$BKH
BLACK HILLS CORP /SD/ Stock $bkh

$bkh Overview Financials Valuation SEC Filings Company Website

2017 Q4 Form 10-K Financial Statement

#000113046419000012 Filed on February 19, 2019

Income Statement

Concept	2017 Q4	2017 Q3	2017 Q2
Revenue	$455.3M	$335.6M	$341.8M
YoY Change	-0.02%	3.54%	7.56%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$47.60M	$47.11M	$46.83M
YoY Change	36.39%	-3.71%	-1.01%
% of Gross Profit
Operating Expenses	$338.1M	$256.1M	$272.0M
YoY Change	29.64%	-7.02%	-6.24%
Operating Profit	$117.2M	$79.56M	$69.80M
YoY Change	6.22%	12.3%	9.53%
Interest Expense	-$34.60M	-$34.10M	-$33.90M
YoY Change	-4.16%	-3.4%	3.99%
% of Operating Profit	-29.52%	-42.86%	-48.57%
Other Income/Expense, Net	$100.0K	-$33.18M	-$33.22M
YoY Change	-85.71%	-2.06%	70574.47%
Pretax Income	$82.70M	$46.38M	$36.58M
YoY Change	-38.05%	89.07%	918.35%
Income Tax	-$294.2M	$13.48M	$10.65M
% Of Pretax Income	-355.74%	29.06%	29.12%
Net Earnings	$50.70M	$31.60M	$25.31M
YoY Change	178.57%	76.68%	670.97%
Net Earnings / Revenue	11.14%	9.42%	7.4%
Basic Earnings Per Share	$0.95	$0.52	$0.42
Diluted Earnings Per Share	$0.92	$0.50	$0.40
COMMON SHARES
Basic Shares Outstanding	53.48M shares	53.24M shares	53.23M shares
Diluted Shares Outstanding		55.43M shares	55.38M shares

Balance Sheet

Concept	2017 Q4	2017 Q3	2017 Q2
SHORT-TERM ASSETS
Cash & Short-Term Investments	$15.40M	$13.50M	$11.60M
YoY Change	14.07%	-78.57%	-90.07%
Cash & Equivalents	$15.42M	$13.45M	$11.53M
Short-Term Investments
Other Short-Term Assets	$25.37M	$25.59M	$20.77M
YoY Change	6.01%	-14.8%	-32.25%
Inventory	$113.3M	$122.9M	$95.49M
Prepaid Expenses
Receivables	$248.3M	$150.3M	$166.8M
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$570.8M	$385.0M	$359.3M
YoY Change	22.27%	-0.52%	-7.6%
LONG-TERM ASSETS
Property, Plant & Equipment	$4.541B	$4.499B	$4.459B
YoY Change	3.54%	0.75%	1.56%
Goodwill	$1.299B	$1.299B	$1.299B
YoY Change	0.0%	-0.07%	-0.31%
Intangibles	$7.559M	$7.765M	$7.972M
YoY Change	-9.93%	-13.18%	-13.01%
Long-Term Investments	$13.10M	$12.90M	$12.80M
YoY Change	3.97%	4.03%	3.23%
Other Assets	$10.15M	$11.63M	$13.59M
YoY Change	-11.81%	-9.17%	-11.94%
Total Long-Term Assets	$6.088B	$6.179B	$1.565B
YoY Change	288.5%	296.95%	1.07%
TOTAL ASSETS
Total Short-Term Assets	$570.8M	$385.0M	$359.3M
Total Long-Term Assets	$6.088B	$6.179B	$1.565B
Total Assets	$6.659B	$6.564B	$6.510B
YoY Change	1.79%	2.22%	2.68%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$160.9M	$94.79M	$99.30M
YoY Change	5.76%	-14.32%	-13.81%
Accrued Expenses	$219.5M	$206.8M	$191.8M
YoY Change	-6.83%	-9.51%	-12.12%
Deferred Revenue
YoY Change
Short-Term Debt	$211.3M	$225.2M	$108.0M
YoY Change	118.74%	200.23%	43.97%
Long-Term Debt Due	$5.743M	$5.743M	$5.743M
YoY Change	0.0%	0.0%	-99.38%
Total Short-Term Liabilities	$649.1M	$554.3M	$438.9M
YoY Change	22.95%	23.26%	-68.94%
LONG-TERM LIABILITIES
Long-Term Debt	$3.109B	$3.110B	$3.160B
YoY Change	-3.17%	-3.17%	42.27%
Other Long-Term Liabilities	$105.7M	$114.0M	$112.6M
YoY Change	-8.76%	-19.16%	-7.76%
Total Long-Term Liabilities	$1.080B	$1.104B	$1.121B
YoY Change	1.12%	6.8%	9.7%
TOTAL LIABILITIES
Total Short-Term Liabilities	$649.1M	$554.3M	$438.9M
Total Long-Term Liabilities	$1.080B	$1.104B	$1.121B
Total Liabilities	$1.729B	$1.658B	$1.559B
YoY Change	8.34%	11.79%	-35.94%
SHAREHOLDERS EQUITY
Retained Earnings	$548.6M	$516.4M	$512.5M
YoY Change	19.8%	11.75%	9.06%
Common Stock	$53.58M	$53.53M	$53.51M
YoY Change	0.34%	0.74%	2.32%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$2.306M	$2.448M	$2.325M
YoY Change	191.53%	111.95%	138.46%
Treasury Stock Shares	39.06K shares	41.46K shares	39.33K shares
Shareholders Equity	$1.709B	$1.683B	$1.676B
YoY Change
Total Liabilities & Shareholders Equity	$6.659B	$6.564B	$6.510B
YoY Change	1.79%	2.22%	2.68%

Cashflow Statement

Concept	2017 Q4	2017 Q3	2017 Q2
OPERATING ACTIVITIES
Net Income	$50.70M	$31.60M	$25.31M
YoY Change	178.57%	76.68%	670.97%
Depreciation, Depletion And Amortization	$47.60M	$47.11M	$46.83M
YoY Change	36.39%	-3.71%	-1.01%
Cash From Operating Activities	$108.9M	$56.50M	$116.1M
YoY Change	-2.16%	-515.44%	29.43%
INVESTING ACTIVITIES
Capital Expenditures	-$87.20M	-$84.50M	-$87.80M
YoY Change	-27.87%	-37.03%	-24.31%
Acquisitions
YoY Change
Other Investing Activities	$26.00M	-$7.900M	-$6.300M
YoY Change	-398.85%	3850.0%	-181.82%
Cash From Investing Activities	-$61.10M	-$92.50M	-$94.10M
YoY Change	-52.82%	-31.23%	-13.03%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-45.60M	38.00M	-21.50M
YoY Change	-45700.0%	-51.72%	-122.97%
NET CHANGE
Cash From Operating Activities	108.9M	56.50M	116.1M
Cash From Investing Activities	-61.10M	-92.50M	-94.10M
Cash From Financing Activities	-45.60M	38.00M	-21.50M
Net Change In Cash	2.200M	2.000M	500.0K
YoY Change	-112.15%	-102.88%	-99.33%
FREE CASH FLOW
Cash From Operating Activities	$108.9M	$56.50M	$116.1M
Capital Expenditures	-$87.20M	-$84.50M	-$87.80M
Free Cash Flow	$196.1M	$141.0M	$203.9M
YoY Change	-15.55%	16.92%	-0.88%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
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CY2017Q3	bkh	At The Market Equity Offering Program Authorized Aggregate Value AtTheMarketEquityOfferingProgramAuthorizedAggregateValue	300000000	USD
CY2018	bkh	Business Acquisition Pro Forma Combined Federaland Stateincome Tax Rate BusinessAcquisitionProFormaCombinedFederalandStateincomeTaxRate	0.37
CY2017Q1	bkh	Business Combination Acquisition Related Costs Net Of Tax BusinessCombinationAcquisitionRelatedCostsNetOfTax	900000	USD
CY2017Q2	bkh	Business Combination Acquisition Related Costs Net Of Tax BusinessCombinationAcquisitionRelatedCostsNetOfTax	300000	USD
CY2017Q3	bkh	Business Combination Acquisition Related Costs Net Of Tax BusinessCombinationAcquisitionRelatedCostsNetOfTax	200000	USD
CY2017Q4	bkh	Business Combination Acquisition Related Costs Net Of Tax BusinessCombinationAcquisitionRelatedCostsNetOfTax	1300000	USD
CY2016	bkh	Business Combination Consideration Transferred Netof Long Term Debtand Cash Acquired BusinessCombinationConsiderationTransferredNetofLongTermDebtandCashAcquired	1124238000	USD
CY2017	bkh	Business Combination Consideration Transferred Netof Long Term Debtand Cash Acquired BusinessCombinationConsiderationTransferredNetofLongTermDebtandCashAcquired	0	USD
CY2018	bkh	Business Combination Consideration Transferred Netof Long Term Debtand Cash Acquired BusinessCombinationConsiderationTransferredNetofLongTermDebtandCashAcquired	0	USD
CY2016Q1	bkh	Business Combination Consideration Transferred Netof Long Term Debtand Cash Acquired Before Working Capital Adjustment BusinessCombinationConsiderationTransferredNetofLongTermDebtandCashAcquiredBeforeWorkingCapitalAdjustment	1135000000	USD
CY2018Q4	bkh	Commercial Paper Maximum Borrowing Capacity CommercialPaperMaximumBorrowingCapacity	750000000	USD
CY2015Q4	bkh	Corporate Units Ownership Interest Percentage In Subordinated Notes CorporateUnitsOwnershipInterestPercentageInSubordinatedNotes	0.05
CY2017Q4	bkh	Customer Depositsand Prepayments CustomerDepositsandPrepayments	44420000	USD
CY2018Q4	bkh	Customer Depositsand Prepayments CustomerDepositsandPrepayments	43574000	USD
CY2018Q4	bkh	Debt Instrument Convertible Consecutive Trading Daysfor Calculationof Applicable Market Value DebtInstrumentConvertibleConsecutiveTradingDaysforCalculationofApplicableMarketValue	P20D
CY2015Q4	bkh	Debt Instrument Convertible Conversion Ratio Basis Stated Principal Amount DebtInstrumentConvertibleConversionRatioBasisStatedPrincipalAmount	1000	USD
CY2015Q4	bkh	Debt Instrument Convertible If Applicable Market Value Greater Than Reference Price Amount Used To Calculate Numberof Shares Numerator DebtInstrumentConvertibleIfApplicableMarketValueGreaterThanReferencePriceAmountUsedToCalculateNumberofSharesNumerator	50
CY2018Q4	bkh	Debt Instrument Convertible If Applicable Market Value Greater Than Reference Price Amount Used To Calculate Numberof Shares Numerator DebtInstrumentConvertibleIfApplicableMarketValueGreaterThanReferencePriceAmountUsedToCalculateNumberofSharesNumerator	50.00
CY2017Q4	bkh	Deferred Tax Liability State DeferredTaxLiabilityState	58930000	USD
CY2018Q4	bkh	Deferred Tax Liability State DeferredTaxLiabilityState	64095000	USD
CY2018	bkh	Defined Contribution Plan Employee Vesting Period DefinedContributionPlanEmployeeVestingPeriod	P5Y
CY2016	bkh	Discounted Present Value Rate Usedin Estimating Future Net Revenues Oiland Gas Industry DiscountedPresentValueRateUsedinEstimatingFutureNetRevenuesOilandGasIndustry	0.1
CY2016	bkh	Disposal Group Including Discontinued Operations Corporate Expenses DisposalGroupIncludingDiscontinuedOperationsCorporateExpenses	10924000	USD
CY2017	bkh	Disposal Group Including Discontinued Operations Corporate Expenses DisposalGroupIncludingDiscontinuedOperationsCorporateExpenses	9577000	USD
CY2016	bkh	Disposal Group Including Discontinued Operations Impairmentof Longlived Assets DisposalGroupIncludingDiscontinuedOperationsImpairmentofLonglivedAssets	106957000	USD
CY2017	bkh	Disposal Group Including Discontinued Operations Impairmentof Longlived Assets DisposalGroupIncludingDiscontinuedOperationsImpairmentofLonglivedAssets	20385000	USD
CY2018	bkh	Disposal Group Including Discontinued Operations Impairmentof Longlived Assets DisposalGroupIncludingDiscontinuedOperationsImpairmentofLonglivedAssets	0	USD
CY2016	bkh	Disposal Group Including Discontinued Operations Interest Income Expense Net DisposalGroupIncludingDiscontinuedOperationsInterestIncomeExpenseNet	698000	USD
CY2017	bkh	Disposal Group Including Discontinued Operations Interest Income Expense Net DisposalGroupIncludingDiscontinuedOperationsInterestIncomeExpenseNet	181000	USD
CY2018	bkh	Disposal Group Including Discontinued Operations Interest Income Expense Net DisposalGroupIncludingDiscontinuedOperationsInterestIncomeExpenseNet	-19000	USD
CY2016	bkh	Disposal Group Including Discontinued Operations Other Income Expensenet DisposalGroupIncludingDiscontinuedOperationsOtherIncomeExpensenet	110000	USD
CY2017	bkh	Disposal Group Including Discontinued Operations Other Income Expensenet DisposalGroupIncludingDiscontinuedOperationsOtherIncomeExpensenet	-297000	USD
CY2018	bkh	Disposal Group Including Discontinued Operations Other Income Expensenet DisposalGroupIncludingDiscontinuedOperationsOtherIncomeExpensenet	190000	USD
CY2016	bkh	Disposal Group Including Discontinued Operations Total Operating Expenses DisposalGroupIncludingDiscontinuedOperationsTotalOperatingExpenses	147654000	USD
CY2017	bkh	Disposal Group Including Discontinued Operations Total Operating Expenses DisposalGroupIncludingDiscontinuedOperationsTotalOperatingExpenses	50778000	USD
CY2018	bkh	Disposal Group Including Discontinued Operations Total Operating Expenses DisposalGroupIncludingDiscontinuedOperationsTotalOperatingExpenses	15573000	USD
CY2016	bkh	Effective Income Tax Rate Reconciliation Allowance For Other Funds Used During Construction Equity EffectiveIncomeTaxRateReconciliationAllowanceForOtherFundsUsedDuringConstructionEquity	-0.005
CY2017	bkh	Effective Income Tax Rate Reconciliation Allowance For Other Funds Used During Construction Equity EffectiveIncomeTaxRateReconciliationAllowanceForOtherFundsUsedDuringConstructionEquity	-0.002
CY2018	bkh	Effective Income Tax Rate Reconciliation Allowance For Other Funds Used During Construction Equity EffectiveIncomeTaxRateReconciliationAllowanceForOtherFundsUsedDuringConstructionEquity	0.000
CY2016	bkh	Effective Income Tax Rate Reconciliation Flow Through Accounting EffectiveIncomeTaxRateReconciliationFlowThroughAccounting	-0.021
CY2017	bkh	Effective Income Tax Rate Reconciliation Flow Through Accounting EffectiveIncomeTaxRateReconciliationFlowThroughAccounting	-0.011
CY2018	bkh	Effective Income Tax Rate Reconciliation Flow Through Accounting EffectiveIncomeTaxRateReconciliationFlowThroughAccounting	-0.016
CY2016	bkh	Effective Income Tax Reconciliation Net Operating Loss Carryback EffectiveIncomeTaxReconciliationNetOperatingLossCarryback	0.000
CY2017	bkh	Effective Income Tax Reconciliation Net Operating Loss Carryback EffectiveIncomeTaxReconciliationNetOperatingLossCarryback	-0.007
CY2018	bkh	Effective Income Tax Reconciliation Net Operating Loss Carryback EffectiveIncomeTaxReconciliationNetOperatingLossCarryback	0.000
CY2016	bkh	Effective Income Tax Reconciliationdueto Restructuring EffectiveIncomeTaxReconciliationduetoRestructuring	0.000
CY2017	bkh	Effective Income Tax Reconciliationdueto Restructuring EffectiveIncomeTaxReconciliationduetoRestructuring	0.000
CY2018	bkh	Effective Income Tax Reconciliationdueto Restructuring EffectiveIncomeTaxReconciliationduetoRestructuring	-0.285
CY2018	bkh	Electric Generation Capacity Megawatts ElectricGenerationCapacityMegawatts	200	MW
CY2016	bkh	Excess Deferred Amortization ExcessDeferredAmortization	0	USD
CY2017	bkh	Excess Deferred Amortization ExcessDeferredAmortization	0	USD
CY2018	bkh	Excess Deferred Amortization ExcessDeferredAmortization	1727000	USD
CY2016	bkh	Finite Lived Intangible Asset Purchase Accounting Adjustments FiniteLivedIntangibleAssetPurchaseAccountingAdjustments	5522000	USD
CY2017	bkh	Finite Lived Intangible Asset Purchase Accounting Adjustments FiniteLivedIntangibleAssetPurchaseAccountingAdjustments	0	USD
CY2018	bkh	Finite Lived Intangible Asset Purchase Accounting Adjustments FiniteLivedIntangibleAssetPurchaseAccountingAdjustments	7602000	USD
CY2016	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	499132000	USD
CY2017	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	563288000	USD
CY2018	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	625610000	USD
CY2016	bkh	Investment Tax Credit Amortization InvestmentTaxCreditAmortization	52000	USD
CY2017	bkh	Investment Tax Credit Amortization InvestmentTaxCreditAmortization	45000	USD
CY2018	bkh	Investment Tax Credit Amortization InvestmentTaxCreditAmortization	32000	USD
CY2017Q4	bkh	Long Term Debt Before The Deduction Of Deferred Financing Costs LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts	3133621000	USD
CY2018Q4	bkh	Long Term Debt Before The Deduction Of Deferred Financing Costs LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts	2977568000	USD
CY2016	bkh	Non Cash Revision To Capitalized Asset Retirement Costs NonCashRevisionToCapitalizedAssetRetirementCosts	8577000	USD
CY2017	bkh	Non Cash Revision To Capitalized Asset Retirement Costs NonCashRevisionToCapitalizedAssetRetirementCosts	3198000	USD
CY2018	bkh	Non Cash Revision To Capitalized Asset Retirement Costs NonCashRevisionToCapitalizedAssetRetirementCosts	2625000	USD
CY2018	bkh	Numberof Daysthe Companyhasto Pay Distributionsof Net Income Attributableto Noncontrolling Interests NumberofDaystheCompanyhastoPayDistributionsofNetIncomeAttributabletoNoncontrollingInterests	P30D
CY2018	bkh	Numberof Megawatts Capacity Sold NumberofMegawattsCapacitySold	40	MW
CY2018Q4	bkh	Numberof States That Have Received State Utility Commission Approvalsto Providethe Benefitsof Federal Tax Reformto Utility Customers NumberofStatesThatHaveReceivedStateUtilityCommissionApprovalstoProvidetheBenefitsofFederalTaxReformtoUtilityCustomers	6	State
CY2016	bkh	Operating Expense Maintenance Operationsand Other Costsand Expense OperatingExpenseMaintenanceOperationsandOtherCostsandExpense	426603000	USD
CY2017	bkh	Operating Expense Maintenance Operationsand Other Costsand Expense OperatingExpenseMaintenanceOperationsandOtherCostsandExpense	454605000	USD
CY2018	bkh	Operating Expense Maintenance Operationsand Other Costsand Expense OperatingExpenseMaintenanceOperationsandOtherCostsandExpense	481706000	USD
CY2015Q4	bkh	Proceeds From Issuance Of Common Stockand Sale Of Interest In Corporate Units ProceedsFromIssuanceOfCommonStockandSaleOfInterestInCorporateUnits	536000000	USD
CY2017	bkh	Property Plantand Equipment Including New Asset Acquisitions Gross Period Increase Decrease PropertyPlantandEquipmentIncludingNewAssetAcquisitionsGrossPeriodIncreaseDecrease	360911000	USD
CY2018	bkh	Property Plantand Equipment Including New Asset Acquisitions Gross Period Increase Decrease PropertyPlantandEquipmentIncludingNewAssetAcquisitionsGrossPeriodIncreaseDecrease	504826000	USD
CY2016	bkh	Public Utilities Allowance For Funds Used During Construction Borrowed Interest Costs Capitalized PublicUtilitiesAllowanceForFundsUsedDuringConstructionBorrowedInterestCostsCapitalized	2981000	USD
CY2017	bkh	Public Utilities Allowance For Funds Used During Construction Borrowed Interest Costs Capitalized PublicUtilitiesAllowanceForFundsUsedDuringConstructionBorrowedInterestCostsCapitalized	2415000	USD
CY2018	bkh	Public Utilities Allowance For Funds Used During Construction Borrowed Interest Costs Capitalized PublicUtilitiesAllowanceForFundsUsedDuringConstructionBorrowedInterestCostsCapitalized	2104000	USD
CY2017Q4	bkh	Public Utilities Numberof Rate Review Requests Filed PublicUtilitiesNumberofRateReviewRequestsFiled	3	utility
CY2018	bkh	Reclassificationfrom Legal Entity Restructuring ReclassificationfromLegalEntityRestructuring	6519000	USD
CY2018	bkh	Revenue Refunded To Customers As A Result Of The Tcja Tax Benefits RevenueRefundedToCustomersAsAResultOfTheTCJATaxBenefits	19000000	USD
CY2018Q4	bkh	Sharebased Compensation Arrangementby Share Based Payment Award Performance Goal Percentileof Peer Group Performance SharebasedCompensationArrangementbyShareBasedPaymentAwardPerformanceGoalPercentileofPeerGroupPerformance	0.748
CY2017Q4	bkh	Tax Cutsand Jobs Actof2017 Changein Tax Rate Income Tax Expense Benefit TaxCutsandJobsActof2017ChangeinTaxRateIncomeTaxExpenseBenefit	-7600000	USD
CY2017	bkh	Tax Cutsand Jobs Actof2017 Incomplete Accounting Provisional Income Tax Expense Benefit TaxCutsandJobsActof2017IncompleteAccountingProvisionalIncomeTaxExpenseBenefit	309000000	USD
CY2017	bkh	Tax Cutsand Jobs Actof2017 Reclassificationfrom Aoc Ito Retained Earnings TaxCutsandJobsActof2017ReclassificationfromAOCItoRetainedEarnings	0	USD
CY2018	bkh	Tax Cutsand Jobs Actof2017 Reclassificationfrom Aoc Ito Retained Earnings TaxCutsandJobsActof2017ReclassificationfromAOCItoRetainedEarnings	740000	USD
CY2016	bkh	Total Other Income Expense TotalOtherIncomeExpense	-130287000	USD
CY2017	bkh	Total Other Income Expense TotalOtherIncomeExpense	-134994000	USD
CY2018	bkh	Total Other Income Expense TotalOtherIncomeExpense	-141155000	USD
CY2018	dei	Amendment Flag AmendmentFlag	false
CY2018	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2018	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2018	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2018
CY2018	dei	Document Period End Date DocumentPeriodEndDate	2018-12-31
CY2018	dei	Document Type DocumentType	10-K
CY2018	dei	Entity Central Index Key EntityCentralIndexKey	0001130464
CY2019Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	60003964.507	shares
CY2018	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2018	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2018	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2018Q2	dei	Entity Public Float EntityPublicFloat	3239030444	USD
CY2018	dei	Entity Registrant Name EntityRegistrantName	BLACK HILLS CORP /SD/
CY2018	dei	Entity Shell Company EntityShellCompany	false
CY2018	dei	Entity Small Business EntitySmallBusiness	false
CY2018	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2018	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
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CY2018Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	210609000	USD
CY2017Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	248330000	USD
CY2018Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	269153000	USD
CY2017Q4	us-gaap	Accrual For Taxes Other Than Income Taxes Current AccrualForTaxesOtherThanIncomeTaxesCurrent	42029000	USD
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CY2017Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	1022000	USD
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CY2017Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	219462000	USD
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CY2017Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1026088000	USD
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CY2016Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-34883000	USD
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CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-26916000	USD
CY2017Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	1150285000	USD
CY2018Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	1450569000	USD
CY2017	us-gaap	Adjustment To Additional Paid In Capital Income Tax Effect From Share Based Compensation Net AdjustmentToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet	3717000	USD
CY2016	us-gaap	Adjustments To Additional Paid In Capital Stock Issued Issuance Costs AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts	1566000	USD
CY2017	us-gaap	Adjustments To Additional Paid In Capital Stock Issued Issuance Costs AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts	189000	USD
CY2018	us-gaap	Adjustments To Additional Paid In Capital Stock Issued Issuance Costs AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts	15000	USD
CY2017Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	3081000	USD
CY2018Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	3209000	USD
CY2016	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	3861000	USD
CY2017	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	3349000	USD
CY2018	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	2829000	USD
CY2016	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	6180000	USD
CY2017	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	8261000	USD
CY2018	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	7845000	USD
CY2016	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	510000	USD
CY2017	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	833000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	824000	USD
CY2016	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	3000	shares
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CY2018	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	16000	shares
CY2016Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	46876000	USD
CY2017Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	52024000	USD
CY2018Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	56800000	USD
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CY2018	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	2155000	USD
CY2017	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	0	USD
CY2018	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	152000	USD
CY2017	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	111000	USD
CY2018	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	4000	USD
CY2017	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	3198000	USD
CY2018	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	2473000	USD
CY2017Q4	us-gaap	Assets Assets	6658902000	USD
CY2018Q4	us-gaap	Assets Assets	6963327000	USD
CY2017Q4	us-gaap	Assets Current AssetsCurrent	570782000	USD
CY2018Q4	us-gaap	Assets Current AssetsCurrent	503833000	USD
CY2017Q4	us-gaap	Assets Noncurrent Other Than Noncurrent Investments And Property Plant And Equipment AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment	1533600000	USD
CY2018Q4	us-gaap	Assets Noncurrent Other Than Noncurrent Investments And Property Plant And Equipment AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment	1563602000	USD
CY2017Q4	us-gaap	Assets Of Disposal Group Including Discontinued Operation AssetsOfDisposalGroupIncludingDiscontinuedOperation	42468000	USD
CY2017Q4	us-gaap	Assets Of Disposal Group Including Discontinued Operation Current AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent	84242000	USD
CY2018Q4	us-gaap	Assets Of Disposal Group Including Discontinued Operation Current AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent	0	USD
CY2017	us-gaap	Capital Expenditure Discontinued Operations CapitalExpenditureDiscontinuedOperations	23222000	USD
CY2018	us-gaap	Capital Expenditure Discontinued Operations CapitalExpenditureDiscontinuedOperations	2402000	USD
CY2016	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	27034000	USD
CY2017	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	28191000	USD
CY2018	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	69017000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	15420000	USD
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	20776000	USD
CY2015Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	442480000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	15792000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	18240000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	24145000	USD
CY2016	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-426688000	USD
CY2017	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	2448000	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	5905000	USD
CY2016	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	-8413000	USD
CY2017	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	7881000	USD
CY2018	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	20385000	USD
CY2016	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	2744000	USD
CY2017	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	19231000	USD
CY2018	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	-5516000	USD
CY2017Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2018Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2018Q4	us-gaap	Common Stock Capital Shares Reserved For Future Issuance CommonStockCapitalSharesReservedForFutureIssuance	253418	shares
CY2016	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.68
CY2017	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.81
CY2018	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.93
CY2017Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	1
CY2018Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	1
CY2017Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	100000000	shares
CY2018Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	100000000	shares
CY2017Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	53579986	shares
CY2017Q4	us-gaap	Common Stock Value CommonStockValue	53580000	USD
CY2018Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	60048567	shares
CY2018Q4	us-gaap	Common Stock Value CommonStockValue	60049000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	47142000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	177715000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	265469000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	56803000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	191957000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	279689000	USD
CY2017Q4	us-gaap	Contributions In Aid Of Construction ContributionsInAidOfConstruction	1552000	USD
CY2018Q4	us-gaap	Contributions In Aid Of Construction ContributionsInAidOfConstruction	1485000	USD
CY2016	us-gaap	Costs And Expenses CostsAndExpenses	528070000	USD
CY2017	us-gaap	Costs And Expenses CostsAndExpenses	511996000	USD
CY2018	us-gaap	Costs And Expenses CostsAndExpenses	535293000	USD
CY2016	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-21806000	USD
CY2017	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-6193000	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	325000	USD
CY2016	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	-23603000	USD
CY2017	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	-7625000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	572000	USD
CY2016	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	-1797000	USD
CY2017	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	-1432000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	247000	USD
CY2016	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	78997000	USD
CY2017	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	76567000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-23295000	USD
CY2017Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	18478000	USD
CY2018Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	20990000	USD
CY2018Q4	us-gaap	Deferred Finance Costs Noncurrent Net DeferredFinanceCostsNoncurrentNet	20990000	USD
CY2016	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	82704000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	80992000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-24239000	USD
CY2017Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	666702000	USD
CY2018Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	647477000	USD
CY2016	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	3759000	USD
CY2017	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	4470000	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	815000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	330182000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	336146000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	155276000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	139371000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	74561000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	101579000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Regulatory Assets And Liabilities DeferredTaxAssetsRegulatoryAssetsAndLiabilities	90742000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Regulatory Assets And Liabilities DeferredTaxAssetsRegulatoryAssetsAndLiabilities	92966000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits	18724000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	9121000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	11809000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	336520000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits	14039000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	311331000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Deferred Expense DeferredTaxLiabilitiesDeferredExpense	16063000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Deferred Expense DeferredTaxLiabilitiesDeferredExpense	13351000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Goodwill DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill	46392000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Goodwill DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill	602000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	336520000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	311331000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	8298000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	7767000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	510774000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	529338000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	26245000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	32324000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Expected Future Employer Contributions Next Fiscal Year DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear	13000000	USD
CY2017Q4	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
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CY2018	us-gaap	Defined Contribution Plan Maximum Annual Contributions Per Employee Percent DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent	0.5
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CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	188246000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	196328000	USD
CY2017Q4	us-gaap	Derivative Assets DerivativeAssets	304000	USD
CY2018Q4	us-gaap	Derivative Assets DerivativeAssets	1519000	USD
CY2017Q4	us-gaap	Derivative Assets Current DerivativeAssetsCurrent	304000	USD
CY2018Q4	us-gaap	Derivative Assets Current DerivativeAssetsCurrent	1500000	USD
CY2017Q4	us-gaap	Derivative Collateral Obligation To Return Cash DerivativeCollateralObligationToReturnCash	1282000	USD
CY2018Q4	us-gaap	Derivative Collateral Obligation To Return Cash DerivativeCollateralObligationToReturnCash	1408000	USD
CY2017Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	1586000	USD
CY2018Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	2927000	USD
CY2017Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	13756000	USD
CY2018Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	6801000	USD
CY2016	us-gaap	Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet	-953000	USD
CY2017	us-gaap	Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet	-75000	USD
CY2018	us-gaap	Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet	0	USD
CY2017Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	2259000	USD
CY2018Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	1007000	USD
CY2017Q4	us-gaap	Derivative Liabilities Current DerivativeLiabilitiesCurrent	2081000	USD
CY2018Q4	us-gaap	Derivative Liabilities Current DerivativeLiabilitiesCurrent	947000	USD
CY2017Q4	us-gaap	Derivative Liability Collateral Right To Reclaim Cash Offset DerivativeLiabilityCollateralRightToReclaimCashOffset	11497000	USD
CY2018Q4	us-gaap	Derivative Liability Collateral Right To Reclaim Cash Offset DerivativeLiabilityCollateralRightToReclaimCashOffset	5794000	USD
CY2016	us-gaap	Discontinued Operation Gain Loss From Disposal Of Discontinued Operation Before Income Tax DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax	0	USD
CY2017	us-gaap	Discontinued Operation Gain Loss From Disposal Of Discontinued Operation Before Income Tax DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax	0	USD
CY2018	us-gaap	Discontinued Operation Gain Loss From Disposal Of Discontinued Operation Before Income Tax DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax	-3259000	USD
CY2018	us-gaap	Discontinued Operation Gain Loss From Disposal Of Discontinued Operation Before Income Tax DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax	-3300000	USD
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CY2017Q4	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	-0.26
CY2017	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	-0.32
CY2018Q1	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	-0.05
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CY2018Q4	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	-0.02
CY2018	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	-0.13
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CY2017	us-gaap	Discontinued Operation Tax Effect Of Discontinued Operation DiscontinuedOperationTaxEffectOfDiscontinuedOperation	-8413000	USD
CY2018	us-gaap	Discontinued Operation Tax Effect Of Discontinued Operation DiscontinuedOperationTaxEffectOfDiscontinuedOperation	-2618000	USD
CY2017Q4	us-gaap	Disposal Group Including Discontinued Operation Deferred Tax Assets Noncurrent DisposalGroupIncludingDiscontinuedOperationDeferredTaxAssetsNoncurrent	16966000	USD
CY2016	us-gaap	Disposal Group Including Discontinued Operation Depreciation And Amortization DisposalGroupIncludingDiscontinuedOperationDepreciationAndAmortization	13510000	USD
CY2017	us-gaap	Disposal Group Including Discontinued Operation Depreciation And Amortization DisposalGroupIncludingDiscontinuedOperationDepreciationAndAmortization	7521000	USD
CY2018	us-gaap	Disposal Group Including Discontinued Operation Depreciation And Amortization DisposalGroupIncludingDiscontinuedOperationDepreciationAndAmortization	1300000	USD
CY2016	us-gaap	Disposal Group Including Discontinued Operation Operating Expense DisposalGroupIncludingDiscontinuedOperationOperatingExpense	27187000	USD
CY2017	us-gaap	Disposal Group Including Discontinued Operation Operating Expense DisposalGroupIncludingDiscontinuedOperationOperatingExpense	22872000	USD
CY2018	us-gaap	Disposal Group Including Discontinued Operation Operating Expense DisposalGroupIncludingDiscontinuedOperationOperatingExpense	11014000	USD
CY2016	us-gaap	Disposal Group Including Discontinued Operation Operating Income Loss DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss	-113596000	USD
CY2017	us-gaap	Disposal Group Including Discontinued Operation Operating Income Loss DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss	-25396000	USD
CY2018	us-gaap	Disposal Group Including Discontinued Operation Operating Income Loss DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss	-9676000	USD
CY2017Q4	us-gaap	Disposal Group Including Discontinued Operation Other Current Assets DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets	10360000	USD
CY2017Q4	us-gaap	Disposal Group Including Discontinued Operation Other Liabilities DisposalGroupIncludingDiscontinuedOperationOtherLiabilities	18966000	USD
CY2017Q4	us-gaap	Disposal Group Including Discontinued Operation Other Noncurrent Liabilities DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities	22808000	USD
CY2017Q4	us-gaap	Disposal Group Including Discontinued Operation Property Plant And Equipment DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipment	56916000	USD
CY2016	us-gaap	Disposal Group Including Discontinued Operation Revenue DisposalGroupIncludingDiscontinuedOperationRevenue	34058000	USD
CY2017	us-gaap	Disposal Group Including Discontinued Operation Revenue DisposalGroupIncludingDiscontinuedOperationRevenue	25382000	USD
CY2018	us-gaap	Disposal Group Including Discontinued Operation Revenue DisposalGroupIncludingDiscontinuedOperationRevenue	5897000	USD
CY2016	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	87570000	USD
CY2017	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	96744000	USD
CY2018	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	106591000	USD
CY2016	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.41
CY2017Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.44
CY2017Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.42
CY2017Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.52
CY2017Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.95
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.33
CY2018Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.49
CY2018Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.41
CY2018Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.32
CY2018Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.50
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	4.75
CY2016	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.37
CY2017Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.39
CY2017Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.40
CY2017Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.50
CY2017Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.92
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.21
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
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	4.66
CY2016	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.287
CY2017	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.260
CY2018	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	-0.093
CY2016	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2018	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2016	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0.000
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	-0.027
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0.016
CY2016	us-gaap	Effective Income Tax Rate Reconciliation Minority Interest Income Expense EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense	0.016
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Minority Interest Income Expense EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense	0.018
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Minority Interest Income Expense EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense	0.013
CY2016	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Depletion EffectiveIncomeTaxRateReconciliationNondeductibleExpenseDepletion	-0.008
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Depletion EffectiveIncomeTaxRateReconciliationNondeductibleExpenseDepletion	-0.006
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Depletion EffectiveIncomeTaxRateReconciliationNondeductibleExpenseDepletion	-0.004
CY2016	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Restructuring Charges EffectiveIncomeTaxRateReconciliationNondeductibleExpenseRestructuringCharges	0.005
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Restructuring Charges EffectiveIncomeTaxRateReconciliationNondeductibleExpenseRestructuringCharges	0.000
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Restructuring Charges EffectiveIncomeTaxRateReconciliationNondeductibleExpenseRestructuringCharges	0.000
CY2016	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.001
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.009
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.004
CY2016	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.012
CY2017	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.009
CY2018	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.023
CY2016	us-gaap	Effective Income Tax Rate Reconciliation Tax Contingencies EffectiveIncomeTaxRateReconciliationTaxContingencies	-0.027
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Tax Contingencies EffectiveIncomeTaxRateReconciliationTaxContingencies	-0.002
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Contingencies EffectiveIncomeTaxRateReconciliationTaxContingencies	0.000
CY2016	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.004
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.017
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.020
CY2017Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	52467000	USD
CY2018Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	63742000	USD
CY2018Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	12000000	USD
CY2018	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P1Y11M
CY2017Q4	us-gaap	Energy Related Inventory Natural Gas In Storage EnergyRelatedInventoryNaturalGasInStorage	40589000	USD
CY2018Q4	us-gaap	Energy Related Inventory Natural Gas In Storage EnergyRelatedInventoryNaturalGasInStorage	39368000	USD
CY2017Q4	us-gaap	Energy Related Inventory Other Fossil Fuel EnergyRelatedInventoryOtherFossilFuel	2962000	USD
CY2018Q4	us-gaap	Energy Related Inventory Other Fossil Fuel EnergyRelatedInventoryOtherFossilFuel	2850000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	800000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	800000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	800000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	800000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	800000	USD
CY2016	us-gaap	Gain Loss On Sale Of Derivatives GainLossOnSaleOfDerivatives	28820000	USD
CY2017	us-gaap	Gain Loss On Sale Of Derivatives GainLossOnSaleOfDerivatives	0	USD
CY2018	us-gaap	Gain Loss On Sale Of Derivatives GainLossOnSaleOfDerivatives	0	USD
CY2016Q4	us-gaap	Goodwill Goodwill	1299454000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	1299454000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	1299454000	USD
CY2017	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	0	USD
CY2018	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	0	USD
CY2018Q4	us-gaap	Guarantee Obligations Maximum Exposure GuaranteeObligationsMaximumExposure	94490000	USD
CY2016	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	137132000	USD
CY2017Q1	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	78092000	USD
CY2017Q2	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	22811000	USD
CY2017Q3	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	28963000	USD
CY2017Q4	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	64267000	USD
CY2017	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	194133000	USD
CY2018Q1	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	135347000	USD
CY2018Q2	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	24344000	USD
CY2018Q3	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	17807000	USD
CY2018Q4	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	87831000	USD
CY2018	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	265329000	USD
CY2016	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	205894000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	281742000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	255882000	USD
CY2016	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	146793000	USD
CY2017Q1	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	81715000	USD
CY2017Q2	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	25927000	USD
CY2017Q3	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	32898000	USD
CY2017Q4	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	67835000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	208375000	USD
CY2018Q1	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	138977000	USD
CY2018Q2	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	27167000	USD
CY2018Q3	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	21801000	USD
CY2018Q4	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	91604000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	279549000	USD
CY2016	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	2.64
CY2017Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	1.47
CY2017Q2	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.43
CY2017Q3	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.54
CY2017Q4	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	1.21
CY2017	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	3.65
CY2018Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	2.54
CY2018Q2	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.46
CY2018Q3	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.33
CY2018Q4	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	1.52
CY2018	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	4.88
CY2016	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	2.57
CY2017Q1	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	1.42
CY2017Q2	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.41
CY2017Q3	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.52
CY2017Q4	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	1.17
CY2017	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	3.52
CY2018Q1	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	2.50
CY2018Q2	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.45
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
CY2018	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	4.78
CY2016	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-64162000	USD
CY2017Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-1569000	USD
CY2017Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-616000	USD
CY2017Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-1300000	USD
CY2017Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-13614000	USD
CY2017	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-17099000	USD
CY2018Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-2343000	USD
CY2018Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-2427000	USD
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
CY2018	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-6887000	USD
CY2016	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-1.20
CY2017Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.03
CY2017Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.01
CY2017Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.02
CY2017Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.25
CY2017	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.31
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
CY2018	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.12
CY2016	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	59101000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	73367000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-23667000	USD
CY2017	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	8000000	USD
CY2018	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	4000000	USD
CY2016	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	1156000	USD
CY2017	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-1775000	USD
CY2018	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	14730000	USD
CY2017Q4	us-gaap	Income Taxes Receivable IncomeTaxesReceivable	0	USD
CY2018Q4	us-gaap	Income Taxes Receivable IncomeTaxesReceivable	12978000	USD
CY2016	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	27172000	USD
CY2017	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	-4534000	USD
CY2018	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	45966000	USD
CY2016	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-1211000	USD
CY2017	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	10089000	USD
CY2018	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	2919000	USD
CY2016	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	-33023000	USD
CY2017	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	-28222000	USD
CY2018	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	5305000	USD
CY2016	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	660000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	8418000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-6689000	USD
CY2016	us-gaap	Increase Decrease In Other Regulatory Assets IncreaseDecreaseInOtherRegulatoryAssets	-3614000	USD
CY2017	us-gaap	Increase Decrease In Other Regulatory Assets IncreaseDecreaseInOtherRegulatoryAssets	15407000	USD
CY2018	us-gaap	Increase Decrease In Other Regulatory Assets IncreaseDecreaseInOtherRegulatoryAssets	-33608000	USD
CY2016	us-gaap	Increase Decrease In Regulatory Liabilities IncreaseDecreaseInRegulatoryLiabilities	-14082000	USD
CY2017	us-gaap	Increase Decrease In Regulatory Liabilities IncreaseDecreaseInRegulatoryLiabilities	-4536000	USD
CY2018	us-gaap	Increase Decrease In Regulatory Liabilities IncreaseDecreaseInRegulatoryLiabilities	18533000	USD
CY2016	us-gaap	Incremental Common Shares Attributable To Equity Unit Purchase Agreements IncrementalCommonSharesAttributableToEquityUnitPurchaseAgreements	1222000	shares
CY2017	us-gaap	Incremental Common Shares Attributable To Equity Unit Purchase Agreements IncrementalCommonSharesAttributableToEquityUnitPurchaseAgreements	1783000	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Equity Unit Purchase Agreements IncrementalCommonSharesAttributableToEquityUnitPurchaseAgreements	898000	shares
CY2016	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	127000	shares
CY2017	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	116000	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	168000	shares
CY2015Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	3380000	USD
CY2016Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	8392000	USD
CY2017Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	7559000	USD
CY2018Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	14337000	USD
CY2016	us-gaap	Interest Costs Incurred InterestCostsIncurred	139091000	USD
CY2017	us-gaap	Interest Costs Incurred InterestCostsIncurred	140533000	USD
CY2018	us-gaap	Interest Costs Incurred InterestCostsIncurred	143720000	USD
CY2016	us-gaap	Interest Expense InterestExpense	136110000	USD
CY2017	us-gaap	Interest Expense InterestExpense	138118000	USD
CY2018	us-gaap	Interest Expense InterestExpense	141616000	USD
CY2016	us-gaap	Interest Paid Net InterestPaidNet	113627000	USD
CY2017	us-gaap	Interest Paid Net InterestPaidNet	132428000	USD
CY2018	us-gaap	Interest Paid Net InterestPaidNet	137965000	USD
CY2017Q4	us-gaap	Interest Payable Current InterestPayableCurrent	33822000	USD
CY2018Q4	us-gaap	Interest Payable Current InterestPayableCurrent	31759000	USD
CY2017Q4	us-gaap	Inventory Net InventoryNet	113283000	USD
CY2018Q4	us-gaap	Inventory Net InventoryNet	117299000	USD
CY2017Q4	us-gaap	Inventory Raw Materials And Supplies InventoryRawMaterialsAndSupplies	69732000	USD
CY2018Q4	us-gaap	Inventory Raw Materials And Supplies InventoryRawMaterialsAndSupplies	75081000	USD
CY2016	us-gaap	Investment Income Interest InvestmentIncomeInterest	1429000	USD
CY2017	us-gaap	Investment Income Interest InvestmentIncomeInterest	1016000	USD
CY2018	us-gaap	Investment Income Interest InvestmentIncomeInterest	1641000	USD
CY2016	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	9568000	USD
CY2017	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	10325000	USD
CY2018	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	2667000	USD
CY2017Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	6658902000	USD
CY2018Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	6963327000	USD
CY2017Q4	us-gaap	Liabilities Current LiabilitiesCurrent	649101000	USD
CY2018Q4	us-gaap	Liabilities Current LiabilitiesCurrent	648230000	USD
CY2017Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	1080195000	USD
CY2018Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	1076839000	USD
CY2017Q4	us-gaap	Liabilities Of Disposal Group Including Discontinued Operation Current LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent	41774000	USD
CY2018Q4	us-gaap	Liabilities Of Disposal Group Including Discontinued Operation Current LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent	0	USD
CY2015Q4	us-gaap	Liability For Uncertain Tax Positions Noncurrent LiabilityForUncertainTaxPositionsNoncurrent	31986000	USD
CY2016Q4	us-gaap	Liability For Uncertain Tax Positions Noncurrent LiabilityForUncertainTaxPositionsNoncurrent	3592000	USD
CY2017Q4	us-gaap	Liability For Uncertain Tax Positions Noncurrent LiabilityForUncertainTaxPositionsNoncurrent	3263000	USD
CY2018Q4	us-gaap	Liability For Uncertain Tax Positions Noncurrent LiabilityForUncertainTaxPositionsNoncurrent	3583000	USD
CY2017Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	5743000	USD
CY2018Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	5743000	USD
CY2018Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	1937855000	USD
CY2018Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	525000000	USD
CY2018Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	0	USD
CY2018Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	8435000	USD
CY2018Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	505743000	USD
CY2017Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	3109400000	USD
CY2018Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	2950835000	USD
CY2017Q4	us-gaap	Long Term Investments LongTermInvestments	13090000	USD
CY2018Q4	us-gaap	Long Term Investments LongTermInvestments	41013000	USD
CY2016	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	9561000	USD
CY2017	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	19392000	USD
CY2018	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	19617000	USD
CY2016	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	840998000	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-108695000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-17057000	USD
CY2016	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1588165000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-317118000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-465849000	USD
CY2016	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-1579752000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-324999000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-486234000	USD
CY2016	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	320479000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	428261000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	488811000	USD
CY2016	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	317735000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	409030000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	494327000	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	72970000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	177034000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	258442000	USD
CY2016	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	9661000	USD
CY2017Q1	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3623000	USD
CY2017Q2	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3116000	USD
CY2017Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3935000	USD
CY2017Q4	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3568000	USD
CY2017	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	14242000	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
CY2018	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	14220000	USD
CY2016	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	72970000	USD
CY2017Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	76523000	USD
CY2017Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	22195000	USD
CY2017Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	27663000	USD
CY2017Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	50653000	USD
CY2017	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	177034000	USD
CY2018Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	133004000	USD
CY2018Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	21917000	USD
CY2018Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	16950000	USD
CY2018Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	86571000	USD
CY2018	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	258442000	USD
CY2017Q4	us-gaap	Noncontrolling Interest In Variable Interest Entity NoncontrollingInterestInVariableInterestEntity	111232000	USD
CY2018Q4	us-gaap	Noncontrolling Interest In Variable Interest Entity NoncontrollingInterestInVariableInterestEntity	105835000	USD
CY2016	us-gaap	Noncontrolling Interest Increase From Sale Of Parent Equity Interest NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest	177233000	USD
CY2016	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	4394000	USD
CY2017	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	2108000	USD
CY2018	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	-1180000	USD
CY2016	us-gaap	Operating Expenses OperatingExpenses	1202735000	USD
CY2017	us-gaap	Operating Expenses OperatingExpenses	1263530000	USD
CY2018	us-gaap	Operating Expenses OperatingExpenses	1357231000	USD
CY2016	us-gaap	Operating Income Loss OperatingIncomeLoss	336181000	USD
CY2017Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	150186000	USD
CY2017Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	69796000	USD
CY2017Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	79559000	USD
CY2017Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	117195000	USD
CY2017	us-gaap	Operating Income Loss OperatingIncomeLoss	416736000	USD
CY2018Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	148274000	USD
CY2018Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	69551000	USD
CY2018Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	65085000	USD
CY2018Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	114127000	USD
CY2018	us-gaap	Operating Income Loss OperatingIncomeLoss	397037000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	1052000	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 In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	224000	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 Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	464000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	1776000	USD
CY2017Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	45172000	USD
CY2018Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	32431000	USD
CY2017Q4	us-gaap	Other Assets Current OtherAssetsCurrent	25367000	USD
CY2018Q4	us-gaap	Other Assets Current OtherAssetsCurrent	29982000	USD
CY2017Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	10149000	USD
CY2018Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	14352000	USD
CY2016	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Costs Credit Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostsCreditArisingDuringPeriodNetOfTax	247000	USD
CY2017	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Costs Credit Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostsCreditArisingDuringPeriodNetOfTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Costs Credit Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostsCreditArisingDuringPeriodNetOfTax	0	USD
CY2016	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	-1738000	USD
CY2017	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	-1890000	USD
CY2018	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	2155000	USD
CY2016	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	-757000	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
CY2016	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	-154000	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
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
CY2016	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	-67000	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
CY2016	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-25828000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	681000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	7027000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Benefit Plan Improvement Tax Effect OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBenefitPlanImprovementTaxEffect	107000	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
CY2016	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-600000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-585000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-586000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-1378000	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
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
CY2016	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	55307000	USD
CY2017	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	5813000	USD
CY2018	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	1841000	USD
CY2017Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	105735000	USD
CY2018Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	109377000	USD
CY2016	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	5519000	USD
CY2017	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	4773000	USD
CY2018	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-5836000	USD
CY2016	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	1124000	USD
CY2017	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-213000	USD
CY2018	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-1799000	USD
CY2016	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	562000	USD
CY2017Q1	us-gaap	Payments For Repurchase Of Redeemable Noncontrolling Interest PaymentsForRepurchaseOfRedeemableNoncontrollingInterest	5600000	USD
CY2017	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-1011000	USD
CY2018	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	4281000	USD
CY2016	us-gaap	Payments Of Dividends PaymentsOfDividends	87570000	USD
CY2017	us-gaap	Payments Of Dividends PaymentsOfDividends	96744000	USD
CY2018	us-gaap	Payments Of Dividends PaymentsOfDividends	106591000	USD
CY2016	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	0	USD
CY2017	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	0	USD
CY2018	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	24429000	USD
CY2016	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	454952000	USD
CY2017	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	326010000	USD
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	457524000	USD
CY2016	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	9561000	USD
CY2017	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	18397000	USD
CY2018	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	19617000	USD
CY2016	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	14291000	USD
CY2017	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	10141000	USD
CY2018	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	14068000	USD
CY2017Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	159646000	USD
CY2018Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	145147000	USD
CY2016	us-gaap	Pension Contributions PensionContributions	14200000	USD
CY2017	us-gaap	Pension Contributions PensionContributions	27700000	USD
CY2018	us-gaap	Pension Contributions PensionContributions	12700000	USD
CY2018Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	25000000	shares
CY2018Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2015Q4	us-gaap	Proceeds From Convertible Debt ProceedsFromConvertibleDebt	299000000	USD
CY2016	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	121619000	USD
CY2017	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	4408000	USD
CY2018	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	300834000	USD
CY2016Q1	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	546000000	USD
CY2016	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	1767608000	USD
CY2017	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	0	USD
CY2018	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	700000000	USD
CY2016Q2	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	216000000	USD
CY2016	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	216370000	USD
CY2017	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	USD
CY2018	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	USD
CY2016	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-22960000	USD
CY2017	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-6919000	USD
CY2018	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-11260000	USD
CY2016	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	19800000	USD
CY2017	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	114700000	USD
CY2018	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-25680000	USD
CY2016	us-gaap	Profit Loss ProfitLoss	82631000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	191276000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	272662000	USD
CY2017Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	5567518000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	6000015000	USD
CY2017	us-gaap	Property Plant And Equipment Gross Period Increase Decrease PropertyPlantAndEquipmentGrossPeriodIncreaseDecrease	337689000	USD
CY2018	us-gaap	Property Plant And Equipment Gross Period Increase Decrease PropertyPlantAndEquipmentGrossPeriodIncreaseDecrease	502424000	USD
CY2017Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	4541430000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	4854879000	USD
CY2016	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	3270000	USD
CY2017	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	2321000	USD
CY2018	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	619000	USD
CY2017Q4	us-gaap	Regulatory Assets RegulatoryAssets	297454000	USD
CY2018Q4	us-gaap	Regulatory Assets RegulatoryAssets	284235000	USD
CY2017Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	81016000	USD
CY2018Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	48776000	USD
CY2017Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	216438000	USD
CY2018Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	235459000	USD
CY2017Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	485126000	USD
CY2018Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	540794000	USD
CY2017Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	6832000	USD
CY2018Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	29810000	USD
CY2017Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	478294000	USD
CY2018Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	510984000	USD
CY2016	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	1164308000	USD
CY2017	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	105743000	USD
CY2018	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	854743000	USD
CY2017Q4	us-gaap	Restricted Cash And Investments Current RestrictedCashAndInvestmentsCurrent	2820000	USD
CY2018Q4	us-gaap	Restricted Cash And Investments Current RestrictedCashAndInvestmentsCurrent	3369000	USD
CY2017Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	548617000	USD
CY2018Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	700396000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1748542000	USD
CY2016	us-gaap	Revenues Revenues	1538916000	USD
CY2017Q1	us-gaap	Revenues Revenues	547528000	USD
CY2017Q2	us-gaap	Revenues Revenues	341829000	USD
CY2017Q3	us-gaap	Revenues Revenues	335611000	USD
CY2017Q4	us-gaap	Revenues Revenues	455298000	USD
CY2017	us-gaap	Revenues Revenues	1680266000	USD
CY2018Q1	us-gaap	Revenues Revenues	575389000	USD
CY2018Q2	us-gaap	Revenues Revenues	355704000	USD
CY2018Q3	us-gaap	Revenues Revenues	321979000	USD
CY2018Q4	us-gaap	Revenues Revenues	501196000	USD
CY2018	us-gaap	Revenues Revenues	1754268000	USD
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
CY2016	us-gaap	Share Based Compensation ShareBasedCompensation	10885000	USD
CY2017	us-gaap	Share Based Compensation ShareBasedCompensation	7626000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	12390000	USD
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	800180	shares
CY2017Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	211300000	USD
CY2018Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	185620000	USD
CY2016	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	2983000	USD
CY2017	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	3156000	USD
CY2018	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	220000	USD
CY2016	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	119990000	USD
CY2018	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	299000000	USD
CY2016	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	5479000	USD
CY2017	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	7567000	USD
CY2018	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	7190000	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	1708974000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	2181588000	USD
CY2015Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1465867000	USD
CY2016Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1730134000	USD
CY2017Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1820206000	USD
CY2018Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2287423000	USD
CY2016	us-gaap	Stockholders Equity Other StockholdersEquityOther	-476000	USD
CY2018	us-gaap	Stockholders Equity Other StockholdersEquityOther	-82000	USD
CY2018	us-gaap	Subsidiary Or Equity Method Investee Cumulative Percentage Ownership After All Transactions SubsidiaryOrEquityMethodInvesteeCumulativePercentageOwnershipAfterAllTransactions	1
CY2016	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	46160000	USD
CY2017	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	51578000	USD
CY2018	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	51746000	USD
CY2017Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	39064	shares
CY2018Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	44253	shares
CY2017Q4	us-gaap	Treasury Stock Value TreasuryStockValue	2306000	USD
CY2018Q4	us-gaap	Treasury Stock Value TreasuryStockValue	2510000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	19174000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	5713000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	417000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	11643000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	0	USD
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
CY2016	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	0	USD
CY2017	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	5026000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	486000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	2423000	USD
CY2017	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	358000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	251000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	100000	USD
CY2018	us-gaap	Unrecorded Unconditional Purchase Obligation Term UnrecordedUnconditionalPurchaseObligationTerm	P60D
CY2016	us-gaap	Valuation Allowances And Reserves Adjustments ValuationAllowancesAndReservesAdjustments	2158000	USD
CY2017	us-gaap	Valuation Allowances And Reserves Adjustments ValuationAllowancesAndReservesAdjustments	0	USD
CY2018	us-gaap	Valuation Allowances And Reserves Adjustments ValuationAllowancesAndReservesAdjustments	0	USD
CY2015Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	1741000	USD
CY2016Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	2392000	USD
CY2017Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	3081000	USD
CY2018Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	3209000	USD
CY2016	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	2704000	USD
CY2017	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	4926000	USD
CY2018	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	6859000	USD
CY2016	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	9126000	USD
CY2017	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	12499000	USD
CY2018	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	10823000	USD
CY2016	us-gaap	Valuation Allowances And Reserves Recoveries ValuationAllowancesAndReservesRecoveries	4915000	USD
CY2017	us-gaap	Valuation Allowances And Reserves Recoveries ValuationAllowancesAndReservesRecoveries	8262000	USD
CY2018	us-gaap	Valuation Allowances And Reserves Recoveries ValuationAllowancesAndReservesRecoveries	4092000	USD
CY2016Q2	us-gaap	Variable Interest Entity Ownership Percentage VariableInterestEntityOwnershipPercentage	0.499
CY2016	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	53271000	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	55120000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	55486000	shares
CY2016	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	51922000	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	53221000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	54420000	shares
CY2018	us-gaap	Use Of Estimates UseOfEstimates	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Use of Estimates and Basis of Presentation</font></div><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div><div style="line-height:120%;text-align:left;font-size:10pt;"><font 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.</font></div></div>

Files In Submission

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0001130464-19-000012.txt	Edgar Link	pending
0001130464-19-000012-xbrl.zip	Edgar Link	pending
bkh-20181231.xml	Edgar Link	completed
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$BKH
BLACK HILLS CORP /SD/ Stock $bkh

2017 Q4 Form 10-K Financial Statement

#000113046419000012 Filed on February 19, 2019

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BKH BLACK HILLS CORP /SD/ Stock $bkh

2017 Q4 Form 10-K Financial Statement

#000113046419000012 Filed on February 19, 2019

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BKH
BLACK HILLS CORP /SD/ Stock $bkh