$BKH
BLACK HILLS CORP /SD/ Stock $bkh

$bkh Overview Financials Valuation SEC Filings Company Website

2016 Q4 Form 10-K Financial Statement

#000113046418000014 Filed on February 26, 2018

Income Statement

Concept	2016 Q4	2016 Q3	2016 Q2
Revenue	$455.4M	$324.1M	$317.8M
YoY Change	43.09%	19.13%	16.73%
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	$34.90M	$48.93M	$47.31M
YoY Change	259.79%	29.54%	18.11%
% of Gross Profit
Operating Expenses	$260.8M	$275.4M	$290.1M
YoY Change	5.63%	0.45%	-6.74%
Operating Profit	$110.3M	$70.84M	$63.73M
YoY Change	55905.08%	-3565.95%	-263.99%
Interest Expense	-$36.10M	-$35.30M	-$32.60M
YoY Change	54.94%	66.51%	75.27%
% of Operating Profit	-32.72%	-49.83%	-51.16%
Other Income/Expense, Net	$700.0K	-$33.88M	-$47.00K
YoY Change	16.67%	-4123.87%	-111.9%
Pretax Income	$133.5M	$24.53M	$3.592M
YoY Change	-715.21%	-211.6%	-106.31%
Income Tax	$47.90M	$6.644M	$309.0K
% Of Pretax Income	35.88%	27.09%	8.6%
Net Earnings	$18.20M	$17.88M	$3.283M
YoY Change	-228.17%	-279.87%	-107.85%
Net Earnings / Revenue	4.0%	5.52%	1.03%
Basic Earnings Per Share	$0.34	$0.27	$0.01
Diluted Earnings Per Share	$0.33	$0.26	$0.01
COMMON SHARES
Basic Shares Outstanding	53.15M shares	52.18M shares	51.51M shares
Diluted Shares Outstanding		53.73M shares	52.99M shares

Balance Sheet

Concept	2016 Q4	2016 Q3	2016 Q2
SHORT-TERM ASSETS
Cash & Short-Term Investments	$13.50M	$63.00M	$116.8M
YoY Change	-96.94%	62.37%	33.94%
Cash & Equivalents	$13.52M	$31.81M	$61.86M
Short-Term Investments
Other Short-Term Assets	$23.93M	$30.03M	$30.65M
YoY Change	-66.66%	-45.77%	-40.27%
Inventory	$103.6M	$113.5M	$85.19M
Prepaid Expenses
Receivables	$259.3M	$154.6M	$150.2M
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$466.8M	$387.0M	$388.8M
YoY Change	-42.12%	-3.79%	-11.35%
LONG-TERM ASSETS
Property, Plant & Equipment	$4.386B	$4.465B	$4.390B
YoY Change	34.58%	36.77%	37.04%
Goodwill	$1.299B	$1.300B	$1.303B
YoY Change	261.2%	261.69%	268.84%
Intangibles	$8.392M	$8.944M	$9.164M
YoY Change	148.28%	160.0%	185.39%
Long-Term Investments	$12.60M	$12.40M	$12.40M
YoY Change	5.0%	2.48%	2.48%
Other Assets	$11.51M	$12.80M	$15.44M
YoY Change	55.89%	70.64%	-10.83%
Total Long-Term Assets	$1.567B	$1.557B	$1.549B
YoY Change	185.4%	181.57%	179.2%
TOTAL ASSETS
Total Short-Term Assets	$466.8M	$387.0M	$388.8M
Total Long-Term Assets	$1.567B	$1.557B	$1.549B
Total Assets	$6.542B	$6.421B	$6.340B
YoY Change	41.39%	51.73%	50.63%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$152.1M	$110.6M	$115.2M
YoY Change	69.42%	20.73%	47.66%
Accrued Expenses	$235.5M	$228.5M	$218.3M
YoY Change	1.5%	-0.59%	35.96%
Deferred Revenue
YoY Change
Short-Term Debt	$96.60M	$75.00M	$75.00M
YoY Change	25.78%	-36.39%	-29.08%
Long-Term Debt Due	$5.743M	$5.743M	$930.7M
YoY Change
Total Short-Term Liabilities	$527.9M	$449.7M	$1.413B
YoY Change	29.92%	0.22%	294.12%
LONG-TERM LIABILITIES
Long-Term Debt	$3.211B	$3.212B	$2.221B
YoY Change	73.23%	106.79%	42.73%
Other Long-Term Liabilities	$115.9M	$141.0M	$122.0M
YoY Change	-25.41%	3.33%	-21.11%
Total Long-Term Liabilities	$1.068B	$1.033B	$1.022B
YoY Change	18.59%	9.59%	3.9%
TOTAL LIABILITIES
Total Short-Term Liabilities	$527.9M	$449.7M	$1.413B
Total Long-Term Liabilities	$1.068B	$1.033B	$1.022B
Total Liabilities	$1.596B	$1.483B	$2.434B
YoY Change	22.11%	6.57%	81.45%
SHAREHOLDERS EQUITY
Retained Earnings	$457.9M	$462.1M	$469.9M
YoY Change	-3.09%	-8.47%	-11.83%
Common Stock	$53.40M	$53.13M	$52.30M
YoY Change	4.23%	18.35%	16.55%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$791.0K	$1.155M	$975.0K
YoY Change	-58.1%	-35.44%	-44.95%
Treasury Stock Shares	15.26K shares	18.90K shares	18.90K shares
Shareholders Equity	$1.615B	$1.605B	$1.562B
YoY Change
Total Liabilities & Shareholders Equity	$6.542B	$6.421B	$6.340B
YoY Change	41.39%	51.73%	50.63%

Cashflow Statement

Concept	2016 Q4	2016 Q3	2016 Q2
OPERATING ACTIVITIES
Net Income	$18.20M	$17.88M	$3.283M
YoY Change	-228.17%	-279.87%	-107.85%
Depreciation, Depletion And Amortization	$34.90M	$48.93M	$47.31M
YoY Change	259.79%	29.54%	18.11%
Cash From Operating Activities	$111.3M	-$13.60M	$89.70M
YoY Change	90.26%	-112.2%	-12.83%
INVESTING ACTIVITIES
Capital Expenditures	-$120.9M	-$134.2M	-$116.0M
YoY Change	-245.49%	-6.15%	30.34%
Acquisitions
YoY Change
Other Investing Activities	-$8.700M	-$200.0K	$7.700M
YoY Change	-95.71%	-96.92%	-2025.0%
Cash From Investing Activities	-$129.5M	-$134.5M	-$108.2M
YoY Change	8.19%	-10.09%	21.3%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	100.0K	78.70M	93.60M
YoY Change	-99.98%	-864.08%	826.73%
NET CHANGE
Cash From Operating Activities	111.3M	-13.60M	89.70M
Cash From Investing Activities	-129.5M	-134.5M	-108.2M
Cash From Financing Activities	100.0K	78.70M	93.60M
Net Change In Cash	-18.10M	-69.40M	75.10M
YoY Change	-104.37%	43.39%	215.55%
FREE CASH FLOW
Cash From Operating Activities	$111.3M	-$13.60M	$89.70M
Capital Expenditures	-$120.9M	-$134.2M	-$116.0M
Free Cash Flow	$232.2M	$120.6M	$205.7M
YoY Change	-1043.9%	-52.61%	7.19%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2016	bkh	Asset Retirement Obligation Liabilities Acquired AssetRetirementObligationLiabilitiesAcquired	22412000	USD
CY2017	bkh	Asset Retirement Obligation Liabilities Acquired AssetRetirementObligationLiabilitiesAcquired	0	USD
CY2016Q2	bkh	At The Market Equity Offering Program Authorized Aggregate Value AtTheMarketEquityOfferingProgramAuthorizedAggregateValue	200000000	USD
CY2017Q3	bkh	At The Market Equity Offering Program Authorized Aggregate Value AtTheMarketEquityOfferingProgramAuthorizedAggregateValue	300000000	USD
CY2017	bkh	Business Acquisition Pro Forma Combined Federaland Stateincome Tax Rate BusinessAcquisitionProFormaCombinedFederalandStateincomeTaxRate	0.37
CY2016Q1	bkh	Business Combination Acquisition Related Costs Net Of Tax BusinessCombinationAcquisitionRelatedCostsNetOfTax	15000000	USD
CY2016Q2	bkh	Business Combination Acquisition Related Costs Net Of Tax BusinessCombinationAcquisitionRelatedCostsNetOfTax	4100000	USD
CY2016Q3	bkh	Business Combination Acquisition Related Costs Net Of Tax BusinessCombinationAcquisitionRelatedCostsNetOfTax	4100000	USD
CY2016Q4	bkh	Business Combination Acquisition Related Costs Net Of Tax BusinessCombinationAcquisitionRelatedCostsNetOfTax	5500000	USD
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
CY2016Q1	bkh	Business Combination Consideration Transferred Netof Long Term Debtand Cash Acquired BusinessCombinationConsiderationTransferredNetofLongTermDebtandCashAcquired	-1124238000	USD
CY2015	bkh	Business Combination Consideration Transferred Netof Long Term Debtand Cash Acquired BusinessCombinationConsiderationTransferredNetofLongTermDebtandCashAcquired	21970000	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
CY2016Q1	bkh	Business Combination Consideration Transferred Netof Long Term Debtand Cash Acquired Before Working Capital Adjustment BusinessCombinationConsiderationTransferredNetofLongTermDebtandCashAcquiredBeforeWorkingCapitalAdjustment	1135000000	USD
CY2015	bkh	Capitalized Interest CapitalizedInterest	326000	USD
CY2016	bkh	Capitalized Interest CapitalizedInterest	356000	USD
CY2017	bkh	Capitalized Interest CapitalizedInterest	223000	USD
CY2015Q4	bkh	Corporate Units Ownership Interest Percentage In Subordinated Notes CorporateUnitsOwnershipInterestPercentageInSubordinatedNotes	0.05
CY2015Q4	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
CY2015	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	456887000	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
CY2016Q4	bkh	Gross Amounts Offset In Statement Of Financial Position Assets GrossAmountsOffsetInStatementOfFinancialPositionAssets	3262000	USD
CY2017Q4	bkh	Gross Amounts Offset In Statement Of Financial Position Assets GrossAmountsOffsetInStatementOfFinancialPositionAssets	1282000	USD
CY2016Q4	bkh	Gross Amounts Offset In Statement Of Financial Position Liabilities GrossAmountsOffsetInStatementOfFinancialPositionLiabilities	11144000	USD
CY2017Q4	bkh	Gross Amounts Offset In Statement Of Financial Position Liabilities GrossAmountsOffsetInStatementOfFinancialPositionLiabilities	11497000	USD
CY2015	bkh	Investment Tax Credit Amortization InvestmentTaxCreditAmortization	113000	USD
CY2016	bkh	Investment Tax Credit Amortization InvestmentTaxCreditAmortization	52000	USD
CY2017	bkh	Investment Tax Credit Amortization InvestmentTaxCreditAmortization	45000	USD
CY2016Q4	bkh	Long Term Debt Before The Deduction Of Deferred Financing Costs LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts	3238754000	USD
CY2017Q4	bkh	Long Term Debt Before The Deduction Of Deferred Financing Costs LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts	3133621000	USD
CY2015	bkh	Non Cash Revision To Capitalized Asset Retirement Costs NonCashRevisionToCapitalizedAssetRetirementCosts	-1498000	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
CY2015Q4	bkh	Debt Instrument Convertible Present Value Of Future Contract Adjustment Payments DebtInstrumentConvertiblePresentValueOfFutureContractAdjustmentPayments	12115000	USD
CY2015Q4	bkh	Debt Instrument Convertible Reference Price DebtInstrumentConvertibleReferencePrice	40.25
CY2016Q4	bkh	Deferred Tax Liability State DeferredTaxLiabilityState	50258000	USD
CY2017Q4	bkh	Deferred Tax Liability State DeferredTaxLiabilityState	58930000	USD
CY2017	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
CY2016Q4	bkh	Disposal Group Including Discontinued Operation Derivative Assets Currentand Noncurrent DisposalGroupIncludingDiscontinuedOperationDerivativeAssetsCurrentandNoncurrent	153000	USD
CY2017Q4	bkh	Disposal Group Including Discontinued Operation Derivative Assets Currentand Noncurrent DisposalGroupIncludingDiscontinuedOperationDerivativeAssetsCurrentandNoncurrent	0	USD
CY2015	bkh	Disposal Group Including Discontinued Operations Corporate Expenses DisposalGroupIncludingDiscontinuedOperationsCorporateExpenses	9980000	USD
CY2016	bkh	Disposal Group Including Discontinued Operations Corporate Expenses DisposalGroupIncludingDiscontinuedOperationsCorporateExpenses	10924000	USD
CY2017	bkh	Disposal Group Including Discontinued Operations Corporate Expenses DisposalGroupIncludingDiscontinuedOperationsCorporateExpenses	9577000	USD
CY2016Q4	bkh	Disposal Group Including Discontinued Operations Derivative Liabilities Currentand Noncurrent DisposalGroupIncludingDiscontinuedOperationsDerivativeLiabilitiesCurrentandNoncurrent	1586000	USD
CY2017Q4	bkh	Disposal Group Including Discontinued Operations Derivative Liabilities Currentand Noncurrent DisposalGroupIncludingDiscontinuedOperationsDerivativeLiabilitiesCurrentandNoncurrent	0	USD
CY2015	bkh	Disposal Group Including Discontinued Operations Impairmentof Equity Investments DisposalGroupIncludingDiscontinuedOperationsImpairmentofEquityInvestments	4405000	USD
CY2016	bkh	Disposal Group Including Discontinued Operations Impairmentof Equity Investments DisposalGroupIncludingDiscontinuedOperationsImpairmentofEquityInvestments	0	USD
CY2017	bkh	Disposal Group Including Discontinued Operations Impairmentof Equity Investments DisposalGroupIncludingDiscontinuedOperationsImpairmentofEquityInvestments	0	USD
CY2015	bkh	Disposal Group Including Discontinued Operations Impairmentof Longlived Assets DisposalGroupIncludingDiscontinuedOperationsImpairmentofLonglivedAssets	249608000	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
CY2015	bkh	Disposal Group Including Discontinued Operations Interest Income Expense Net DisposalGroupIncludingDiscontinuedOperationsInterestIncomeExpenseNet	931000	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
CY2015	bkh	Disposal Group Including Discontinued Operations Other Income Expensenet DisposalGroupIncludingDiscontinuedOperationsOtherIncomeExpensenet	-378000	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
CY2015	bkh	Disposal Group Including Discontinued Operations Total Operating Expenses DisposalGroupIncludingDiscontinuedOperationsTotalOperatingExpenses	313907000	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
CY2016Q2	bkh	Early Termination Settlement Of Gas Supply Contract EarlyTerminationSettlementOfGasSupplyContract	40000000	USD
CY2016Q2	bkh	Early Termination Settlement Of Gas Supply Contract Percentage Of Contract Committed To Distribution Customers EarlyTerminationSettlementOfGasSupplyContractPercentageOfContractCommittedToDistributionCustomers	0.75
CY2016Q2	bkh	Early Termination Settlement Of Gas Supply Contract Percentage Of Contract Not Subjectto Regulatory Recovery EarlyTerminationSettlementOfGasSupplyContractPercentageOfContractNotSubjecttoRegulatoryRecovery	0.25
CY2015	bkh	Effective Income Tax Rate Reconciliation Allowance For Other Funds Used During Construction Equity EffectiveIncomeTaxRateReconciliationAllowanceForOtherFundsUsedDuringConstructionEquity	-0.001
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
CY2015	bkh	Effective Income Tax Rate Reconciliation Flow Through Accounting EffectiveIncomeTaxRateReconciliationFlowThroughAccounting	-0.010
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
CY2015	bkh	Effective Income Tax Reconciliation Net Operating Loss Carryback EffectiveIncomeTaxReconciliationNetOperatingLossCarryback	0.000
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
CY2017	bkh	Electric Generation Capacity Megawatts ElectricGenerationCapacityMegawatts	200	MW
CY2015Q4	bkh	Equity Unit Annual Dividend Amount EquityUnitAnnualDividendAmount	2.125
CY2015Q4	bkh	Equity Unit Dividend Rate Percentage Annual EquityUnitDividendRatePercentageAnnual	0.0425
CY2015	bkh	Finite Lived Intangible Asset Purchase Accounting Adjustments FiniteLivedIntangibleAssetPurchaseAccountingAdjustments	434000	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
CY2017	bkh	Numberof Daysthe Companyhasto Pay Distributionsof Net Income Attributableto Noncontrolling Interests NumberofDaystheCompanyhastoPayDistributionsofNetIncomeAttributabletoNoncontrollingInterests	P30D
CY2017	bkh	Numberof Megawatts Capacity Sold NumberofMegawattsCapacitySold	40	MW
CY2015	bkh	Operating Expense Maintenance Operationsand Other Costsand Expense OperatingExpenseMaintenanceOperationsandOtherCostsandExpense	323809000	USD
CY2016	bkh	Operating Expense Maintenance Operationsand Other Costsand Expense OperatingExpenseMaintenanceOperationsandOtherCostsandExpense	426603000	USD
CY2017	bkh	Operating Expense Maintenance Operationsand Other Costsand Expense OperatingExpenseMaintenanceOperationsandOtherCostsandExpense	454605000	USD
CY2015Q4	bkh	Premiumon Publicly Traded Equity Units Known As Corporate Units PremiumonPubliclyTradedEquityUnitsKnownAsCorporateUnits	33000000	USD
CY2015	bkh	Premiumon Publicly Traded Equity Units Known As Corporate Units PremiumonPubliclyTradedEquityUnitsKnownAsCorporateUnits	33118000	USD
CY2015Q4	bkh	Proceeds From Issuance Of Common Stockand Sale Of Interest In Corporate Units ProceedsFromIssuanceOfCommonStockandSaleOfInterestInCorporateUnits	536000000	USD
CY2016	bkh	Property Plantand Equipment Including New Asset Acquisitions Gross Period Increase Decrease PropertyPlantandEquipmentIncludingNewAssetAcquisitionsGrossPeriodIncreaseDecrease	1591357000	USD
CY2017	bkh	Property Plantand Equipment Including New Asset Acquisitions Gross Period Increase Decrease PropertyPlantandEquipmentIncludingNewAssetAcquisitionsGrossPeriodIncreaseDecrease	360911000	USD
CY2015	bkh	Public Utilities Allowance For Funds Used During Construction Borrowed Interest Costs Capitalized PublicUtilitiesAllowanceForFundsUsedDuringConstructionBorrowedInterestCostsCapitalized	1250000	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
CY2017	bkh	Securities Excluded From Diluted Earnings Per Share Due To Net Loss SecuritiesExcludedFromDilutedEarningsPerShareDueToNetLoss	83000	shares
CY2017	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
CY2016	bkh	Total Capital Expenditures And Asset Acquisitions Of Continuing Operations TotalCapitalExpendituresAndAssetAcquisitionsOfContinuingOperations	1584688000	USD
CY2017	bkh	Total Capital Expenditures And Asset Acquisitions Of Continuing Operations TotalCapitalExpendituresAndAssetAcquisitionsOfContinuingOperations	337689000	USD
CY2015	bkh	Total Other Income Expense TotalOtherIncomeExpense	-80215000	USD
CY2016	bkh	Total Other Income Expense TotalOtherIncomeExpense	-130287000	USD
CY2017	bkh	Total Other Income Expense TotalOtherIncomeExpense	-134994000	USD
CY2017	dei	Amendment Flag AmendmentFlag	false
CY2017	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2017	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2017	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2017
CY2017	dei	Document Period End Date DocumentPeriodEndDate	2017-12-31
CY2017	dei	Document Type DocumentType	10-K
CY2017	dei	Entity Central Index Key EntityCentralIndexKey	0001130464
CY2018Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	53544761	shares
CY2017	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2017	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2017Q2	dei	Entity Public Float EntityPublicFloat	3563087139	USD
CY2017	dei	Entity Registrant Name EntityRegistrantName	BLACK HILLS CORP /SD/
CY2017	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2017	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2016Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	152129000	USD
CY2017Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	160887000	USD
CY2016Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	259311000	USD
CY2017Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	248330000	USD
CY2016Q4	us-gaap	Accrual For Taxes Other Than Income Taxes Current AccrualForTaxesOtherThanIncomeTaxesCurrent	37379000	USD
CY2017Q4	us-gaap	Accrual For Taxes Other Than Income Taxes Current AccrualForTaxesOtherThanIncomeTaxesCurrent	42029000	USD
CY2016Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	12552000	USD
CY2017Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	1022000	USD
CY2016Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	235548000	USD
CY2017Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	219462000	USD
CY2016Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	929119000	USD
CY2017Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1026088000	USD
CY2015Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-9055000	USD
CY2016Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-34883000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-41202000	USD
CY2016Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	1138982000	USD
CY2017Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	1150285000	USD
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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
CY2016Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	2379000	USD
CY2017Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	3081000	USD
CY2015	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	5617000	USD
CY2016	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	3861000	USD
CY2017	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	3349000	USD
CY2015	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	6364000	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
CY2015	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	230000	USD
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CY2017	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	833000	USD
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CY2016	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	3000	shares
CY2017	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	11000	shares
CY2015Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	23231000	USD
CY2016Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	46876000	USD
CY2017Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	52024000	USD
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CY2017	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	2061000	USD
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CY2017	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	0	USD
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CY2017	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	111000	USD
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CY2017Q4	us-gaap	Assets Assets	6658902000	USD
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CY2017Q4	us-gaap	Assets Current AssetsCurrent	570782000	USD
CY2016Q4	us-gaap	Assets Noncurrent Other Than Noncurrent Investments And Property Plant And Equipment AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment	1676221000	USD
CY2017Q4	us-gaap	Assets Noncurrent Other Than Noncurrent Investments And Property Plant And Equipment AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment	1533600000	USD
CY2016Q4	us-gaap	Assets Of Disposal Group Including Discontinued Operation AssetsOfDisposalGroupIncludingDiscontinuedOperation	86472000	USD
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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
CY2016Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	13518000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	15420000	USD
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CY2016Q4	us-gaap	Cash And Cash Equivalents At Carrying Value Including Discontinued Operations CashAndCashEquivalentsAtCarryingValueIncludingDiscontinuedOperations	13518000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value Including Discontinued Operations CashAndCashEquivalentsAtCarryingValueIncludingDiscontinuedOperations	15420000	USD
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CY2017	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	1902000	USD
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CY2016Q4	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.420
CY2016	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.68
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CY2017Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	1
CY2016Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	100000000	shares
CY2017Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	100000000	shares
CY2016Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	53397467	shares
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CY2016Q4	us-gaap	Common Stock Value CommonStockValue	53397000	USD
CY2017Q4	us-gaap	Common Stock Value CommonStockValue	53580000	USD
CY2015	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-26122000	USD
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CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	177715000	USD
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CY2015	us-gaap	Costs And Expenses CostsAndExpenses	377482000	USD
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CY2015	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	2624000	USD
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CY2016Q4	us-gaap	Customer Advances For Construction CustomerAdvancesForConstruction	1575000	USD
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CY2015	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	71332000	USD
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CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	80992000	USD
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CY2016Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	561935000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	336520000	USD
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CY2017Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	510774000	USD
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CY2017Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	26245000	USD
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CY2017	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Decrease On Service And Interest Cost Components1 DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnServiceAndInterestCostComponents1	126000	USD
CY2017	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Increase On Accumulated Postretirement Benefit Obligation DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnAccumulatedPostretirementBenefitObligation	2968000	USD
CY2017	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Increase On Service And Interest Cost Components DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnServiceAndInterestCostComponents	148000	USD
CY2017Q4	us-gaap	Defined Benefit Plan Expected Future Employer Contributions Next Fiscal Year DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear	13000000	USD
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CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	188246000	USD
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CY2017Q4	us-gaap	Derivative Assets DerivativeAssets	304000	USD
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CY2017Q4	us-gaap	Derivative Assets Current DerivativeAssetsCurrent	304000	USD
CY2016Q4	us-gaap	Derivative Assets Noncurrent DerivativeAssetsNoncurrent	222000	USD
CY2017Q4	us-gaap	Derivative Assets Noncurrent DerivativeAssetsNoncurrent	0	USD
CY2016Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	7469000	USD
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CY2017Q4	us-gaap	Disposal Group Including Discontinued Operation Other Liabilities DisposalGroupIncludingDiscontinuedOperationOtherLiabilities	18966000	USD
CY2016Q4	us-gaap	Disposal Group Including Discontinued Operation Other Noncurrent Liabilities DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities	22803000	USD
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CY2016Q4	us-gaap	Disposal Group Including Discontinued Operation Property Plant And Equipment DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipment	82812000	USD
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CY2015	us-gaap	Disposal Group Including Discontinued Operation Revenue DisposalGroupIncludingDiscontinuedOperationRevenue	43283000	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
CY2015	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	72604000	USD
CY2016	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	87570000	USD
CY2017	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	96744000	USD
CY2015	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.71
CY2016Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.78
CY2016Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.01
CY2016Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.27
CY2016Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.34
CY2016	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.41
CY2017Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	52467000	USD
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
CY2015	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.71
CY2016Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.77
CY2016Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.01
CY2016Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.26
CY2016Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.33
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
CY2015	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.357
CY2016	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.287
CY2017	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.260
CY2015	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.350
CY2016	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.350
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.350
CY2015	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0.000
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
CY2015	us-gaap	Effective Income Tax Rate Reconciliation Minority Interest Income Expense EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense	0.000
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
CY2015	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Depletion EffectiveIncomeTaxRateReconciliationNondeductibleExpenseDepletion	-0.007
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
CY2015	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Restructuring Charges EffectiveIncomeTaxRateReconciliationNondeductibleExpenseRestructuringCharges	0.000
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
CY2015	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.003
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
CY2015	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.015
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
CY2015	us-gaap	Effective Income Tax Rate Reconciliation Tax Contingencies EffectiveIncomeTaxRateReconciliationTaxContingencies	0.008
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
CY2015	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.001
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
CY2016Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	54553000	USD
CY2017Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	12000000	USD
CY2017	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P1Y11M
CY2016Q4	us-gaap	Energy Related Inventory Natural Gas In Storage EnergyRelatedInventoryNaturalGasInStorage	35087000	USD
CY2017Q4	us-gaap	Energy Related Inventory Natural Gas In Storage EnergyRelatedInventoryNaturalGasInStorage	40589000	USD
CY2016Q4	us-gaap	Energy Related Inventory Other Fossil Fuel EnergyRelatedInventoryOtherFossilFuel	3667000	USD
CY2017Q4	us-gaap	Energy Related Inventory Other Fossil Fuel EnergyRelatedInventoryOtherFossilFuel	2962000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	800000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	800000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	800000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	800000	USD
CY2017Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	800000	USD
CY2015	us-gaap	Gain Loss On Sale Of Derivatives GainLossOnSaleOfDerivatives	0	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
CY2015Q4	us-gaap	Goodwill Goodwill	359759000	USD
CY2016Q4	us-gaap	Goodwill Goodwill	1299454000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	1299454000	USD
CY2016	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	939695000	USD
CY2017	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	0	USD
CY2017Q4	us-gaap	Guarantee Obligations Maximum Exposure GuaranteeObligationsMaximumExposure	58221000	USD
CY2015	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	141548000	USD
CY2016Q1	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	45272000	USD
CY2016Q2	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	18514000	USD
CY2016Q3	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	21211000	USD
CY2016Q4	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	52135000	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
CY2015	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	220205000	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
CY2015	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	141548000	USD
CY2016Q1	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	45320000	USD
CY2016Q2	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	21128000	USD
CY2016Q3	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	24964000	USD
CY2016Q4	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	55381000	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
CY2015	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	3.12
CY2016Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.88
CY2016Q2	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.36
CY2016Q3	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.41
CY2016Q4	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.98
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
CY2015	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	3.12
CY2016Q1	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.87
CY2016Q2	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.35
CY2016Q3	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.39
CY2016Q4	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.96
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
CY2015	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-173659000	USD
CY2016Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-5270000	USD
CY2016Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-17845000	USD
CY2016Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-7080000	USD
CY2016Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-33967000	USD
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
CY2015	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-3.83
CY2016Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.10
CY2016Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.34
CY2016Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.13
CY2016Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.63
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
CY2015	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	78657000	USD
CY2016	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	59101000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	73367000	USD
CY2015	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	1202000	USD
CY2016	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	1156000	USD
CY2017	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-1775000	USD
CY2015	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	-33255000	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
CY2015	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-7216000	USD
CY2016	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-1211000	USD
CY2017	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	10089000	USD
CY2015	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	-74748000	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
CY2015	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	9033000	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
CY2015	us-gaap	Increase Decrease In Other Regulatory Assets IncreaseDecreaseInOtherRegulatoryAssets	-21883000	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
CY2015	us-gaap	Increase Decrease In Regulatory Liabilities IncreaseDecreaseInRegulatoryLiabilities	1675000	USD
CY2016	us-gaap	Increase Decrease In Regulatory Liabilities IncreaseDecreaseInRegulatoryLiabilities	-14082000	USD
CY2017	us-gaap	Increase Decrease In Regulatory Liabilities IncreaseDecreaseInRegulatoryLiabilities	-4536000	USD
CY2015	us-gaap	Incremental Common Shares Attributable To Equity Unit Purchase Agreements IncrementalCommonSharesAttributableToEquityUnitPurchaseAgreements	0	shares
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
CY2015	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	0	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
CY2014Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	3176000	USD
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
CY2015	us-gaap	Interest Costs Incurred InterestCostsIncurred	86226000	USD
CY2016	us-gaap	Interest Costs Incurred InterestCostsIncurred	139447000	USD
CY2017	us-gaap	Interest Costs Incurred InterestCostsIncurred	140756000	USD
CY2015	us-gaap	Interest Expense InterestExpense	84650000	USD
CY2016	us-gaap	Interest Expense InterestExpense	136110000	USD
CY2017	us-gaap	Interest Expense InterestExpense	138118000	USD
CY2015	us-gaap	Interest Paid Net InterestPaidNet	78744000	USD
CY2016	us-gaap	Interest Paid Net InterestPaidNet	113627000	USD
CY2017	us-gaap	Interest Paid Net InterestPaidNet	132428000	USD
CY2016Q4	us-gaap	Interest Payable Current InterestPayableCurrent	33982000	USD
CY2017Q4	us-gaap	Interest Payable Current InterestPayableCurrent	33822000	USD
CY2016Q4	us-gaap	Inventory Net InventoryNet	103606000	USD
CY2017Q4	us-gaap	Inventory Net InventoryNet	113283000	USD
CY2016Q4	us-gaap	Inventory Raw Materials And Supplies InventoryRawMaterialsAndSupplies	64852000	USD
CY2017Q4	us-gaap	Inventory Raw Materials And Supplies InventoryRawMaterialsAndSupplies	69732000	USD
CY2015	us-gaap	Investment Income Interest InvestmentIncomeInterest	1621000	USD
CY2016	us-gaap	Investment Income Interest InvestmentIncomeInterest	1429000	USD
CY2017	us-gaap	Investment Income Interest InvestmentIncomeInterest	1016000	USD
CY2015	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	7177000	USD
CY2016	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	9568000	USD
CY2017	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	10325000	USD
CY2016Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	6541773000	USD
CY2017Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	6658902000	USD
CY2016Q4	us-gaap	Liabilities Current LiabilitiesCurrent	527932000	USD
CY2017Q4	us-gaap	Liabilities Current LiabilitiesCurrent	649101000	USD
CY2016Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	1068223000	USD
CY2017Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	1080195000	USD
CY2016Q4	us-gaap	Liabilities Of Disposal Group Including Discontinued Operation Current LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent	11189000	USD
CY2017Q4	us-gaap	Liabilities Of Disposal Group Including Discontinued Operation Current LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent	41774000	USD
CY2016Q4	us-gaap	Liabilities Of Disposal Group Including Discontinued Operation Noncurrent LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent	23034000	USD
CY2017Q4	us-gaap	Liabilities Of Disposal Group Including Discontinued Operation Noncurrent LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent	0	USD
CY2014Q4	us-gaap	Liability For Uncertain Tax Positions Noncurrent LiabilityForUncertainTaxPositionsNoncurrent	32192000	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
CY2016Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	5743000	USD
CY2017Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	5743000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	2361855000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	0	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	8436000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	205743000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	555742000	USD
CY2016Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	3211189000	USD
CY2017Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	3109400000	USD
CY2016Q4	us-gaap	Long Term Investments LongTermInvestments	12561000	USD
CY2017Q4	us-gaap	Long Term Investments LongTermInvestments	13090000	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
CY2017Q1	us-gaap	Minority Interest Ownership Percentage By Noncontrolling Owners MinorityInterestOwnershipPercentageByNoncontrollingOwners	0.005
CY2015	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	483702000	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
CY2015	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-476389000	USD
CY2016	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1588742000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-317664000	USD
CY2015	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-288789000	USD
CY2016	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-1580329000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-325545000	USD
CY2015	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	424383000	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
CY2015	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	339017000	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
CY2015	us-gaap	Net Income Loss NetIncomeLoss	-32111000	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	72970000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	177034000	USD
CY2015	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	0	USD
CY2016Q1	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	48000	USD
CY2016Q2	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	2614000	USD
CY2016Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3753000	USD
CY2016Q4	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3246000	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
CY2015	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-32111000	USD
CY2016Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	40002000	USD
CY2016Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	669000	USD
CY2016Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	14131000	USD
CY2016Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	18168000	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
CY2016Q4	us-gaap	Noncontrolling Interest In Variable Interest Entity NoncontrollingInterestInVariableInterestEntity	115495000	USD
CY2017Q4	us-gaap	Noncontrolling Interest In Variable Interest Entity NoncontrollingInterestInVariableInterestEntity	111232000	USD
CY2016	us-gaap	Noncontrolling Interest Increase From Sale Of Parent Equity Interest NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest	177233000	USD
CY2015	us-gaap	Operating Expenses OperatingExpenses	960902000	USD
CY2016	us-gaap	Operating Expenses OperatingExpenses	1202735000	USD
CY2017	us-gaap	Operating Expenses OperatingExpenses	1263530000	USD
CY2015	us-gaap	Operating Income Loss OperatingIncomeLoss	300420000	USD
CY2016Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	91281000	USD
CY2016Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	63725000	USD
CY2016Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	70844000	USD
CY2016Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	110330000	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
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	5030000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	808000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	918000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	1957000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	3840000	USD
CY2017Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	3085000	USD
CY2016Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	52868000	USD
CY2017Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	45172000	USD
CY2016Q4	us-gaap	Other Assets Current OtherAssetsCurrent	23928000	USD
CY2017Q4	us-gaap	Other Assets Current OtherAssetsCurrent	25367000	USD
CY2016Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	11508000	USD
CY2017Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	10149000	USD
CY2015	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 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
CY2015	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	2657000	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
CY2015	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	1375000	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
CY2015	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	-150000	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
CY2015	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	-88000	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
CY2015	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	5989000	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
CY2015	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 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
CY2015	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-972000	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
CY2015	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-1850000	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
CY2015	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	13613000	USD
CY2016	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	55307000	USD
CY2017	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	5813000	USD
CY2016Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	115883000	USD
CY2017Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	105735000	USD
CY2015	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	4872000	USD
CY2016	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	5519000	USD
CY2017	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	4773000	USD
CY2015	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	158000	USD
CY2016	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	626000	USD
CY2017	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	1559000	USD
CY2015	us-gaap	Other Nonoperating Income OtherNonoperatingIncome	2075000	USD
CY2016	us-gaap	Other Nonoperating Income OtherNonoperatingIncome	1750000	USD
CY2017	us-gaap	Other Nonoperating Income OtherNonoperatingIncome	1346000	USD
CY2015	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	2814000	USD
CY2016	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	4394000	USD
CY2017	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	2108000	USD
CY2015	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	444000	USD
CY2016	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	1139000	USD
CY2017	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-465000	USD
CY2017Q1	us-gaap	Payments For Repurchase Of Redeemable Noncontrolling Interest PaymentsForRepurchaseOfRedeemableNoncontrollingInterest	5600000	USD
CY2015	us-gaap	Payments Of Dividends PaymentsOfDividends	72604000	USD
CY2016	us-gaap	Payments Of Dividends PaymentsOfDividends	87570000	USD
CY2017	us-gaap	Payments Of Dividends PaymentsOfDividends	96744000	USD
CY2015	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	266375000	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
CY2015	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	0	USD
CY2016	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	9561000	USD
CY2017	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	18397000	USD
CY2015	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	20616000	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
CY2016Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	173682000	USD
CY2017Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	159646000	USD
CY2015	us-gaap	Pension Contributions PensionContributions	10200000	USD
CY2016	us-gaap	Pension Contributions PensionContributions	14200000	USD
CY2017	us-gaap	Pension Contributions PensionContributions	27700000	USD
CY2017Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	25000000	shares
CY2017Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2015Q4	us-gaap	Proceeds From Convertible Debt ProceedsFromConvertibleDebt	299000000	USD
CY2015	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	248759000	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
CY2016Q1	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	546000000	USD
CY2015	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	300000000	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
CY2016Q2	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	216000000	USD
CY2015	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	USD
CY2016	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	216370000	USD
CY2017	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	USD
CY2015	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-9283000	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
CY2015	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	1800000	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
CY2015Q4	us-gaap	Proceeds From Sale Of Interest In Corporate Unit ProceedsFromSaleOfInterestInCorporateUnit	290030000	USD
CY2015	us-gaap	Proceeds From Sale Of Interest In Corporate Unit ProceedsFromSaleOfInterestInCorporateUnit	290030000	USD
CY2016	us-gaap	Proceeds From Sale Of Interest In Corporate Unit ProceedsFromSaleOfInterestInCorporateUnit	0	USD
CY2017	us-gaap	Proceeds From Sale Of Interest In Corporate Unit ProceedsFromSaleOfInterestInCorporateUnit	0	USD
CY2015	us-gaap	Profit Loss ProfitLoss	-32111000	USD
CY2016	us-gaap	Profit Loss ProfitLoss	82631000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	191276000	USD
CY2016Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	5315296000	USD
CY2017Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	5567518000	USD
CY2016	us-gaap	Property Plant And Equipment Gross Period Increase Decrease PropertyPlantAndEquipmentGrossPeriodIncreaseDecrease	460450000	USD
CY2017	us-gaap	Property Plant And Equipment Gross Period Increase Decrease PropertyPlantAndEquipmentGrossPeriodIncreaseDecrease	337689000	USD
CY2016Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	4386177000	USD
CY2017Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	4541430000	USD
CY2015	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	897000	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
CY2016Q4	us-gaap	Redeemable Noncontrolling Interest Equity Other Carrying Amount RedeemableNoncontrollingInterestEquityOtherCarryingAmount	4295000	USD
CY2017Q4	us-gaap	Redeemable Noncontrolling Interest Equity Other Carrying Amount RedeemableNoncontrollingInterestEquityOtherCarryingAmount	0	USD
CY2016Q4	us-gaap	Regulatory Assets RegulatoryAssets	296142000	USD
CY2017Q4	us-gaap	Regulatory Assets RegulatoryAssets	297454000	USD
CY2016Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	49260000	USD
CY2017Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	81016000	USD
CY2016Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	246882000	USD
CY2017Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	216438000	USD
CY2016Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	206756000	USD
CY2017Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	485126000	USD
CY2016Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	13067000	USD
CY2017Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	6832000	USD
CY2016Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	193689000	USD
CY2017Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	478294000	USD
CY2015	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	275000000	USD
CY2016	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	1164308000	USD
CY2017	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	105743000	USD
CY2016Q4	us-gaap	Restricted Cash And Investments Current RestrictedCashAndInvestmentsCurrent	2274000	USD
CY2017Q4	us-gaap	Restricted Cash And Investments Current RestrictedCashAndInvestmentsCurrent	2820000	USD
CY2016Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	457934000	USD
CY2017Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	548617000	USD
CY2015	us-gaap	Sales Revenue Net SalesRevenueNet	1261322000	USD
CY2016Q1	us-gaap	Sales Revenue Net SalesRevenueNet	441584000	USD
CY2016Q2	us-gaap	Sales Revenue Net SalesRevenueNet	317795000	USD
CY2016Q3	us-gaap	Sales Revenue Net SalesRevenueNet	324147000	USD
CY2016Q4	us-gaap	Sales Revenue Net SalesRevenueNet	455390000	USD
CY2016	us-gaap	Sales Revenue Net SalesRevenueNet	1538916000	USD
CY2017Q1	us-gaap	Sales Revenue Net SalesRevenueNet	547528000	USD
CY2017Q2	us-gaap	Sales Revenue Net SalesRevenueNet	341829000	USD
CY2017Q3	us-gaap	Sales Revenue Net SalesRevenueNet	335611000	USD
CY2017Q4	us-gaap	Sales Revenue Net SalesRevenueNet	455298000	USD
CY2017	us-gaap	Sales Revenue Net SalesRevenueNet	1680266000	USD
CY2015	us-gaap	Share Based Compensation ShareBasedCompensation	4076000	USD
CY2016	us-gaap	Share Based Compensation ShareBasedCompensation	10885000	USD
CY2017	us-gaap	Share Based Compensation ShareBasedCompensation	7626000	USD
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	979464	shares
CY2016Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	96600000	USD
CY2017Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	211300000	USD
CY2015	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	2957000	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
CY2015	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	254581000	USD
CY2016	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	119990000	USD
CY2015	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	4240000	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
CY2016Q4	us-gaap	Stockholders Equity StockholdersEquity	1614639000	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	1708974000	USD
CY2014Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1353884000	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
CY2015	us-gaap	Stockholders Equity Other StockholdersEquityOther	25000	USD
CY2016	us-gaap	Stockholders Equity Other StockholdersEquityOther	-476000	USD
CY2016	us-gaap	Subsidiary Or Equity Method Investee Cumulative Percentage Ownership After All Transactions SubsidiaryOrEquityMethodInvesteeCumulativePercentageOwnershipAfterAllTransactions	1
CY2015	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	40060000	USD
CY2016	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	46160000	USD
CY2017	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	51578000	USD
CY2016Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	15258	shares
CY2017Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	39064	shares
CY2016Q4	us-gaap	Treasury Stock Value TreasuryStockValue	791000	USD
CY2017Q4	us-gaap	Treasury Stock Value TreasuryStockValue	2306000	USD
CY2015	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	3491000	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
CY2015	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0	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
CY2016Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	0	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	0	USD
CY2015	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	1600000	USD
CY2016	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	0	USD
CY2017	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	0	USD
CY2015	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	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
CY2015	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	3285000	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
CY2017Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	200000	USD
CY2015	us-gaap	Valuation Allowances And Reserves Adjustments ValuationAllowancesAndReservesAdjustments	0	USD
CY2016	us-gaap	Valuation Allowances And Reserves Adjustments ValuationAllowancesAndReservesAdjustments	2158000	USD
CY2017	us-gaap	Valuation Allowances And Reserves Adjustments ValuationAllowancesAndReservesAdjustments	0	USD
CY2014Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	1516000	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
CY2015	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	3860000	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
CY2015	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	7767000	USD
CY2016	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	9126000	USD
CY2017	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	12499000	USD
CY2015	us-gaap	Valuation Allowances And Reserves Recoveries ValuationAllowancesAndReservesRecoveries	4132000	USD
CY2016	us-gaap	Valuation Allowances And Reserves Recoveries ValuationAllowancesAndReservesRecoveries	4915000	USD
CY2017	us-gaap	Valuation Allowances And Reserves Recoveries ValuationAllowancesAndReservesRecoveries	8262000	USD
CY2016Q2	us-gaap	Variable Interest Entity Ownership Percentage VariableInterestEntityOwnershipPercentage	0.499
CY2015	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	45288000	shares
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
CY2015	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	45288000	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
CY2017	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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bkh-20171231.xml	Edgar Link	completed
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$BKH
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2016 Q4 Form 10-K Financial Statement

#000113046418000014 Filed on February 26, 2018

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BKH BLACK HILLS CORP /SD/ Stock $bkh

2016 Q4 Form 10-K Financial Statement

#000113046418000014 Filed on February 26, 2018

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BKH
BLACK HILLS CORP /SD/ Stock $bkh