$BKH
BLACK HILLS CORP /SD/ Stock $bkh

$bkh Overview Financials Valuation SEC Filings Company Website

2019 Q4 Form 10-K Financial Statement

#000113046420000006 Filed on February 14, 2020

Income Statement

Concept	2019 Q4	2018 Q4	2018 Q3
Revenue	$477.7M	$501.2M	$322.0M
YoY Change	-4.7%	10.08%	-4.06%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin	$400.0K
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$54.60M	$50.00M	$49.05M
YoY Change	9.2%	5.04%	4.11%
% of Gross Profit
Operating Expenses	$356.3M	$387.1M	$256.9M
YoY Change	-7.96%	14.49%	0.33%
Operating Profit	$121.4M	$114.1M	$65.09M
YoY Change	6.34%	-2.62%	-18.19%
Interest Expense	-$30.60M	-$141.0M	-$35.30M
YoY Change	-78.3%	307.51%	3.52%
% of Operating Profit	-25.21%	-123.55%	-54.24%
Other Income/Expense, Net	-$10.40M	$106.6M	-$35.81M
YoY Change	-109.76%	106500.0%	7.91%
Pretax Income	$80.40M	$79.70M	$29.28M
YoY Change	0.88%	-3.63%	-36.87%
Income Tax	$7.500M	-$11.90M	$7.500M
% Of Pretax Income	9.33%	-14.93%	25.62%
Net Earnings	$69.18M	$86.57M	$16.95M
YoY Change	-20.09%	70.75%	-46.36%
Net Earnings / Revenue	14.48%	17.27%	5.26%
Basic Earnings Per Share	$1.13	$1.50	$0.32
Diluted Earnings Per Share	$1.13	$1.49	$0.31
COMMON SHARES
Basic Shares Outstanding	61.45M shares	59.97M shares	53.36M shares
Diluted Shares Outstanding			54.82M shares

Balance Sheet

Concept	2019 Q4	2018 Q4	2018 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments	$9.800M	$20.80M	$10.00M
YoY Change	-52.88%	35.06%	-25.93%
Cash & Equivalents	$9.777M	$20.78M	$10.00M
Short-Term Investments
Other Short-Term Assets	$26.48M	$29.98M	$32.69M
YoY Change	-11.68%	18.19%	27.77%
Inventory	$117.2M	$117.3M	$122.6M
Prepaid Expenses
Receivables	$255.8M	$269.2M	$152.8M
Other Receivables	$16.40M	$13.00M	$11.10M
Total Short-Term Assets	$473.2M	$503.8M	$384.9M
YoY Change	-6.08%	-11.73%	-0.03%
LONG-TERM ASSETS
Property, Plant & Equipment	$5.503B	$4.855B	$4.700B
YoY Change	13.35%	6.9%	4.48%
Goodwill	$1.299B	$1.299B	$1.299B
YoY Change	0.0%	0.0%	0.0%
Intangibles	$13.27M	$14.34M	$6.954M
YoY Change	-7.47%	89.67%	-10.44%
Long-Term Investments	$21.90M	$41.00M	$41.20M
YoY Change	-46.59%	212.98%	219.38%
Other Assets	$41.31M	$14.35M	$17.14M
YoY Change	187.8%	41.41%	47.45%
Total Long-Term Assets	$7.085B	$6.459B	$6.277B
YoY Change	9.69%	6.1%	1.59%
TOTAL ASSETS
Total Short-Term Assets	$473.2M	$503.8M	$384.9M
Total Long-Term Assets	$7.085B	$6.459B	$6.277B
Total Assets	$7.558B	$6.963B	$6.662B
YoY Change	8.55%	4.57%	1.5%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$193.5M	$210.6M	$115.9M
YoY Change	-8.11%	30.9%	22.27%
Accrued Expenses	$226.8M	$215.5M	$201.4M
YoY Change	5.23%	-1.8%	-2.62%
Deferred Revenue
YoY Change
Short-Term Debt	$349.5M	$185.6M	$112.1M
YoY Change	88.29%	-12.15%	-50.22%
Long-Term Debt Due	$5.743M	$5.743M	$255.7M
YoY Change	0.0%	0.0%	4353.13%
Total Short-Term Liabilities	$811.3M	$648.2M	$730.2M
YoY Change	25.16%	-0.13%	31.75%
LONG-TERM LIABILITIES
Long-Term Debt	$3.140B	$2.951B	$2.951B
YoY Change	6.41%	-5.1%	-5.1%
Other Long-Term Liabilities	$124.7M	$109.4M	$105.9M
YoY Change	13.97%	3.44%	-7.08%
Total Long-Term Liabilities	$3.265B	$1.077B	$1.059B
YoY Change	203.18%	-0.31%	-4.03%
TOTAL LIABILITIES
Total Short-Term Liabilities	$811.3M	$648.2M	$730.2M
Total Long-Term Liabilities	$3.265B	$1.077B	$1.059B
Total Liabilities	$4.076B	$1.725B	$1.789B
YoY Change	136.28%	-0.24%	7.93%
SHAREHOLDERS EQUITY
Retained Earnings	$778.8M	$700.4M	$644.2M
YoY Change	11.19%	27.67%	24.75%
Common Stock	$61.48M	$60.05M	$53.66M
YoY Change	2.38%	12.07%	0.26%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$267.0K	$2.510M	$4.072M
YoY Change	-89.36%	8.85%	66.34%
Treasury Stock Shares	3.956K shares	44.25K shares	72.92K shares
Shareholders Equity	$2.362B	$2.182B	$1.813B
YoY Change
Total Liabilities & Shareholders Equity	$7.558B	$6.963B	$6.662B
YoY Change	8.55%	4.57%	1.5%

Cashflow Statement

Concept	2019 Q4	2018 Q4	2018 Q3
OPERATING ACTIVITIES
Net Income	$69.18M	$86.57M	$16.95M
YoY Change	-20.09%	70.75%	-46.36%
Depreciation, Depletion And Amortization	$54.60M	$50.00M	$49.05M
YoY Change	9.2%	5.04%	4.11%
Cash From Operating Activities	$119.4M	$110.1M	$68.00M
YoY Change	8.45%	1.1%	20.35%
INVESTING ACTIVITIES
Capital Expenditures	-$225.9M	-$179.4M	-$121.4M
YoY Change	25.92%	105.73%	43.67%
Acquisitions
YoY Change
Other Investing Activities	$2.900M	-$4.700M	$3.200M
YoY Change	-161.7%	-118.08%	-140.51%
Cash From Investing Activities	-$222.9M	-$184.0M	-$118.3M
YoY Change	21.14%	201.15%	27.89%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	100.4M	84.80M	51.80M
YoY Change	18.4%	-285.96%	36.32%
NET CHANGE
Cash From Operating Activities	119.4M	110.1M	68.00M
Cash From Investing Activities	-222.9M	-184.0M	-118.3M
Cash From Financing Activities	100.4M	84.80M	51.80M
Net Change In Cash	-3.100M	10.90M	1.500M
YoY Change	-128.44%	395.45%	-25.0%
FREE CASH FLOW
Cash From Operating Activities	$119.4M	$110.1M	$68.00M
Capital Expenditures	-$225.9M	-$179.4M	-$121.4M
Free Cash Flow	$345.3M	$289.5M	$189.4M
YoY Change	19.27%	47.63%	34.33%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2019Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	1
CY2018Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	100000000	shares
CY2019Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	100000000	shares
CY2019	dei	Entity Central Index Key EntityCentralIndexKey	0001130464
CY2018Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	1
CY2019	dei	Amendment Flag AmendmentFlag	false
CY2019	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2019	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2019	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2019
CY2018Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	60048567	shares
CY2019Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	61480658.32	shares
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	1100000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	1100000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	1100000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	1100000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	1299454000	USD
CY2017	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	-1030000	USD
CY2018	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	660000	USD
CY2019	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	-1886000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	-69000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	-43000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	-19000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Benefit Plan Improvement Tax Effect OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBenefitPlanImprovementTaxEffect	0	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Benefit Plan Improvement Tax Effect OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBenefitPlanImprovementTaxEffect	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Benefit Plan Improvement Tax Effect OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBenefitPlanImprovementTaxEffect	2000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax	585000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax	586000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax	-434000	USD
CY2018Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	44253	shares
CY2019Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	3956.1	shares
CY2018Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	0	USD
CY2017	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	0	USD
CY2018	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	0	USD
CY2019	dei	Document Type DocumentType	10-K
CY2019	dei	Document Annual Report DocumentAnnualReport	true
CY2019	dei	Document Period End Date DocumentPeriodEndDate	2019-12-31
CY2019	dei	Entity Address State Or Province EntityAddressStateOrProvince	SD
CY2019	dei	Document Transition Report DocumentTransitionReport	false
CY2019	dei	Entity File Number EntityFileNumber	001-31303
CY2019	dei	Entity Registrant Name EntityRegistrantName	BLACK HILLS CORPORATION
CY2019	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	SD
CY2019	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	46-0458824
CY2019	dei	Entity Address Address Line1 EntityAddressAddressLine1	7001 Mount Rushmore Road
CY2019	dei	Entity Address City Or Town EntityAddressCityOrTown	Rapid City
CY2019	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	57702
CY2019	dei	City Area Code CityAreaCode	(605)
CY2019	dei	Local Phone Number LocalPhoneNumber	721-1700
CY2019	dei	Security12b Title Security12bTitle	Common stock of $1.00 par value
CY2019	dei	Trading Symbol TradingSymbol	BKH
CY2019	dei	Security Exchange Name SecurityExchangeName	NYSE
CY2019	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2019	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2019	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2019	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2019	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2019	dei	Entity Small Business EntitySmallBusiness	false
CY2019	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2019	dei	Entity Shell Company EntityShellCompany	false
CY2019Q2	dei	Entity Public Float EntityPublicFloat	4727278183	USD
CY2020Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	61475403	shares
CY2019	us-gaap	Revenues Revenues	1734900000	USD
CY2018	us-gaap	Revenues Revenues	1754268000	USD
CY2017	us-gaap	Revenues Revenues	1680266000	USD
CY2019	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	570829000	USD
CY2018	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	625610000	USD
CY2017	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	563288000	USD
CY2019	bkh	Operating Expense Maintenance Operationsand Other Costsand Expense OperatingExpenseMaintenanceOperationsandOtherCostsandExpense	495994000	USD
CY2018	bkh	Operating Expense Maintenance Operationsand Other Costsand Expense OperatingExpenseMaintenanceOperationsandOtherCostsandExpense	481706000	USD
CY2017	bkh	Operating Expense Maintenance Operationsand Other Costsand Expense OperatingExpenseMaintenanceOperationsandOtherCostsandExpense	454605000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	209120000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	196328000	USD
CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	188246000	USD
CY2019	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	52915000	USD
CY2018	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	51746000	USD
CY2017	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	51578000	USD
CY2019	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	0	USD
CY2018	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	1841000	USD
CY2017	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	5813000	USD
CY2019	us-gaap	Operating Expenses OperatingExpenses	1328858000	USD
CY2018	us-gaap	Operating Expenses OperatingExpenses	1357231000	USD
CY2017	us-gaap	Operating Expenses OperatingExpenses	1263530000	USD
CY2019	us-gaap	Operating Income Loss OperatingIncomeLoss	406042000	USD
CY2018	us-gaap	Operating Income Loss OperatingIncomeLoss	397037000	USD
CY2017	us-gaap	Operating Income Loss OperatingIncomeLoss	416736000	USD
CY2019	us-gaap	Interest Costs Incurred InterestCostsIncurred	145847000	USD
CY2018	us-gaap	Interest Costs Incurred InterestCostsIncurred	143720000	USD
CY2017	us-gaap	Interest Costs Incurred InterestCostsIncurred	140533000	USD
CY2019	bkh	Public Utilities Allowance For Funds Used During Construction Borrowed Interest Costs Capitalized PublicUtilitiesAllowanceForFundsUsedDuringConstructionBorrowedInterestCostsCapitalized	6556000	USD
CY2018	bkh	Public Utilities Allowance For Funds Used During Construction Borrowed Interest Costs Capitalized PublicUtilitiesAllowanceForFundsUsedDuringConstructionBorrowedInterestCostsCapitalized	2104000	USD
CY2017	bkh	Public Utilities Allowance For Funds Used During Construction Borrowed Interest Costs Capitalized PublicUtilitiesAllowanceForFundsUsedDuringConstructionBorrowedInterestCostsCapitalized	2415000	USD
CY2019	us-gaap	Investment Income Interest InvestmentIncomeInterest	1632000	USD
CY2018	us-gaap	Investment Income Interest InvestmentIncomeInterest	1641000	USD
CY2017	us-gaap	Investment Income Interest InvestmentIncomeInterest	1016000	USD
CY2019	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	472000	USD
CY2018	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	619000	USD
CY2017	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	2321000	USD
CY2019	us-gaap	Other Asset Impairment Charges OtherAssetImpairmentCharges	19741000	USD
CY2018	us-gaap	Other Asset Impairment Charges OtherAssetImpairmentCharges	0	USD
CY2017	us-gaap	Other Asset Impairment Charges OtherAssetImpairmentCharges	0	USD
CY2019	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-6212000	USD
CY2018	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-1799000	USD
CY2017	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-213000	USD
CY2019	bkh	Total Other Income Expense TotalOtherIncomeExpense	-163140000	USD
CY2018	bkh	Total Other Income Expense TotalOtherIncomeExpense	-141155000	USD
CY2017	bkh	Total Other Income Expense TotalOtherIncomeExpense	-134994000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	242902000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	255882000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	281742000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	29580000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-23667000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	73367000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	213322000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	279549000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	208375000	USD
CY2019	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	USD
CY2018	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-6887000	USD
CY2017	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-17099000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	213322000	USD
CY2017	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	14242000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	272662000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	191276000	USD
CY2019	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	14012000	USD
CY2018	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	14220000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	199310000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	258442000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	177034000	USD
CY2019	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	199310000	USD
CY2018	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	265329000	USD
CY2017	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	194133000	USD
CY2019	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	USD
CY2018	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-6887000	USD
CY2017	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-17099000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	199310000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	258442000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	177034000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	3.29
CY2018	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	4.88
CY2017	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	3.65
CY2019	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	0
CY2018	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	-0.13
CY2017	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	-0.32
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.29
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	4.75
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.33
CY2019	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	3.28
CY2018	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	4.78
CY2017	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	3.52
CY2019	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0
CY2018	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.12
CY2017	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.31
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.28
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	4.66
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.21
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	60662000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	54420000	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	53221000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	60798000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	55486000	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	55120000	shares
CY2018	us-gaap	Profit Loss ProfitLoss	272662000	USD
CY2018	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	2155000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	213322000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	191276000	USD
CY2019	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	-6253000	USD
CY2017	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	-1890000	USD
CY2019	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Costs Credit Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostsCreditArisingDuringPeriodNetOfTax	8000	USD
CY2018	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Costs Credit Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostsCreditArisingDuringPeriodNetOfTax	0	USD
CY2017	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Costs Credit Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostsCreditArisingDuringPeriodNetOfTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-1179000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-1901000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-1072000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	-58000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	-135000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	-128000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-3739000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	7027000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	681000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	209583000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	279689000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	191957000	USD
CY2019	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	14012000	USD
CY2018	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	14220000	USD
CY2017	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	14242000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	195571000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	265469000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	177715000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	9777000	USD
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	20776000	USD
CY2019Q4	us-gaap	Restricted Cash And Investments Current RestrictedCashAndInvestmentsCurrent	3881000	USD
CY2018Q4	us-gaap	Restricted Cash And Investments Current RestrictedCashAndInvestmentsCurrent	3369000	USD
CY2019Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	255805000	USD
CY2018Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	269153000	USD
CY2019Q4	us-gaap	Inventory Net InventoryNet	117172000	USD
CY2018Q4	us-gaap	Inventory Net InventoryNet	117299000	USD
CY2019Q4	us-gaap	Derivative Assets Current DerivativeAssetsCurrent	342000	USD
CY2018Q4	us-gaap	Derivative Assets Current DerivativeAssetsCurrent	1500000	USD
CY2019Q4	us-gaap	Income Taxes Receivable IncomeTaxesReceivable	16446000	USD
CY2018Q4	us-gaap	Income Taxes Receivable IncomeTaxesReceivable	12978000	USD
CY2019Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	43282000	USD
CY2018Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	48776000	USD
CY2019Q4	us-gaap	Other Assets Current OtherAssetsCurrent	26479000	USD
CY2018Q4	us-gaap	Other Assets Current OtherAssetsCurrent	29982000	USD
CY2019Q4	us-gaap	Assets Current AssetsCurrent	473184000	USD
CY2018Q4	us-gaap	Assets Current AssetsCurrent	503833000	USD
CY2019Q4	us-gaap	Long Term Investments LongTermInvestments	21929000	USD
CY2018Q4	us-gaap	Long Term Investments LongTermInvestments	41013000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	6784679000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	6000015000	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1281493000	USD
CY2018Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1145136000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	5503186000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	4854879000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	1299454000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	1299454000	USD
CY2019Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	13266000	USD
CY2018Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	14337000	USD
CY2019Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	228062000	USD
CY2018Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	235459000	USD
CY2019Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	19376000	USD
CY2018Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	14352000	USD
CY2019Q4	us-gaap	Assets Noncurrent Other Than Noncurrent Investments And Property Plant And Equipment AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment	1560158000	USD
CY2018Q4	us-gaap	Assets Noncurrent Other Than Noncurrent Investments And Property Plant And Equipment AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment	1563602000	USD
CY2019Q4	us-gaap	Assets Assets	7558457000	USD
CY2018Q4	us-gaap	Assets Assets	6963327000	USD
CY2019Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	193523000	USD
CY2018Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	210609000	USD
CY2019Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	226767000	USD
CY2018Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	215501000	USD
CY2019Q4	us-gaap	Derivative Liabilities Current DerivativeLiabilitiesCurrent	2254000	USD
CY2018Q4	us-gaap	Derivative Liabilities Current DerivativeLiabilitiesCurrent	947000	USD
CY2019Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	33507000	USD
CY2018Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	29810000	USD
CY2019Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	349500000	USD
CY2018Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	185620000	USD
CY2019Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	5743000	USD
CY2018Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	5743000	USD
CY2019Q4	us-gaap	Liabilities Current LiabilitiesCurrent	811294000	USD
CY2018Q4	us-gaap	Liabilities Current LiabilitiesCurrent	648230000	USD
CY2019Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	3140096000	USD
CY2018Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	2950835000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	360719000	USD
CY2018Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	311331000	USD
CY2019Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	154472000	USD
CY2019Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	503145000	USD
CY2018Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	510984000	USD
CY2018Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	145147000	USD
CY2019Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	124662000	USD
CY2018Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	109377000	USD
CY2019Q4	us-gaap	Liabilities Other Than Longterm Debt Noncurrent LiabilitiesOtherThanLongtermDebtNoncurrent	1142998000	USD
CY2018Q4	us-gaap	Liabilities Other Than Longterm Debt Noncurrent LiabilitiesOtherThanLongtermDebtNoncurrent	1076839000	USD
CY2019Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2018Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2019Q4	us-gaap	Common Stock Value CommonStockValue	61481000	USD
CY2018Q4	us-gaap	Common Stock Value CommonStockValue	60049000	USD
CY2019Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	1552788000	USD
CY2018Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	1450569000	USD
CY2019Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	778776000	USD
CY2018Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	700396000	USD
CY2019Q4	us-gaap	Treasury Stock Value TreasuryStockValue	267000	USD
CY2018Q4	us-gaap	Treasury Stock Value TreasuryStockValue	2510000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-30655000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-26916000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	2362123000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	2181588000	USD
CY2019Q4	us-gaap	Noncontrolling Interest In Variable Interest Entity NoncontrollingInterestInVariableInterestEntity	101946000	USD
CY2018Q4	us-gaap	Noncontrolling Interest In Variable Interest Entity NoncontrollingInterestInVariableInterestEntity	105835000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2464069000	USD
CY2018Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2287423000	USD
CY2019Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	7558457000	USD
CY2018Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	6963327000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	213322000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	272662000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	191276000	USD
CY2019	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	USD
CY2018	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-6887000	USD
CY2017	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-17099000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	213322000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	279549000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	208375000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	209120000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	196328000	USD
CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	188246000	USD
CY2019	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	7838000	USD
CY2018	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	7845000	USD
CY2017	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	8261000	USD
CY2019	us-gaap	Other Asset Impairment Charges OtherAssetImpairmentCharges	19741000	USD
CY2018	us-gaap	Other Asset Impairment Charges OtherAssetImpairmentCharges	0	USD
CY2017	us-gaap	Other Asset Impairment Charges OtherAssetImpairmentCharges	0	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	12095000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	12390000	USD
CY2017	us-gaap	Share Based Compensation ShareBasedCompensation	7626000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	38020000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-24239000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	80992000	USD
CY2019	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	12406000	USD
CY2018	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	14068000	USD
CY2017	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	10141000	USD
CY2019	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-16485000	USD
CY2018	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-5836000	USD
CY2017	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	4773000	USD
CY2019	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-2052000	USD
CY2018	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	2919000	USD
CY2017	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	10089000	USD
CY2019	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	-7578000	USD
CY2018	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	45966000	USD
CY2017	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	-4534000	USD
CY2019	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	-34906000	USD
CY2018	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	5305000	USD
CY2017	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	-28222000	USD
CY2019	us-gaap	Increase Decrease In Other Regulatory Assets IncreaseDecreaseInOtherRegulatoryAssets	-23619000	USD
CY2018	us-gaap	Increase Decrease In Other Regulatory Assets IncreaseDecreaseInOtherRegulatoryAssets	-33608000	USD
CY2017	us-gaap	Increase Decrease In Other Regulatory Assets IncreaseDecreaseInOtherRegulatoryAssets	15407000	USD
CY2019	us-gaap	Increase Decrease In Regulatory Liabilities IncreaseDecreaseInRegulatoryLiabilities	-15158000	USD
CY2018	us-gaap	Increase Decrease In Regulatory Liabilities IncreaseDecreaseInRegulatoryLiabilities	18533000	USD
CY2017	us-gaap	Increase Decrease In Regulatory Liabilities IncreaseDecreaseInRegulatoryLiabilities	-4536000	USD
CY2019	us-gaap	Pension Contributions PensionContributions	12700000	USD
CY2018	us-gaap	Pension Contributions PensionContributions	12700000	USD
CY2017	us-gaap	Pension Contributions PensionContributions	27700000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-6001000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-6689000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	8418000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	505513000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	494327000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	409030000	USD
CY2019	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	0	USD
CY2018	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	-5516000	USD
CY2017	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	19231000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	505513000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	488811000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	428261000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	818376000	USD
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	457524000	USD
CY2017	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	326010000	USD
CY2019	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	0	USD
CY2018	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	24429000	USD
CY2017	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	0	USD
CY2019	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-2166000	USD
CY2018	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	4281000	USD
CY2017	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-1011000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-816210000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-486234000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-324999000	USD
CY2019	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	0	USD
CY2018	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	20385000	USD
CY2017	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	7881000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-816210000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-465849000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-317118000	USD
CY2019	us-gaap	Payments Of Dividends PaymentsOfDividends	124647000	USD
CY2018	us-gaap	Payments Of Dividends PaymentsOfDividends	106591000	USD
CY2017	us-gaap	Payments Of Dividends PaymentsOfDividends	96744000	USD
CY2019	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	101358000	USD
CY2018	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	300834000	USD
CY2017	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	4408000	USD
CY2019	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	163880000	USD
CY2018	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-25680000	USD
CY2017	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	114700000	USD
CY2019	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	1100000000	USD
CY2018	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	700000000	USD
CY2017	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	0	USD
CY2019	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	905743000	USD
CY2018	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	854743000	USD
CY2017	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	105743000	USD
CY2019	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	17901000	USD
CY2018	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	19617000	USD
CY2017	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	18397000	USD
CY2019	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-16737000	USD
CY2018	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-11260000	USD
CY2017	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-6919000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	300210000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-17057000	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-108695000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-10487000	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	5905000	USD
CY2017	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	2448000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	24145000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	18240000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	15792000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	13658000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	24145000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	18240000	USD
CY2016Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1730134000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	191276000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	681000	USD
CY2017	bkh	Tax Cutsand Jobs Actof2017 Reclassificationfrom Aoc Ito Retained Earnings TaxCutsandJobsActof2017ReclassificationfromAOCItoRetainedEarnings	0	USD
CY2017	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	96744000	USD
CY2017	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	7567000	USD
CY2017	us-gaap	Adjustment To Additional Paid In Capital Income Tax Effect From Share Based Compensation Net AdjustmentToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet	3717000	USD
CY2017	us-gaap	Adjustments To Additional Paid In Capital Stock Issued Issuance Costs AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts	189000	USD
CY2017	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	3156000	USD
CY2017	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	19392000	USD
CY2017Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1820206000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	272662000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	7027000	USD
CY2018	bkh	Tax Cutsand Jobs Actof2017 Reclassificationfrom Aoc Ito Retained Earnings TaxCutsandJobsActof2017ReclassificationfromAOCItoRetainedEarnings	740000	USD
CY2018	bkh	Reclassificationfrom Legal Entity Restructuring ReclassificationfromLegalEntityRestructuring	6519000	USD
CY2018	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	106591000	USD
CY2018	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	7190000	USD
CY2018	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	299000000	USD
CY2018	us-gaap	Adjustments To Additional Paid In Capital Stock Issued Issuance Costs AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts	15000	USD
CY2018	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	220000	USD
CY2018	us-gaap	Stockholders Equity Other StockholdersEquityOther	-82000	USD
CY2018	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	19617000	USD
CY2018Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2287423000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	213322000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-3739000	USD
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	124647000	USD
CY2019	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	7076000	USD
CY2019	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	100000000	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Stock Issued Issuance Costs AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts	1182000	USD
CY2019	us-gaap	Stockholders Equity Other StockholdersEquityOther	-327000	USD
CY2019Q4	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	3390000	USD
CY2019	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	17901000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2464069000	USD
CY2019	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	2.05
CY2018	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.93
CY2017	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.81
CY2019	us-gaap	Use Of Estimates UseOfEstimates	<div style="line-height:120%;text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-weight:bold;">Use of Estimates and Basis of Presentation</span></div><div style="line-height:120%;text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div><div style="line-height:120%;text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of certain assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Changes in facts and circumstances or additional information may result in revised estimates and actual results could differ materially from those estimates.</span></div>
CY2019Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	2444000	USD
CY2019Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	255805000	USD
CY2018Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	3209000	USD
CY2018Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	269153000	USD
CY2018Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	3209000	USD
CY2019	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	5795000	USD
CY2019	us-gaap	Valuation Allowances And Reserves Recoveries ValuationAllowancesAndReservesRecoveries	3942000	USD
CY2019	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	10502000	USD
CY2019Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	2444000	USD
CY2017Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	3081000	USD
CY2018	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	6859000	USD
CY2018	us-gaap	Valuation Allowances And Reserves Recoveries ValuationAllowancesAndReservesRecoveries	4092000	USD
CY2018	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	10823000	USD
CY2018Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	3209000	USD
CY2016Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	2392000	USD
CY2017	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	4926000	USD
CY2017	us-gaap	Valuation Allowances And Reserves Recoveries ValuationAllowancesAndReservesRecoveries	8262000	USD
CY2017	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	12499000	USD
CY2017Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	3081000	USD
CY2019Q4	us-gaap	Inventory Raw Materials And Supplies InventoryRawMaterialsAndSupplies	82809000	USD
CY2018Q4	us-gaap	Inventory Raw Materials And Supplies InventoryRawMaterialsAndSupplies	75081000	USD
CY2019Q4	us-gaap	Energy Related Inventory Other Fossil Fuel EnergyRelatedInventoryOtherFossilFuel	2425000	USD
CY2018Q4	us-gaap	Energy Related Inventory Other Fossil Fuel EnergyRelatedInventoryOtherFossilFuel	2850000	USD
CY2019Q4	us-gaap	Energy Related Inventory Natural Gas In Storage EnergyRelatedInventoryNaturalGasInStorage	31938000	USD
CY2018Q4	us-gaap	Energy Related Inventory Natural Gas In Storage EnergyRelatedInventoryNaturalGasInStorage	39368000	USD
CY2019Q4	us-gaap	Inventory Net InventoryNet	117172000	USD
CY2018Q4	us-gaap	Inventory Net InventoryNet	117299000	USD
CY2019Q1	bkh	Assets Usedto Acquire Other Investments AssetsUsedtoAcquireOtherInvestments	28000000	USD
CY2019Q4	bkh	Discount Rate Usedin Valuationof Fair Valueof Oiland Gas Reserve Quantities DiscountRateUsedinValuationofFairValueofOilandGasReserveQuantities	0.10
CY2019	us-gaap	Other Asset Impairment Charges OtherAssetImpairmentCharges	20000000	USD
CY2019Q4	us-gaap	Long Term Investments LongTermInvestments	21929000	USD
CY2018Q4	us-gaap	Long Term Investments LongTermInvestments	41013000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	1299454000	USD
CY2018Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	14337000	USD
CY2017Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	7559000	USD
CY2016Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	8392000	USD
CY2019	bkh	Finite Lived Intangible Asset Purchase Accounting Adjustments FiniteLivedIntangibleAssetPurchaseAccountingAdjustments	0	USD
CY2018	bkh	Finite Lived Intangible Asset Purchase Accounting Adjustments FiniteLivedIntangibleAssetPurchaseAccountingAdjustments	7602000	USD
CY2017	bkh	Finite Lived Intangible Asset Purchase Accounting Adjustments FiniteLivedIntangibleAssetPurchaseAccountingAdjustments	0	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1071000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	824000	USD
CY2017	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	833000	USD
CY2019Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	13266000	USD
CY2018Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	14337000	USD
CY2017Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	7559000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	1100000	USD
CY2019Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	62837000	USD
CY2018Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	63742000	USD
CY2019Q4	us-gaap	Accrual For Taxes Other Than Income Taxes Current AccrualForTaxesOtherThanIncomeTaxesCurrent	44547000	USD
CY2018Q4	us-gaap	Accrual For Taxes Other Than Income Taxes Current AccrualForTaxesOtherThanIncomeTaxesCurrent	42510000	USD
CY2019Q4	bkh	Customer Depositsand Prepayments CustomerDepositsandPrepayments	54728000	USD
CY2018Q4	bkh	Customer Depositsand Prepayments CustomerDepositsandPrepayments	43574000	USD
CY2019Q4	us-gaap	Interest Payable Current InterestPayableCurrent	31868000	USD
CY2018Q4	us-gaap	Interest Payable Current InterestPayableCurrent	31759000	USD
CY2019Q4	us-gaap	Contributions In Aid Of Construction ContributionsInAidOfConstruction	1952000	USD
CY2018Q4	us-gaap	Contributions In Aid Of Construction ContributionsInAidOfConstruction	1485000	USD
CY2019Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	30835000	USD
CY2018Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	32431000	USD
CY2019Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	226767000	USD
CY2018Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	215501000	USD
CY2019Q4	us-gaap	Regulatory Assets RegulatoryAssets	271000000	USD
CY2018Q4	us-gaap	Regulatory Assets RegulatoryAssets	284000000	USD
CY2019Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	537000000	USD
CY2018Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	541000000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	199310000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	258442000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	177034000	USD
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	60662000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	54420000	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	53221000	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Equity Unit Purchase Agreements IncrementalCommonSharesAttributableToEquityUnitPurchaseAgreements	0	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Equity Unit Purchase Agreements IncrementalCommonSharesAttributableToEquityUnitPurchaseAgreements	898000	shares
CY2017	us-gaap	Incremental Common Shares Attributable To Equity Unit Purchase Agreements IncrementalCommonSharesAttributableToEquityUnitPurchaseAgreements	1783000	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	136000	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	168000	shares
CY2017	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	116000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	60798000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	55486000	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	55120000	shares
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.28
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	4.66
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.21
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1000	shares
CY2018	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	16000	shares
CY2017	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	11000	shares
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1726392000	USD
CY2019	us-gaap	Revenues Revenues	1734900000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1726392000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1748542000	USD
CY2018	us-gaap	Revenues Revenues	1754268000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1748542000	USD
CY2018Q4	us-gaap	Business Combination Consideration Transferred1 BusinessCombinationConsiderationTransferred1	16000000	USD
CY2019Q4	us-gaap	Assets Assets	7558457000	USD
CY2018Q4	us-gaap	Assets Assets	6963327000	USD
CY2019	us-gaap	Property Plant And Equipment Gross Period Increase Decrease PropertyPlantAndEquipmentGrossPeriodIncreaseDecrease	849755000	USD
CY2018	us-gaap	Property Plant And Equipment Gross Period Increase Decrease PropertyPlantAndEquipmentGrossPeriodIncreaseDecrease	504826000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	6784679000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	6000015000	USD
CY2019	us-gaap	Revenues Revenues	1734900000	USD
CY2019	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	570829000	USD
CY2019	us-gaap	Costs And Expenses CostsAndExpenses	548909000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	209120000	USD
CY2019	us-gaap	Operating Income Loss OperatingIncomeLoss	406042000	USD
CY2019	us-gaap	Interest Expense InterestExpense	137659000	USD
CY2019	us-gaap	Other Asset Impairment Charges OtherAssetImpairmentCharges	19741000	USD
CY2019	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	-5740000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	29580000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	213322000	USD
CY2019	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	USD
CY2019	us-gaap	Profit Loss ProfitLoss	213322000	USD
CY2019	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	14012000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	199310000	USD
CY2018	us-gaap	Revenues Revenues	1754268000	USD
CY2018	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	625610000	USD
CY2018	us-gaap	Costs And Expenses CostsAndExpenses	535293000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	196328000	USD
CY2018	us-gaap	Operating Income Loss OperatingIncomeLoss	397037000	USD
CY2018	us-gaap	Interest Expense InterestExpense	139975000	USD
CY2018	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	-1180000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-23667000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	279549000	USD
CY2018	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-6887000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	272662000	USD
CY2018	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	14220000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	258442000	USD
CY2017	us-gaap	Revenues Revenues	1680266000	USD
CY2017	us-gaap	Revenues Revenues	1680266000	USD
CY2017	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	563288000	USD
CY2017	us-gaap	Costs And Expenses CostsAndExpenses	511996000	USD
CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	188246000	USD
CY2017	us-gaap	Operating Income Loss OperatingIncomeLoss	416736000	USD
CY2017	us-gaap	Interest Expense InterestExpense	137102000	USD
CY2017	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	2108000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	73367000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	208375000	USD
CY2017	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-17099000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	191276000	USD
CY2017	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	14242000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	177034000	USD
CY2019Q4	bkh	Long Term Debt Before The Deduction Of Deferred Financing Costs LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts	3170489000	USD
CY2018Q4	bkh	Long Term Debt Before The Deduction Of Deferred Financing Costs LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts	2977568000	USD
CY2019Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	5743000	USD
CY2018Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	5743000	USD
CY2019Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	24650000	USD
CY2018Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	20990000	USD
CY2019Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	3140096000	USD
CY2018Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	2950835000	USD
CY2019Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	5743000	USD
CY2019Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	8435000	USD
CY2019Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	0	USD
CY2019Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	525000000	USD
CY2019Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	2855000	USD
CY2019Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	2635000000	USD
CY2019Q4	us-gaap	Deferred Finance Costs Noncurrent Net DeferredFinanceCostsNoncurrentNet	24650000	USD
CY2019	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	3242000	USD
CY2018	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	2829000	USD
CY2017	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	3349000	USD
CY2019Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	349500000	USD
CY2019Q4	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	30274000	USD
CY2018Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	185620000	USD
CY2018Q4	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	22311000	USD
CY2019Q4	bkh	Commercial Paper Maximum Borrowing Capacity CommercialPaperMaximumBorrowingCapacity	750000000	USD
CY2019Q4	bkh	Commercial Paper Maximum Borrowing Capacity CommercialPaperMaximumBorrowingCapacity	750000000	USD
CY2019	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	164000000	USD
CY2018Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	56800000	USD
CY2019	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	3445000	USD
CY2019	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	380000	USD
CY2019	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	2741000	USD
CY2019	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	1599000	USD
CY2019Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	64205000	USD
CY2017Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	52024000	USD
CY2018	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	152000	USD
CY2018	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	4000	USD
CY2018	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	2155000	USD
CY2018	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	2473000	USD
CY2018Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	56800000	USD
CY2019Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	1433000	USD
CY2019Q4	us-gaap	Derivative Collateral Obligation To Return Cash DerivativeCollateralObligationToReturnCash	1085000	USD
CY2019Q4	us-gaap	Derivative Assets DerivativeAssets	348000	USD
CY2019Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	5253000	USD
CY2019Q4	us-gaap	Derivative Liability Collateral Right To Reclaim Cash Offset DerivativeLiabilityCollateralRightToReclaimCashOffset	2908000	USD
CY2019Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	2345000	USD
CY2018Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	2927000	USD
CY2018Q4	us-gaap	Derivative Collateral Obligation To Return Cash DerivativeCollateralObligationToReturnCash	1408000	USD
CY2018Q4	us-gaap	Derivative Assets DerivativeAssets	1519000	USD
CY2018Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	6801000	USD
CY2018Q4	us-gaap	Derivative Liability Collateral Right To Reclaim Cash Offset DerivativeLiabilityCollateralRightToReclaimCashOffset	5794000	USD
CY2018Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	1007000	USD
CY2017Q3	bkh	At The Market Equity Offering Program Authorized Aggregate Value AtTheMarketEquityOfferingProgramAuthorizedAggregateValue	300000000	USD
CY2015Q4	us-gaap	Proceeds From Convertible Debt ProceedsFromConvertibleDebt	299000000	USD
CY2015Q4	bkh	Debt Instrument Convertible If Applicable Market Value Greater Than Reference Price Amount Used To Calculate Numberof Shares Numerator DebtInstrumentConvertibleIfApplicableMarketValueGreaterThanReferencePriceAmountUsedToCalculateNumberofSharesNumerator	50.00
CY2015Q4	bkh	Corporate Units Ownership Interest Percentage In Subordinated Notes CorporateUnitsOwnershipInterestPercentageInSubordinatedNotes	0.05
CY2015Q4	bkh	Debt Instrument Convertible Conversion Ratio Basis Stated Principal Amount DebtInstrumentConvertibleConversionRatioBasisStatedPrincipalAmount	1000	USD
CY2018Q4	bkh	Debt Instrument Convertible Consecutive Trading Daysfor Calculationof Applicable Market Value DebtInstrumentConvertibleConsecutiveTradingDaysforCalculationofApplicableMarketValue	P20D
CY2018Q4	bkh	Debt Instrument Convertible If Applicable Market Value Greater Than Reference Price Amount Used To Calculate Numberof Shares Numerator DebtInstrumentConvertibleIfApplicableMarketValueGreaterThanReferencePriceAmountUsedToCalculateNumberofSharesNumerator	50.00
CY2018Q4	us-gaap	Sale Of Stock Consideration Received On Transaction SaleOfStockConsiderationReceivedOnTransaction	299000000	USD
CY2018Q4	us-gaap	Sale Of Stock Number Of Shares Issued In Transaction SaleOfStockNumberOfSharesIssuedInTransaction	6372000	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	672049	shares
CY2019Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	12000000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P2Y
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	12095000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	12390000	USD
CY2017	us-gaap	Share Based Compensation ShareBasedCompensation	7626000	USD
CY2019Q4	us-gaap	Regulatory Assets RegulatoryAssets	271344000	USD
CY2018Q4	us-gaap	Regulatory Assets RegulatoryAssets	284235000	USD
CY2019	us-gaap	Stock Issued During Period Shares Treasury Stock Reissued StockIssuedDuringPeriodSharesTreasuryStockReissued	44000	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Share Based Liabilities Paid ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid	2860000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	5720000	USD
CY2018	us-gaap	Stock Issued During Period Shares Treasury Stock Reissued StockIssuedDuringPeriodSharesTreasuryStockReissued	0	shares
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Share Based Liabilities Paid ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid	0	USD
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	0	USD
CY2017	us-gaap	Stock Issued During Period Shares Treasury Stock Reissued StockIssuedDuringPeriodSharesTreasuryStockReissued	0	shares
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Share Based Liabilities Paid ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid	0	USD
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	0	USD
CY2019Q4	bkh	Sharebased Compensation Arrangementby Share Based Payment Award Performance Goal Percentileof Peer Group Performance SharebasedCompensationArrangementbyShareBasedPaymentAwardPerformanceGoalPercentileofPeerGroupPerformance	36.3
CY2019Q4	us-gaap	Common Stock Capital Shares Reserved For Future Issuance CommonStockCapitalSharesReservedForFutureIssuance	214967	shares
CY2019Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	25000000	shares
CY2019Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2016Q2	us-gaap	Variable Interest Entity Ownership Percentage VariableInterestEntityOwnershipPercentage	0.499
CY2016Q2	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	216000000	USD
CY2019	bkh	Numberof Daysthe Companyhasto Pay Distributionsof Net Income Attributableto Noncontrolling Interests NumberofDaystheCompanyhastoPayDistributionsofNetIncomeAttributabletoNoncontrollingInterests	P30D
CY2019Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	43282000	USD
CY2018Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	48776000	USD
CY2019Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	228062000	USD
CY2018Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	235459000	USD
CY2019Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	536652000	USD
CY2018Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	540794000	USD
CY2019Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	33507000	USD
CY2018Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	29810000	USD
CY2019Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	503145000	USD
CY2018Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	510984000	USD
CY2019	us-gaap	Lease Cost LeaseCost	1575000	USD
CY2019Q4	bkh	Operatingand Finance Lease Assets OperatingandFinanceLeaseAssets	5094000	USD
CY2019Q4	bkh	Operatingand Finance Lease Liabilities OperatingandFinanceLeaseLiabilities	5473000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	1263000	USD
CY2019	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	19000	USD
CY2019	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	93000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	2801000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	67000	USD
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P8Y
CY2019Q4	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P4Y
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0427
CY2019Q4	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.0419
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Remainder Of Fiscal Year LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear	1018000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Remainder Of Fiscal Year FinanceLeaseLiabilityPaymentsRemainderOfFiscalYear	126000	USD
CY2019Q4	bkh	Lease Liability Payments Remainderof Fiscal Year LeaseLiabilityPaymentsRemainderofFiscalYear	1144000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	865000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Due Year Two FinanceLeaseLiabilityPaymentsDueYearTwo	126000	USD
CY2019Q4	bkh	Lease Liability Payments Due Year Two LeaseLiabilityPaymentsDueYearTwo	991000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	743000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Due Year Three FinanceLeaseLiabilityPaymentsDueYearThree	126000	USD
CY2019Q4	bkh	Lease Liability Payments Due Year Three LeaseLiabilityPaymentsDueYearThree	869000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	718000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Due Year Four FinanceLeaseLiabilityPaymentsDueYearFour	126000	USD
CY2019Q4	bkh	Lease Liability Payments Due Year Four LeaseLiabilityPaymentsDueYearFour	844000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	714000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Due Year Five FinanceLeaseLiabilityPaymentsDueYearFive	10000	USD
CY2019Q4	bkh	Lease Liability Payments Due Year Five LeaseLiabilityPaymentsDueYearFive	724000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	2009000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Due After Year Five FinanceLeaseLiabilityPaymentsDueAfterYearFive	0	USD
CY2019Q4	bkh	Lease Liability Payments After Year Five LeaseLiabilityPaymentsAfterYearFive	2009000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	6067000	USD
CY2019Q4	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	514000	USD
CY2019Q4	bkh	Lease Liability Payments Due LeaseLiabilityPaymentsDue	6581000	USD
CY2019Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	1067000	USD
CY2019Q4	us-gaap	Finance Lease Liability Undiscounted Excess Amount FinanceLeaseLiabilityUndiscountedExcessAmount	41000	USD
CY2019Q4	bkh	Lease Liability Undiscounted Excess Amount LeaseLiabilityUndiscountedExcessAmount	1108000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	5000000	USD
CY2019Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	473000	USD
CY2019Q4	bkh	Lease Liability LeaseLiability	5473000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	1052000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	464000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	344000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	224000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	216000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	1776000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	4076000	USD
CY2019	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	2306000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received Remainder Of Fiscal Year LessorOperatingLeasePaymentsToBeReceivedRemainderOfFiscalYear	2227000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received Two Years LessorOperatingLeasePaymentsToBeReceivedTwoYears	1857000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received Three Years LessorOperatingLeasePaymentsToBeReceivedThreeYears	1793000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received Four Years LessorOperatingLeasePaymentsToBeReceivedFourYears	1799000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received Five Years LessorOperatingLeasePaymentsToBeReceivedFiveYears	1743000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received Thereafter LessorOperatingLeasePaymentsToBeReceivedThereafter	53739000	USD
CY2019Q4	us-gaap	Lessor Operating Lease Payments To Be Received LessorOperatingLeasePaymentsToBeReceived	63158000	USD
CY2017Q4	bkh	Tax Cutsand Jobs Actof2017 Changein Tax Rate Regulatory Liability TaxCutsandJobsActof2017ChangeinTaxRateRegulatoryLiability	309000000	USD
CY2017Q4	bkh	Tax Cutsand Jobs Actof2017 Changein Tax Rate Regulatory Liability TaxCutsandJobsActof2017ChangeinTaxRateRegulatoryLiability	309000000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-8578000	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	325000	USD
CY2017	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-6193000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	138000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	247000	USD
CY2017	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	-1432000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	-8440000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	572000	USD
CY2017	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	-7625000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	34551000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-25022000	USD
CY2017	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	76522000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	3469000	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	783000	USD
CY2017	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	4470000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	38020000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-24239000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	80992000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	29580000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-23667000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	73367000	USD
CY2018	us-gaap	Discontinued Operation Tax Effect Of Discontinued Operation DiscontinuedOperationTaxEffectOfDiscontinuedOperation	-2600000	USD
CY2017	us-gaap	Discontinued Operation Tax Effect Of Discontinued Operation DiscontinuedOperationTaxEffectOfDiscontinuedOperation	-8400000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Regulatory Assets And Liabilities DeferredTaxAssetsRegulatoryAssetsAndLiabilities	89754000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Regulatory Assets And Liabilities DeferredTaxAssetsRegulatoryAssetsAndLiabilities	92966000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Other DeferredTaxAssetsTaxCreditCarryforwardsOther	23261000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Other DeferredTaxAssetsTaxCreditCarryforwardsOther	20466000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	120624000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	139371000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards State And Local DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal	13537000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards State And Local DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal	16647000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Investments DeferredTaxAssetsInvestments	14030000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Investments DeferredTaxAssetsInvestments	16032000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards DeferredTaxAssetsTaxCreditCarryforwards	27139000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards DeferredTaxAssetsTaxCreditCarryforwards	23124000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	33395000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	39349000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	12063000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	11809000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	309677000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	336146000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	533292000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	529338000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	23586000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	32324000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Goodwill DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill	15875000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Goodwill DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill	602000	USD
CY2019Q4	bkh	Deferred Tax Liability State DeferredTaxLiabilityState	72911000	USD
CY2018Q4	bkh	Deferred Tax Liability State DeferredTaxLiabilityState	64095000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	24732000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	21118000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	670396000	USD
CY2018Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	647477000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	360719000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	311331000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2018	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.350
CY2019	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.015
CY2018	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.023
CY2017	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.009
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Minority Interest Income Expense EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense	0.012
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Minority Interest Income Expense EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense	0.013
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Minority Interest Income Expense EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense	0.018
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.039
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.020
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.017
CY2019	bkh	Effective Income Tax Rate Reconciliation Flow Through Accounting EffectiveIncomeTaxRateReconciliationFlowThroughAccounting	-0.024
CY2018	bkh	Effective Income Tax Rate Reconciliation Flow Through Accounting EffectiveIncomeTaxRateReconciliationFlowThroughAccounting	-0.016
CY2017	bkh	Effective Income Tax Rate Reconciliation Flow Through Accounting EffectiveIncomeTaxRateReconciliationFlowThroughAccounting	-0.011
CY2019	bkh	Effective Income Tax Reconciliationdueto Restructuring EffectiveIncomeTaxReconciliationduetoRestructuring	0
CY2018	bkh	Effective Income Tax Reconciliationdueto Restructuring EffectiveIncomeTaxReconciliationduetoRestructuring	-0.285
CY2017	bkh	Effective Income Tax Reconciliationdueto Restructuring EffectiveIncomeTaxReconciliationduetoRestructuring	0
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.016
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.001
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.026
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0.016
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	-0.027
CY2019	bkh	Effective Income Tax Reconciliation Amortization Of Excess Deferred Income Tax Expense EffectiveIncomeTaxReconciliationAmortizationOfExcessDeferredIncomeTaxExpense	-0.012
CY2018	bkh	Effective Income Tax Reconciliation Amortization Of Excess Deferred Income Tax Expense EffectiveIncomeTaxReconciliationAmortizationOfExcessDeferredIncomeTaxExpense	-0.007
CY2017	bkh	Effective Income Tax Reconciliation Amortization Of Excess Deferred Income Tax Expense EffectiveIncomeTaxReconciliationAmortizationOfExcessDeferredIncomeTaxExpense	0
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.122
CY2018	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	-0.093
CY2017	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.260
CY2018	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	4000000.0	USD
CY2017	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	7600000	USD
CY2016Q4	us-gaap	Liability For Uncertain Tax Positions Noncurrent LiabilityForUncertainTaxPositionsNoncurrent	3592000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	358000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	5713000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	5026000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0	USD
CY2017Q4	us-gaap	Liability For Uncertain Tax Positions Noncurrent LiabilityForUncertainTaxPositionsNoncurrent	3263000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	251000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	417000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	486000	USD
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CY2018	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	14730000	USD
CY2017	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-1775000	USD
CY2019	us-gaap	Defined Contribution Plan Maximum Annual Contributions Per Employee Percent DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent	0.50
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CY2019Q4	us-gaap	Defined Benefit Plan Plan Assets Target Allocation Percentage DefinedBenefitPlanPlanAssetsTargetAllocationPercentage	1
CY2018Q4	us-gaap	Defined Benefit Plan Plan Assets Target Allocation Percentage DefinedBenefitPlanPlanAssetsTargetAllocationPercentage	1
CY2019Q4	us-gaap	Defined Benefit Plan Expected Future Employer Contributions Next Fiscal Year DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear	13000000	USD
CY2018Q4	us-gaap	Business Acquisition Percentage Of Voting Interests Acquired BusinessAcquisitionPercentageOfVotingInterestsAcquired	0.50
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CY2018	us-gaap	Disposal Group Including Discontinued Operation Revenue DisposalGroupIncludingDiscontinuedOperationRevenue	5897000	USD
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CY2018	us-gaap	Disposal Group Including Discontinued Operation Operating Expense DisposalGroupIncludingDiscontinuedOperationOperatingExpense	11014000	USD
CY2017	us-gaap	Disposal Group Including Discontinued Operation Operating Expense DisposalGroupIncludingDiscontinuedOperationOperatingExpense	22872000	USD
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CY2018	us-gaap	Disposal Group Including Discontinued Operation Depreciation And Amortization DisposalGroupIncludingDiscontinuedOperationDepreciationAndAmortization	1300000	USD
CY2017	us-gaap	Disposal Group Including Discontinued Operation Depreciation And Amortization DisposalGroupIncludingDiscontinuedOperationDepreciationAndAmortization	7521000	USD
CY2018	bkh	Disposal Group Including Discontinued Operations Impairmentof Longlived Assets DisposalGroupIncludingDiscontinuedOperationsImpairmentofLonglivedAssets	0	USD
CY2017	bkh	Disposal Group Including Discontinued Operations Impairmentof Longlived Assets DisposalGroupIncludingDiscontinuedOperationsImpairmentofLonglivedAssets	20385000	USD
CY2018	bkh	Disposal Group Including Discontinued Operations Total Operating Expenses DisposalGroupIncludingDiscontinuedOperationsTotalOperatingExpenses	15573000	USD
CY2017	bkh	Disposal Group Including Discontinued Operations Total Operating Expenses DisposalGroupIncludingDiscontinuedOperationsTotalOperatingExpenses	50778000	USD
CY2018	us-gaap	Disposal Group Including Discontinued Operation Operating Income Loss DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss	-9676000	USD
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CY2019Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	USD
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CY2019Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	USD
CY2019Q1	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3554000	USD
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CY2019Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3655000	USD
CY2019Q4	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3693000	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	103808000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	14583000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	11740000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	69179000	USD
CY2019Q1	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	103808000	USD
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CY2019Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	USD
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CY2019Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	USD
CY2019Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	103808000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	14583000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	11740000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	69179000	USD
CY2019Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	1.73
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CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.73
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CY2018Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-857000	USD
CY2018Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-1260000	USD
CY2018Q1	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3630000	USD
CY2018Q2	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	2823000	USD
CY2018Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3994000	USD
CY2018Q4	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3773000	USD
CY2018Q1	us-gaap	Net Income Loss NetIncomeLoss	133004000	USD
CY2018Q2	us-gaap	Net Income Loss NetIncomeLoss	21917000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	16950000	USD
CY2018Q4	us-gaap	Net Income Loss NetIncomeLoss	86571000	USD
CY2018Q1	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	135347000	USD
CY2018Q2	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	24344000	USD
CY2018Q3	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	17807000	USD
CY2018Q4	us-gaap	Net Income Loss From Continuing Operations Available To Common Shareholders Basic NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic	87831000	USD
CY2018Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-2343000	USD
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CY2018Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-1260000	USD
CY2018Q1	us-gaap	Net Income Loss NetIncomeLoss	133004000	USD
CY2018Q2	us-gaap	Net Income Loss NetIncomeLoss	21917000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	16950000	USD
CY2018Q4	us-gaap	Net Income Loss NetIncomeLoss	86571000	USD
CY2018Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	2.54
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CY2018Q1	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	-0.05
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CY2018Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.49
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CY2018Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.32
CY2018Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.50
CY2018Q1	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	2.50
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CY2018Q3	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.32
CY2018Q4	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	1.51
CY2018Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.04
CY2018Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.05
CY2018Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.02
CY2018Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.02
CY2018Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.46
CY2018Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.40
CY2018Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.31
CY2018Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.49

Files In Submission

Name	View Source	Status
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$BKH
BLACK HILLS CORP /SD/ Stock $bkh

2019 Q4 Form 10-K Financial Statement

#000113046420000006 Filed on February 14, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BKH BLACK HILLS CORP /SD/ Stock $bkh

2019 Q4 Form 10-K Financial Statement

#000113046420000006 Filed on February 14, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BKH
BLACK HILLS CORP /SD/ Stock $bkh