Losses Related To Assets Held Level3 Fair Value Measurements ChangeInUnrealizedGainsOrLossesRelatedToAssetsHeldLevel3FairValueMeasurements	2880000	USD
	cbsh	Total Gains Or Losses Included In Earnings Level3 Fair Measurements TotalGainsOrLossesIncludedInEarningsLevel3FairMeasurements	-633000	USD
	cbsh	Change In Unrealized Gains Or Losses Related To Assets Held Level3 Fair Value Measurements ChangeInUnrealizedGainsOrLossesRelatedToAssetsHeldLevel3FairValueMeasurements	-1532000	USD
CY2020Q3	cbsh	Loans Nonrecurring Basis LoansNonrecurringBasis	11772000	USD
	cbsh	Loans Nonrecurring Basis Gains Losses LoansNonrecurringBasisGainsLosses	-3214000	USD
CY2020Q3	cbsh	Mortgage Servicing Rights Nonrecurring Basis MortgageServicingRightsNonrecurringBasis	5731000	USD
	cbsh	Mortgage Servicing Rights Nonrecurring Basis Gains Losses MortgageServicingRightsNonrecurringBasisGainsLosses	-1823000	USD
CY2019Q3	cbsh	Loans Nonrecurring Basis LoansNonrecurringBasis	171000	USD
CY2019Q3	cbsh	Mortgage Servicing Rights Nonrecurring Basis MortgageServicingRightsNonrecurringBasis	7235000	USD
	cbsh	Mortgage Servicing Rights Nonrecurring Basis Gains Losses MortgageServicingRightsNonrecurringBasisGainsLosses	-404000	USD
CY2019Q3	cbsh	Long Lived Assets Nonrecurring Basis LongLivedAssetsNonrecurringBasis	820000	USD
	cbsh	Long Lived Assets Nonrecurring Basis Gains Losses LongLivedAssetsNonrecurringBasisGainsLosses	-318000	USD
	cbsh	Fair Value Discounted Cash Flow Valuation Techniques FairValueDiscountedCashFlowValuationTechniques	Discounted cash flow

Files In Submission

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$CBSH
COMMERCE BANCSHARES INC /MO/ Stock $cbsh

2020 Q4 Form 10-Q Financial Statement

#000002235620000055 Filed on November 05, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CBSH COMMERCE BANCSHARES INC /MO/ Stock $cbsh

2020 Q4 Form 10-Q Financial Statement

#000002235620000055 Filed on November 05, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CBSH
COMMERCE BANCSHARES INC /MO/ Stock $cbsh