$AVA
AVISTA CORP Stock $ava

$ava Overview Financials Valuation SEC Filings Company Website

2016 Form 10-K Financial Statement

#000010491817000053 Filed on February 22, 2017

Income Statement

Concept	2016	2015 Q4	2015 Q3
Revenue	$1.442B	$387.3M	$313.6M
YoY Change	-2.85%	-5.96%	4.01%
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	$164.9M	$38.30M	$37.40M
YoY Change	11.56%	8.19%	8.72%
% of Gross Profit
Operating Expenses	$1.143B	$316.9M	$277.7M
YoY Change	-7.23%	-8.17%	3.31%
Operating Profit	$299.9M	$70.37M	$35.91M
YoY Change	18.42%	5.41%	9.61%
Interest Expense	$86.50M	-$19.80M	$19.95M
YoY Change	8.16%	11.86%	7.02%
% of Operating Profit	28.85%	-28.14%	55.56%
Other Income/Expense, Net	$20.00K	$3.400M	$2.123M
YoY Change	-99.78%	30.77%	-18.6%
Pretax Income	$215.4M	$53.90M	$18.87M
YoY Change	16.05%	4.46%	5.85%
Income Tax	$78.09M	$20.10M	$6.115M
% Of Pretax Income	36.25%	37.29%	32.41%
Net Earnings	$137.2M	$38.52M	$13.01M
YoY Change	11.36%	19.56%	24.5%
Net Earnings / Revenue	9.51%	9.95%	4.15%
Basic Earnings Per Share	$2.16		$0.21
Diluted Earnings Per Share	$2.15	$0.61	$0.21
COMMON SHARES
Basic Shares Outstanding	63.51M shares	62.31M shares	62.30M shares
Diluted Shares Outstanding	63.92M shares	62.76M shares	62.69M shares

Balance Sheet

Concept	2016	2015 Q4	2015 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments	$9.000M	$10.00M	$9.000M
YoY Change	-10.0%	-54.55%	-10.0%
Cash & Equivalents	$9.000M	$10.48M	$9.314M
Short-Term Investments
Other Short-Term Assets	$61.00M	$30.62M	$39.08M
YoY Change	27.08%	-32.06%	1.46%
Inventory	$53.00M	$54.15M	$59.74M
Prepaid Expenses
Receivables	$180.0M	$169.0M	$111.0M
Other Receivables	$49.00M	$25.00M	$0.00
Total Short-Term Assets	$351.0M	$306.0M	$258.0M
YoY Change	14.71%	-22.59%	-2.72%
LONG-TERM ASSETS
Property, Plant & Equipment	$4.147B	$3.899B	$3.784B
YoY Change	6.36%	7.71%	6.95%
Goodwill		$57.67M	$57.67M
YoY Change		-0.52%	10.01%
Intangibles
YoY Change
Long-Term Investments	$84.00M	$71.00M	$65.00M
YoY Change	18.31%	9.23%	1.56%
Other Assets	$669.0M	$143.6M	$140.6M
YoY Change	19.89%	-4.98%	-7.64%
Total Long-Term Assets	$4.959B	$4.601B	$4.481B
YoY Change	7.78%	6.85%	10.07%
TOTAL ASSETS
Total Short-Term Assets	$351.0M	$306.0M	$258.0M
Total Long-Term Assets	$4.959B	$4.601B	$4.481B
Total Assets	$5.310B	$4.907B	$4.739B
YoY Change	8.21%	4.38%	9.29%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$116.0M	$114.3M	$63.17M
YoY Change	1.75%	1.22%	-23.3%
Accrued Expenses	$49.00M
YoY Change
Deferred Revenue
YoY Change
Short-Term Debt	$120.0M	$105.0M	$130.0M
YoY Change	14.29%	0.0%	271.43%
Long-Term Debt Due	$3.000M	$93.00M	$93.00M
YoY Change	-96.77%	1062.5%	675.0%
Total Short-Term Liabilities	$408.0M	$474.7M	$447.7M
YoY Change	-14.11%	23.21%	65.33%
LONG-TERM LIABILITIES
Long-Term Debt	$1.730B	$1.532B	$1.443B
YoY Change	12.92%	0.0%	-1.43%
Other Long-Term Liabilities	$683.0M	$130.8M	$165.8M
YoY Change	9.28%	-10.54%	37.56%
Total Long-Term Liabilities	$2.413B	$130.8M	$165.8M
YoY Change	11.87%	-10.54%	37.56%
TOTAL LIABILITIES
Total Short-Term Liabilities	$408.0M	$474.7M	$447.7M
Total Long-Term Liabilities	$2.413B	$130.8M	$165.8M
Total Liabilities	$3.661B	$3.378B	$3.231B
YoY Change	8.38%	4.99%	13.58%
SHAREHOLDERS EQUITY
Retained Earnings		$530.9M	$513.0M
YoY Change		8.0%	5.05%
Common Stock		$1.004B	$1.003B
YoY Change		0.44%	-0.5%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$1.649B	$1.529B	$1.508B
YoY Change
Total Liabilities & Shareholders Equity	$5.310B	$4.907B	$4.739B
YoY Change	8.21%	4.38%	9.29%

Cashflow Statement

Concept	2016	2015 Q4	2015 Q3
OPERATING ACTIVITIES
Net Income	$137.2M	$38.52M	$13.01M
YoY Change	11.36%	19.56%	24.5%
Depreciation, Depletion And Amortization	$164.9M	$38.30M	$37.40M
YoY Change	11.56%	8.19%	8.72%
Cash From Operating Activities	$358.3M	$64.40M	$79.10M
YoY Change	-4.62%	3925.0%	89.69%
INVESTING ACTIVITIES
Capital Expenditures	$406.6M	-$120.6M	-$95.40M
YoY Change	3.36%	25.89%	2.03%
Acquisitions	$0.00
YoY Change	-100.0%
Other Investing Activities	$7.631M	$3.900M	-$100.0K
YoY Change	90.44%	-454.55%	-100.52%
Cash From Investing Activities	-$432.5M	-$116.7M	-$95.50M
YoY Change	11.51%	20.43%	29.05%
FINANCING ACTIVITIES
Cash Dividend Paid	$87.15M
YoY Change	5.77%
Common Stock Issuance & Retirement, Net	-$66.95M
YoY Change	-5023.01%
Debt Paid & Issued, Net	$163.2M
YoY Change	5516.76%
Cash From Financing Activities	$72.22M	53.50M	9.400M
YoY Change	13578.41%	-50.05%	-105.69%
NET CHANGE
Cash From Operating Activities	$358.3M	64.40M	79.10M
Cash From Investing Activities	-$432.5M	-116.7M	-95.50M
Cash From Financing Activities	$72.22M	53.50M	9.400M
Net Change In Cash	-$1.977M	1.200M	-7.000M
YoY Change	-83.04%	-89.83%	-96.46%
FREE CASH FLOW
Cash From Operating Activities	$358.3M	$64.40M	$79.10M
Capital Expenditures	$406.6M	-$120.6M	-$95.40M
Free Cash Flow	-$48.38M	$185.0M	$174.5M
YoY Change	172.01%	89.94%	29.07%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2015Q4	ava	Accumulated Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Tax AccumulatedOtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossTax	3580000	USD
CY2016Q4	ava	Accumulated Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Tax AccumulatedOtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossTax	4075000	USD
CY2014	ava	Amortization Of Energy Contract AmortizationOfEnergyContract	12417000	USD
CY2015	ava	Amortization Of Energy Contract AmortizationOfEnergyContract	13508000	USD
CY2016	ava	Amortization Of Energy Contract AmortizationOfEnergyContract	14694000	USD
CY2014Q3	ava	Business Acquisition Contract Price BusinessAcquisitionContractPrice	170000000	USD
CY2014Q3	ava	Business Combination Equity Consideration Share Price BusinessCombinationEquityConsiderationSharePrice	32.46
CY2014Q3	ava	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Capital Lease Assets BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseAssets	71007000	USD
CY2014Q3	ava	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Electric Plant Heldfor Future Use BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedElectricPlantHeldforFutureUse	3711000	USD
CY2014Q3	ava	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Gross Accounts Receivable BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedGrossAccountsReceivable	3928000	USD
CY2014Q3	ava	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Noncurrent Non Utility Property BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentNonUtilityProperty	6660000	USD
CY2014Q3	ava	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Public Utilities Property Plantand Equipment Construction Workin Progress BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPublicUtilitiesPropertyPlantandEquipmentConstructionWorkinProgress	3440000	USD
CY2014Q3	ava	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Public Utilities Property Plantand Equipment Plantin Service BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPublicUtilitiesPropertyPlantandEquipmentPlantinService	113964000	USD
CY2015	ava	Company Shareof Benefit Expense Under Washington Energy Recovery Mechanism CompanyShareofBenefitExpenseUnderWashingtonEnergyRecoveryMechanism	6300000	USD
CY2016	ava	Company Shareof Benefit Expense Under Washington Energy Recovery Mechanism CompanyShareofBenefitExpenseUnderWashingtonEnergyRecoveryMechanism	5100000	USD
CY2015Q4	ava	Current Regulatory Asset For Utility Derivatives CurrentRegulatoryAssetForUtilityDerivatives	17260000	USD
CY2016Q4	ava	Current Regulatory Asset For Utility Derivatives CurrentRegulatoryAssetForUtilityDerivatives	11365000	USD
CY2014	ava	Decreaseincrease In Investmentsand Funds Held For Clients DecreaseincreaseInInvestmentsandFundsHeldForClients	18931000	USD
CY2015	ava	Decreaseincrease In Investmentsand Funds Held For Clients DecreaseincreaseInInvestmentsandFundsHeldForClients	0	USD
CY2016	ava	Decreaseincrease In Investmentsand Funds Held For Clients DecreaseincreaseInInvestmentsandFundsHeldForClients	0	USD
CY2015Q4	ava	Deferred Income Tax Assets Power And Natural Gas Deferrals DeferredIncomeTaxAssetsPowerAndNaturalGasDeferrals	12866000	USD
CY2016Q4	ava	Deferred Income Tax Assets Power And Natural Gas Deferrals DeferredIncomeTaxAssetsPowerAndNaturalGasDeferrals	19415000	USD
CY2014	ava	Deferred Income Tax Expense Benefit Continuing Operationsand Discontinued Operations DeferredIncomeTaxExpenseBenefitContinuingOperationsandDiscontinuedOperations	144269000	USD
CY2015	ava	Deferred Income Tax Expense Benefit Continuing Operationsand Discontinued Operations DeferredIncomeTaxExpenseBenefitContinuingOperationsandDiscontinuedOperations	51801000	USD
CY2016	ava	Deferred Income Tax Expense Benefit Continuing Operationsand Discontinued Operations DeferredIncomeTaxExpenseBenefitContinuingOperationsandDiscontinuedOperations	124543000	USD
CY2015Q4	ava	Deferred Tax Assets Regulatory Deferred Tax Credits DeferredTaxAssetsRegulatoryDeferredTaxCredits	0	USD
CY2016Q4	ava	Deferred Tax Assets Regulatory Deferred Tax Credits DeferredTaxAssetsRegulatoryDeferredTaxCredits	15192000	USD
CY2015Q4	ava	Deferred Tax Liabilities Loss On Reacquired Debt DeferredTaxLiabilitiesLossOnReacquiredDebt	14027000	USD
CY2016Q4	ava	Deferred Tax Liabilities Loss On Reacquired Debt DeferredTaxLiabilitiesLossOnReacquiredDebt	31955000	USD
CY2015Q4	ava	Deferred Tax Liabilities Settlement With Specific External Party DeferredTaxLiabilitiesSettlementWithSpecificExternalParty	12084000	USD
CY2016Q4	ava	Deferred Tax Liabilities Settlement With Specific External Party DeferredTaxLiabilitiesSettlementWithSpecificExternalParty	11711000	USD
CY2015Q4	ava	Deferred Tax Liabilityfor Regulatory Asseton Pensionand Other Postretirement Benefits DeferredTaxLiabilityforRegulatoryAssetonPensionandOtherPostretirementBenefits	82253000	USD
CY2016Q4	ava	Deferred Tax Liabilityfor Regulatory Asseton Pensionand Other Postretirement Benefits DeferredTaxLiabilityforRegulatoryAssetonPensionandOtherPostretirementBenefits	84040000	USD
CY2015Q4	ava	Deferredtaxliabilityforregulatoryassetonutilitypropertyplantandequipment Deferredtaxliabilityforregulatoryassetonutilitypropertyplantandequipment	36917000	USD
CY2016Q4	ava	Deferredtaxliabilityforregulatoryassetonutilitypropertyplantandequipment Deferredtaxliabilityforregulatoryassetonutilitypropertyplantandequipment	37301000	USD
CY2014	ava	Depreciation And Amortization Expense DepreciationAndAmortizationExpense	130180000	USD
CY2015	ava	Depreciation And Amortization Expense DepreciationAndAmortizationExpense	144194000	USD
CY2016	ava	Depreciation And Amortization Expense DepreciationAndAmortizationExpense	161283000	USD
CY2014	ava	Discontinued Operation Gain Loss From Disposal Of Discontinued Operation Before Income Taxes Netof Transaction Costs DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTaxesNetofTransactionCosts	151550000	USD
CY2015	ava	Discontinued Operation Gain Loss From Disposal Of Discontinued Operation Before Income Taxes Netof Transaction Costs DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTaxesNetofTransactionCosts	706000	USD
	ava	Discontinued Operation Transaction Expenses DiscontinuedOperationTransactionExpenses	11100000	USD
CY2014	ava	Escrowreceivableincludedininvestingactivities Escrowreceivableincludedininvestingactivities	13079000	USD
CY2015	ava	Escrowreceivableincludedininvestingactivities Escrowreceivableincludedininvestingactivities	0	USD
CY2016	ava	Escrowreceivableincludedininvestingactivities Escrowreceivableincludedininvestingactivities	0	USD
CY2014	ava	Income Loss From Continuing Operations Excluding Acquired Entity IncomeLossFromContinuingOperationsExcludingAcquiredEntity	116665000	USD
CY2015	ava	Income Loss From Continuing Operations Excluding Acquired Entity IncomeLossFromContinuingOperationsExcludingAcquiredEntity	111772000	USD
CY2016	ava	Income Loss From Continuing Operations Excluding Acquired Entity IncomeLossFromContinuingOperationsExcludingAcquiredEntity	129505000	USD
CY2014	ava	Income Tax Reconciliation Settlementof Share Based Compensation Amount IncomeTaxReconciliationSettlementofShareBasedCompensationAmount	0	USD
CY2015	ava	Income Tax Reconciliation Settlementof Share Based Compensation Amount IncomeTaxReconciliationSettlementofShareBasedCompensationAmount	0	USD
CY2016	ava	Income Tax Reconciliation Settlementof Share Based Compensation Amount IncomeTaxReconciliationSettlementofShareBasedCompensationAmount	1597000	USD
CY2014	ava	Income Tax Reconciliation Settlementof Share Based Compensation Percent IncomeTaxReconciliationSettlementofShareBasedCompensationPercent	0.000
CY2015	ava	Income Tax Reconciliation Settlementof Share Based Compensation Percent IncomeTaxReconciliationSettlementofShareBasedCompensationPercent	0.000
CY2016	ava	Income Tax Reconciliation Settlementof Share Based Compensation Percent IncomeTaxReconciliationSettlementofShareBasedCompensationPercent	0.007
CY2014	ava	Increase Decrease In Client Fund Obligations IncreaseDecreaseInClientFundObligations	16216000	USD
CY2015	ava	Increase Decrease In Client Fund Obligations IncreaseDecreaseInClientFundObligations	0	USD
CY2016	ava	Increase Decrease In Client Fund Obligations IncreaseDecreaseInClientFundObligations	0	USD
CY2014	ava	Increase Decrease In Regulatory Assets And Liabilities Associatedwith Alternative Revenue Programs IncreaseDecreaseInRegulatoryAssetsAndLiabilitiesAssociatedwithAlternativeRevenuePrograms	0	USD
CY2015	ava	Increase Decrease In Regulatory Assets And Liabilities Associatedwith Alternative Revenue Programs IncreaseDecreaseInRegulatoryAssetsAndLiabilitiesAssociatedwithAlternativeRevenuePrograms	10933000	USD
CY2016	ava	Increase Decrease In Regulatory Assets And Liabilities Associatedwith Alternative Revenue Programs IncreaseDecreaseInRegulatoryAssetsAndLiabilitiesAssociatedwithAlternativeRevenuePrograms	29789000	USD
CY2014	ava	Interest Expense Including Affiliated Trusts InterestExpenseIncludingAffiliatedTrusts	75752000	USD
CY2015	ava	Interest Expense Including Affiliated Trusts InterestExpenseIncludingAffiliatedTrusts	80441000	USD
CY2016	ava	Interest Expense Including Affiliated Trusts InterestExpenseIncludingAffiliatedTrusts	87130000	USD
CY2014	ava	Interest On Regulatory Deferrals InterestOnRegulatoryDeferrals	220000	USD
CY2015	ava	Interest On Regulatory Deferrals InterestOnRegulatoryDeferrals	48000	USD
CY2016	ava	Interest On Regulatory Deferrals InterestOnRegulatoryDeferrals	1308000	USD
CY2015Q4	ava	Long Term Debt Before Current Portion And Bonds Held By Company LongTermDebtBeforeCurrentPortionAndBondsHeldByCompany	1656978000	USD
CY2016Q4	ava	Long Term Debt Before Current Portion And Bonds Held By Company LongTermDebtBeforeCurrentPortionAndBondsHeldByCompany	1765704000	USD
CY2014	ava	Noncash Change In Redeemable Noncontrolling Interests NoncashChangeInRedeemableNoncontrollingInterests	-15873000	USD
CY2015	ava	Noncash Change In Redeemable Noncontrolling Interests NoncashChangeInRedeemableNoncontrollingInterests	0	USD
CY2016	ava	Noncash Change In Redeemable Noncontrolling Interests NoncashChangeInRedeemableNoncontrollingInterests	0	USD
CY2015Q4	ava	Noncurrent Regulatory Asset For Utility Derivatives NoncurrentRegulatoryAssetForUtilityDerivatives	32420000	USD
CY2016Q4	ava	Noncurrent Regulatory Asset For Utility Derivatives NoncurrentRegulatoryAssetForUtilityDerivatives	16919000	USD
CY2016	ava	Number Of Days Canadian Currency Prices Are Settled With Us Dollars NumberOfDaysCanadianCurrencyPricesAreSettledWithUSDollars	P60D
CY2014	ava	Other Comprehensive Income Reclassification Adjustment From Aoci For Sale Securities Netof Tax OtherComprehensiveIncomeReclassificationAdjustmentFromAOCIForSaleSecuritiesNetofTax	462000	USD
CY2015	ava	Other Comprehensive Income Reclassification Adjustment From Aoci For Sale Securities Netof Tax OtherComprehensiveIncomeReclassificationAdjustmentFromAOCIForSaleSecuritiesNetofTax	0	USD
CY2016	ava	Other Comprehensive Income Reclassification Adjustment From Aoci For Sale Securities Netof Tax OtherComprehensiveIncomeReclassificationAdjustmentFromAOCIForSaleSecuritiesNetofTax	0	USD
CY2014	ava	Other Comprehensive Income Reclassification Adjustmentfrom Aoc Ifor Saleof Securities Tax OtherComprehensiveIncomeReclassificationAdjustmentfromAOCIforSaleofSecuritiesTax	273000	USD
CY2015	ava	Other Comprehensive Income Reclassification Adjustmentfrom Aoc Ifor Saleof Securities Tax OtherComprehensiveIncomeReclassificationAdjustmentfromAOCIforSaleofSecuritiesTax	0	USD
CY2016	ava	Other Comprehensive Income Reclassification Adjustmentfrom Aoc Ifor Saleof Securities Tax OtherComprehensiveIncomeReclassificationAdjustmentfromAOCIforSaleofSecuritiesTax	0	USD
CY2014	ava	Other Operating Expenses OtherOperatingExpenses	317250000	USD
CY2015	ava	Other Operating Expenses OtherOperatingExpenses	332747000	USD
CY2016	ava	Other Operating Expenses OtherOperatingExpenses	341296000	USD
CY2014	ava	Payments For Proceeds From Derivative Instrument Operating Activities PaymentsForProceedsFromDerivativeInstrumentOperatingActivities	0	USD
CY2015	ava	Payments For Proceeds From Derivative Instrument Operating Activities PaymentsForProceedsFromDerivativeInstrumentOperatingActivities	0	USD
CY2016	ava	Payments For Proceeds From Derivative Instrument Operating Activities PaymentsForProceedsFromDerivativeInstrumentOperatingActivities	53966000	USD
CY2016Q4	ava	Pending Regulatory Treatment Liability PendingRegulatoryTreatmentLiability	15349000	USD
CY2015Q4	ava	Property Plant And Equipment Total PropertyPlantAndEquipmentTotal	5357584000	USD
CY2016Q4	ava	Property Plant And Equipment Total PropertyPlantAndEquipmentTotal	5687737000	USD
CY2014	ava	Public Utility Operating Expenses Excise Taxes Collected PublicUtilityOperatingExpensesExciseTaxesCollected	58250000	USD
CY2015	ava	Public Utility Operating Expenses Excise Taxes Collected PublicUtilityOperatingExpensesExciseTaxesCollected	59173000	USD
CY2016	ava	Public Utility Operating Expenses Excise Taxes Collected PublicUtilityOperatingExpensesExciseTaxesCollected	57745000	USD
CY2014	ava	Public Utility Operating Expenses Other Taxes PublicUtilityOperatingExpensesOtherTaxes	2118000	USD
CY2015	ava	Public Utility Operating Expenses Other Taxes PublicUtilityOperatingExpensesOtherTaxes	2536000	USD
CY2016	ava	Public Utility Operating Expenses Other Taxes PublicUtilityOperatingExpensesOtherTaxes	2485000	USD
CY2015Q4	ava	Receivables Long Term Contracts Or Programs Noncurrent ReceivablesLongTermContractsOrProgramsNoncurrent	14694000	USD
CY2016Q4	ava	Receivables Long Term Contracts Or Programs Noncurrent ReceivablesLongTermContractsOrProgramsNoncurrent	0	USD
CY2016Q4	ava	Regulatory Asset Earning Return RegulatoryAssetEarningReturn	270641000	USD
CY2015Q4	ava	Regulatory Asset For Interest Rate Swap Agreements Noncurrent RegulatoryAssetForInterestRateSwapAgreementsNoncurrent	83973000	USD
CY2016Q4	ava	Regulatory Asset For Interest Rate Swap Agreements Noncurrent RegulatoryAssetForInterestRateSwapAgreementsNoncurrent	161508000	USD
CY2015Q4	ava	Regulatory Assetfor Deferred Income Taxes Noncurrent RegulatoryAssetforDeferredIncomeTaxesNoncurrent	101240000	USD
CY2016Q4	ava	Regulatory Assetfor Deferred Income Taxes Noncurrent RegulatoryAssetforDeferredIncomeTaxesNoncurrent	109853000	USD
CY2015Q4	ava	Regulatory Assets For Pensions And Other Postretirement Benefits Noncurrent RegulatoryAssetsForPensionsAndOtherPostretirementBenefitsNoncurrent	235009000	USD
CY2016Q4	ava	Regulatory Assets For Pensions And Other Postretirement Benefits Noncurrent RegulatoryAssetsForPensionsAndOtherPostretirementBenefitsNoncurrent	240114000	USD
CY2016Q4	ava	Regulatory Liability Earning Return RegulatoryLiabilityEarningReturn	345683000	USD
CY2015Q4	ava	Regulatory Liability For Utility Plant Retirement Costs Noncurrent RegulatoryLiabilityForUtilityPlantRetirementCostsNoncurrent	261594000	USD
CY2016Q4	ava	Regulatory Liability For Utility Plant Retirement Costs Noncurrent RegulatoryLiabilityForUtilityPlantRetirementCostsNoncurrent	273983000	USD
CY2016Q4	ava	Remaining Amounts Of Regulatory Liabilities For Which No Interest During Recovery Period Is Provided RemainingAmountsOfRegulatoryLiabilitiesForWhichNoInterestDuringRecoveryPeriodIsProvided	35920000	USD
CY2014	ava	Revenues Excluding Acquired Entity RevenuesExcludingAcquiredEntity	1450918000	USD
CY2015	ava	Revenues Excluding Acquired Entity RevenuesExcludingAcquiredEntity	1439807000	USD
CY2016	ava	Revenues Excluding Acquired Entity RevenuesExcludingAcquiredEntity	1395989000	USD
CY2015Q4	ava	Securedand Unsecured Debt SecuredandUnsecuredDebt	1626700000	USD
CY2016Q4	ava	Securedand Unsecured Debt SecuredandUnsecuredDebt	1711700000	USD
CY2015Q4	ava	Settled Interest Rate Swaps SettledInterestRateSwaps	26515000	USD
CY2016Q4	ava	Settled Interest Rate Swaps SettledInterestRateSwaps	0	USD
CY2014	ava	Stock Issued During Period Value Acquisitions Netof Issuance Costs StockIssuedDuringPeriodValueAcquisitionsNetofIssuanceCosts	149625000	USD
CY2015	ava	Stock Issued During Period Value Acquisitions Netof Issuance Costs StockIssuedDuringPeriodValueAcquisitionsNetofIssuanceCosts	0	USD
CY2016	ava	Stock Issued During Period Value Acquisitions Netof Issuance Costs StockIssuedDuringPeriodValueAcquisitionsNetofIssuanceCosts	0	USD
CY2016Q4	ava	Tax Credit Carryforwards Netof Valuation Allowance TaxCreditCarryforwardsNetofValuationAllowance	9200000	USD
CY2014	ava	Tax Effect Of Regulatory Treatment Of Utility Plant Differences TaxEffectOfRegulatoryTreatmentOfUtilityPlantDifferences	4008000	USD
CY2015	ava	Tax Effect Of Regulatory Treatment Of Utility Plant Differences TaxEffectOfRegulatoryTreatmentOfUtilityPlantDifferences	4358000	USD
CY2016	ava	Tax Effect Of Regulatory Treatment Of Utility Plant Differences TaxEffectOfRegulatoryTreatmentOfUtilityPlantDifferences	3297000	USD
CY2014	ava	Tax Effect Of Regulatory Treatment Of Utility Plant Differences Percent TaxEffectOfRegulatoryTreatmentOfUtilityPlantDifferencesPercent	0.021
CY2015	ava	Tax Effect Of Regulatory Treatment Of Utility Plant Differences Percent TaxEffectOfRegulatoryTreatmentOfUtilityPlantDifferencesPercent	0.023
CY2016	ava	Tax Effect Of Regulatory Treatment Of Utility Plant Differences Percent TaxEffectOfRegulatoryTreatmentOfUtilityPlantDifferencesPercent	0.015
	ava	Transaction Expenses Withheldfrom Sales Proceeds TransactionExpensesWithheldfromSalesProceeds	5500000	USD
CY2014	ava	Utility Power Resources UtilityPowerResources	556915000	USD
CY2015	ava	Utility Power Resources UtilityPowerResources	511937000	USD
CY2016	ava	Utility Power Resources UtilityPowerResources	402575000	USD
CY2016	dei	Amendment Flag AmendmentFlag	false
CY2016	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2016	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2016	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2016
CY2016	dei	Document Period End Date DocumentPeriodEndDate	2016-12-31
CY2016	dei	Document Type DocumentType	10-K
CY2016	dei	Entity Central Index Key EntityCentralIndexKey	0000104918
CY2017Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	64311891	shares
CY2016	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2016	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2016Q2	dei	Entity Public Float EntityPublicFloat	2853952416	USD
CY2016	dei	Entity Registrant Name EntityRegistrantName	AVISTA CORP
CY2016	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2016	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2016	dei	Trading Symbol TradingSymbol	ava
CY2015Q4	us-gaap	Accounts Notes And Loans Receivable Net Current AccountsNotesAndLoansReceivableNetCurrent	169413000	USD
CY2016Q4	us-gaap	Accounts Notes And Loans Receivable Net Current AccountsNotesAndLoansReceivableNetCurrent	180265000	USD
CY2015Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	114349000	USD
CY2016Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	115545000	USD
CY2015Q4	us-gaap	Accrual For Taxes Other Than Income Taxes Current AccrualForTaxesOtherThanIncomeTaxesCurrent	30978000	USD
CY2016Q4	us-gaap	Accrual For Taxes Other Than Income Taxes Current AccrualForTaxesOtherThanIncomeTaxesCurrent	33374000	USD
CY2015Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	-6650000	USD
CY2016Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	-7568000	USD
CY2015Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-6650000	USD
CY2016Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-7568000	USD
CY2014	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	6007000	USD
CY2015	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	6914000	USD
CY2016	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	7891000	USD
CY2013Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	44309000	USD
CY2014Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	4888000	USD
CY2015Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	4530000	USD
CY2016Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	5026000	USD
CY2014	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	3692000	USD
CY2015	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	3526000	USD
CY2016	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	3477000	USD
CY2014	us-gaap	Amortization Of Power Contracts Emission Credits AmortizationOfPowerContractsEmissionCredits	2450000	USD
CY2015	us-gaap	Amortization Of Power Contracts Emission Credits AmortizationOfPowerContractsEmissionCredits	2450000	USD
CY2016	us-gaap	Amortization Of Power Contracts Emission Credits AmortizationOfPowerContractsEmissionCredits	2450000	USD
CY2016Q4	us-gaap	Amount Of Regulatory Costs Not Yet Approved AmountOfRegulatoryCostsNotYetApproved	128181000	USD
CY2013Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	2859000	USD
CY2014Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	3028000	USD
CY2015Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	15997000	USD
CY2016Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	15515000	USD
CY2014	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	210000	USD
CY2015	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	459000	USD
CY2016	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	617000	USD
CY2014	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	0	USD
CY2015	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	12539000	USD
CY2016	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	430000	USD
CY2014	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	41000	USD
CY2015	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	29000	USD
CY2016	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	1529000	USD
CY2014Q4	us-gaap	Assets Assets	4700971000	USD
CY2015Q4	us-gaap	Assets Assets	4906649000	USD
CY2016Q4	us-gaap	Assets Assets	5309755000	USD
CY2015Q4	us-gaap	Assets Current AssetsCurrent	306046000	USD
CY2016Q4	us-gaap	Assets Current AssetsCurrent	351341000	USD
CY2014Q4	us-gaap	Business Acquisition Equity Interests Issued Or Issuable Number Of Shares Issued BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued	4501441	shares
CY2014	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	198565000	USD
CY2015	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	123249000	USD
CY2016	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	137228000	USD
CY2014	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	1497385000	USD
CY2015	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	1484776000	USD
CY2016	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	1442483000	USD
CY2014Q3	us-gaap	Business Combination Consideration Transferred1 BusinessCombinationConsiderationTransferred1	154900000	USD
CY2014	us-gaap	Business Combination Pro Forma Information Earnings Or Loss Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual	3152000	USD
CY2015	us-gaap	Business Combination Pro Forma Information Earnings Or Loss Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual	6308000	USD
CY2016	us-gaap	Business Combination Pro Forma Information Earnings Or Loss Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual	7723000	USD
CY2014	us-gaap	Business Combination Pro Forma Information Revenue Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual	21644000	USD
CY2015	us-gaap	Business Combination Pro Forma Information Revenue Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual	44969000	USD
CY2016	us-gaap	Business Combination Pro Forma Information Revenue Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual	46494000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Assets BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets	283147000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Capital Lease Obligation BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation	68840000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Cash And Equivalents BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents	19704000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Assets BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets	26571000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Assets Other BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther	999000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Assets Receivables BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables	3851000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Liabilities BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities	7280000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Liabilities Accounts Payable BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable	700000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Liabilities Long Term Debt BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt	3773000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Liabilities Other BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther	2807000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Inventory BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory	2017000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Liabilities BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities	128236000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Net BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet	154911000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Noncurrent Assets BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssets	68165000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Noncurrent Liabilities BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilities	14889000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Noncurrent Liabilities Long Term Debt BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt	37227000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Other Noncurrent Assets BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets	5368000	USD
CY2014Q3	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Property Plant And Equipment BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment	188411000	USD
CY2014	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	26959000	USD
CY2015	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	35248000	USD
CY2016	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	30252000	USD
CY2015Q4	us-gaap	Capital Lease Obligations CapitalLeaseObligations	68601000	USD
CY2016Q4	us-gaap	Capital Lease Obligations CapitalLeaseObligations	65435000	USD
CY2014	us-gaap	Cash Acquired In Excess Of Payments To Acquire Business CashAcquiredInExcessOfPaymentsToAcquireBusiness	15007000	USD
CY2013Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	82574000	USD
CY2014Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	22143000	USD
CY2015Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	10484000	USD
CY2016Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	8507000	USD
CY2014	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-60431000	USD
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CY2016	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-1977000	USD
CY2015Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
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CY2014	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.27
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CY2016	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.37
CY2015Q4	us-gaap	Common Stock No Par Value CommonStockNoParValue	0
CY2016Q4	us-gaap	Common Stock No Par Value CommonStockNoParValue	0
CY2015Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	200000000	shares
CY2016Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	200000000	shares
CY2015Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	62312651	shares
CY2016Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	64187934	shares
CY2015Q4	us-gaap	Common Stock Value CommonStockValue	1004336000	USD
CY2016Q4	us-gaap	Common Stock Value CommonStockValue	1075281000	USD
CY2014	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	189972000	USD
CY2015	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	124465000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	136310000	USD
CY2014	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	236000	USD
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CY2015Q3	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	32000	USD
CY2015Q4	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	17000	USD
CY2015	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	90000	USD
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CY2014	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	190208000	USD
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CY2016	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	136398000	USD
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CY2015Q4	us-gaap	Costs And Expenses CostsAndExpenses	316938000	USD
CY2015	us-gaap	Costs And Expenses CostsAndExpenses	1231562000	USD
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CY2016Q4	us-gaap	Costs And Expenses CostsAndExpenses	319590000	USD
CY2016	us-gaap	Costs And Expenses CostsAndExpenses	1152680000	USD
CY2014	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	-67059000	USD
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CY2016	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	-46457000	USD
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CY2015Q4	us-gaap	Debt Instrument Unamortized Discount DebtInstrumentUnamortizedDiscount	956000	USD
CY2016Q4	us-gaap	Debt Instrument Unamortized Discount DebtInstrumentUnamortizedDiscount	792000	USD
CY2014	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	139299000	USD
CY2015	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	55237000	USD
CY2016	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	124543000	USD
CY2015Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	935042000	USD
CY2016Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	1048275000	USD
CY2015Q4	us-gaap	Deferred Tax Assets Derivative Instruments DeferredTaxAssetsDerivativeInstruments	47009000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Derivative Instruments DeferredTaxAssetsDerivativeInstruments	31872000	USD
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CY2016Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	215293000	USD
CY2015Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	187565000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	207347000	USD
CY2015Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	29471000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	29512000	USD
CY2015Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards DeferredTaxAssetsTaxCreditCarryforwards	15011000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards DeferredTaxAssetsTaxCreditCarryforwards	27931000	USD
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CY2015Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	2862000	USD
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CY2015Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	747477000	USD
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CY2015Q4	us-gaap	Deferred Tax Liabilities Derivatives DeferredTaxLiabilitiesDerivatives	47010000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Derivatives DeferredTaxLiabilitiesDerivatives	31871000	USD
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CY2016	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Decrease On Service And Interest Cost Components1 DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnServiceAndInterestCostComponents1	700000	USD
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CY2016	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Increase On Service And Interest Cost Components DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnServiceAndInterestCostComponents	1000000	USD
CY2014	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	6862000	USD
CY2015	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	8011000	USD
CY2016	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	8710000	USD
CY2014	us-gaap	Depreciation And Amortization DepreciationAndAmortization	610000	USD
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CY2014	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	138337000	USD
CY2015	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	147835000	USD
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CY2015Q4	us-gaap	Derivative Assets Liabilities At Fair Value Net DerivativeAssetsLiabilitiesAtFairValueNet	-85091000	USD
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CY2015Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	76865000	USD
CY2016Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	61191000	USD
CY2015Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	210512000	USD
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CY2014	us-gaap	Dilutive Securities DilutiveSecurities	5000	USD
CY2015	us-gaap	Dilutive Securities DilutiveSecurities	0	USD
CY2016	us-gaap	Dilutive Securities DilutiveSecurities	0	USD
CY2014	us-gaap	Discontinued Operation Gain Loss From Disposal Of Discontinued Operation Before Income Tax DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax	160612000	USD
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CY2014	us-gaap	Discontinued Operation Gain Loss On Disposal Of Discontinued Operation Net Of Tax DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax	69700000	USD
CY2014	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Before Income Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax	156025000	USD
CY2015	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Before Income Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax	706000	USD
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CY2015Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.40
CY2015Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.21
CY2015Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.61
CY2015	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.97
CY2016Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.92
CY2016Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.43
CY2016Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.19
CY2016Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.62
CY2016	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.15
CY2014	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.376
CY2015	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.363
CY2016	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.363
CY2014	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.350
CY2014	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2015	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
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
CY2016	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2014	us-gaap	Effective Income Tax Rate Reconciliation Deductions Qualified Production Activities EffectiveIncomeTaxRateReconciliationDeductionsQualifiedProductionActivities	0.001
CY2015	us-gaap	Effective Income Tax Rate Reconciliation Deductions Qualified Production Activities EffectiveIncomeTaxRateReconciliationDeductionsQualifiedProductionActivities	0.006
CY2016	us-gaap	Effective Income Tax Rate Reconciliation Deductions Qualified Production Activities EffectiveIncomeTaxRateReconciliationDeductionsQualifiedProductionActivities	0.000
CY2014	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.002
CY2015	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.004
CY2016	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.001
CY2014	us-gaap	Effective Income Tax Rate Reconciliation Prior Year Income Taxes EffectiveIncomeTaxRateReconciliationPriorYearIncomeTaxes	0.006
CY2015	us-gaap	Effective Income Tax Rate Reconciliation Prior Year Income Taxes EffectiveIncomeTaxRateReconciliationPriorYearIncomeTaxes	-0.005
CY2016	us-gaap	Effective Income Tax Rate Reconciliation Prior Year Income Taxes EffectiveIncomeTaxRateReconciliationPriorYearIncomeTaxes	0.000
CY2014	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.002
CY2015	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.005
CY2016	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.006
CY2014	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	2102000	USD
CY2015	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	2420000	USD
CY2016	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	4359000	USD
CY2016	us-gaap	Employee Service Share Based Compensation Tax Benefit Realized From Exercise Of Stock Options EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions	1600000	USD
CY2015Q4	us-gaap	Energy Marketing Contract Liabilities Current EnergyMarketingContractLiabilitiesCurrent	14268000	USD
CY2016Q4	us-gaap	Energy Marketing Contract Liabilities Current EnergyMarketingContractLiabilitiesCurrent	7035000	USD
CY2015Q4	us-gaap	Energy Related Inventory Natural Gas In Storage EnergyRelatedInventoryNaturalGasInStorage	12774000	USD
CY2016Q4	us-gaap	Energy Related Inventory Natural Gas In Storage EnergyRelatedInventoryNaturalGasInStorage	8029000	USD
CY2016Q4	us-gaap	Equity Method Investment Ownership Percentage EquityMethodInvestmentOwnershipPercentage	1
CY2014	us-gaap	Gain Loss On Investments GainLossOnInvestments	276000	USD
CY2015	us-gaap	Gain Loss On Investments GainLossOnInvestments	-637000	USD
CY2016	us-gaap	Gain Loss On Investments GainLossOnInvestments	-2152000	USD
CY2014Q4	us-gaap	Goodwill Goodwill	57976000	USD
CY2015Q4	us-gaap	Goodwill Goodwill	57672000	USD
CY2016Q4	us-gaap	Goodwill Goodwill	57672000	USD
CY2014Q3	us-gaap	Goodwill Goodwill	52426000	USD
CY2015	us-gaap	Goodwill Purchase Accounting Adjustments GoodwillPurchaseAccountingAdjustments	-304000	USD
CY2014	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	119817000	USD
CY2015Q1	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	46449000	USD
CY2015Q2	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	25050000	USD
CY2015Q3	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	12722000	USD
CY2015Q4	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	33859000	USD
CY2015	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	118080000	USD
CY2016	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	137228000	USD
CY2014	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	192106000	USD
CY2015	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	185619000	USD
CY2016	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	215402000	USD
CY2014	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	119866000	USD
CY2015Q1	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	46462000	USD
CY2015Q2	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	25078000	USD
CY2015Q3	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	12754000	USD
CY2015Q4	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	33876000	USD
CY2015	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	118170000	USD
CY2016	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	137316000	USD
CY2014	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	1.94
CY2015	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	1.90
CY2016	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	2.16
CY2014	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	1.93
CY2015Q1	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.74
CY2015Q2	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.40
CY2015Q3	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.21
CY2015Q4	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.54
CY2015	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	1.89
CY2016	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	2.15
CY2014	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	72411000	USD
CY2015Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	0	USD
CY2015Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	196000	USD
CY2015Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	289000	USD
CY2015Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	4662000	USD
CY2015	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	5147000	USD
CY2016	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	0	USD
CY2014	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	72224000	USD
CY2015Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	USD
CY2015Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	196000	USD
CY2015Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	289000	USD
CY2015Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	4662000	USD
CY2015	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	5147000	USD
CY2016	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	USD
CY2014	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	1.18
CY2015	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.08
CY2016	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.00
CY2014	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	1.17
CY2015Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.00
CY2015Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.00
CY2015Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.00
CY2015Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.07
CY2015	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.08
CY2016	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.00
CY2014	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	72240000	USD
CY2015	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	67449000	USD
CY2016	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	78086000	USD
CY2014	us-gaap	Income Tax Reconciliation Deductions Qualified Production Activities IncomeTaxReconciliationDeductionsQualifiedProductionActivities	169000	USD
CY2015	us-gaap	Income Tax Reconciliation Deductions Qualified Production Activities IncomeTaxReconciliationDeductionsQualifiedProductionActivities	1198000	USD
CY2016	us-gaap	Income Tax Reconciliation Deductions Qualified Production Activities IncomeTaxReconciliationDeductionsQualifiedProductionActivities	0	USD
CY2014	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	67237000	USD
CY2015	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	64967000	USD
CY2016	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	75391000	USD
CY2014	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-446000	USD
CY2015	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-698000	USD
CY2016	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-334000	USD
CY2014	us-gaap	Income Tax Reconciliation Prior Year Income Taxes IncomeTaxReconciliationPriorYearIncomeTaxes	1104000	USD
CY2015	us-gaap	Income Tax Reconciliation Prior Year Income Taxes IncomeTaxReconciliationPriorYearIncomeTaxes	-992000	USD
CY2016	us-gaap	Income Tax Reconciliation Prior Year Income Taxes IncomeTaxReconciliationPriorYearIncomeTaxes	13000	USD
CY2014	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	506000	USD
CY2015	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	1012000	USD
CY2016	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	1316000	USD
CY2014	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	45416000	USD
CY2015	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-9961000	USD
CY2016	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-13458000	USD
CY2015Q4	us-gaap	Income Taxes Receivable IncomeTaxesReceivable	24121000	USD
CY2016Q4	us-gaap	Income Taxes Receivable IncomeTaxesReceivable	48265000	USD
CY2014	us-gaap	Increase Decrease In Accounts And Notes Receivable IncreaseDecreaseInAccountsAndNotesReceivable	16425000	USD
CY2015	us-gaap	Increase Decrease In Accounts And Notes Receivable IncreaseDecreaseInAccountsAndNotesReceivable	-10538000	USD
CY2016	us-gaap	Increase Decrease In Accounts And Notes Receivable IncreaseDecreaseInAccountsAndNotesReceivable	-17170000	USD
CY2014	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-12562000	USD
CY2015	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-8138000	USD
CY2016	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	5176000	USD
CY2015	us-gaap	Increase Decrease In Deposit Other Assets IncreaseDecreaseInDepositOtherAssets	-13301000	USD
CY2014	us-gaap	Increase Decrease In Deposit Other Assets IncreaseDecreaseInDepositOtherAssets	-23301000	USD
CY2016	us-gaap	Increase Decrease In Deposit Other Assets IncreaseDecreaseInDepositOtherAssets	10712000	USD
CY2014	us-gaap	Increase Decrease In Income Taxes Receivable IncreaseDecreaseInIncomeTaxesReceivable	-36110000	USD
CY2015	us-gaap	Increase Decrease In Income Taxes Receivable IncreaseDecreaseInIncomeTaxesReceivable	19772000	USD
CY2016	us-gaap	Increase Decrease In Income Taxes Receivable IncreaseDecreaseInIncomeTaxesReceivable	-33923000	USD
CY2014	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-19394000	USD
CY2015	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	12208000	USD
CY2016	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	834000	USD
CY2014	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-7117000	USD
CY2015	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	2338000	USD
CY2016	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-3907000	USD
CY2014	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	32060000	USD
CY2015	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-6471000	USD
CY2016	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	10546000	USD
CY2014	us-gaap	Increase Decrease In Regulatory Assets And Liabilities IncreaseDecreaseInRegulatoryAssetsAndLiabilities	-7906000	USD
CY2015	us-gaap	Increase Decrease In Regulatory Assets And Liabilities IncreaseDecreaseInRegulatoryAssetsAndLiabilities	-4569000	USD
CY2016	us-gaap	Increase Decrease In Regulatory Assets And Liabilities IncreaseDecreaseInRegulatoryAssetsAndLiabilities	26245000	USD
CY2014	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	255000	shares
CY2015	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	407000	shares
CY2016	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	412000	shares
CY2014	us-gaap	Interest Expense InterestExpense	75302000	USD
CY2015	us-gaap	Interest Expense InterestExpense	79968000	USD
CY2016	us-gaap	Interest Expense InterestExpense	86496000	USD
CY2014	us-gaap	Interest Expense Other InterestExpenseOther	450000	USD
CY2015	us-gaap	Interest Expense Other InterestExpenseOther	473000	USD
CY2016	us-gaap	Interest Expense Other InterestExpenseOther	634000	USD
CY2014	us-gaap	Interest Paid InterestPaid	73526000	USD
CY2015	us-gaap	Interest Paid InterestPaid	79673000	USD
CY2016	us-gaap	Interest Paid InterestPaid	86319000	USD
CY2015Q4	us-gaap	Interest Payable Current InterestPayableCurrent	15378000	USD
CY2016Q4	us-gaap	Interest Payable Current InterestPayableCurrent	15869000	USD
CY2015Q4	us-gaap	Inventory Net InventoryNet	54148000	USD
CY2016Q4	us-gaap	Inventory Net InventoryNet	53314000	USD
CY2015Q4	us-gaap	Inventory Raw Materials And Supplies InventoryRawMaterialsAndSupplies	37101000	USD
CY2016Q4	us-gaap	Inventory Raw Materials And Supplies InventoryRawMaterialsAndSupplies	40700000	USD
CY2014	us-gaap	Investment Income Interest InvestmentIncomeInterest	987000	USD
CY2015	us-gaap	Investment Income Interest InvestmentIncomeInterest	653000	USD
CY2016	us-gaap	Investment Income Interest InvestmentIncomeInterest	1823000	USD
CY2015Q4	us-gaap	Investments And Other Noncurrent Assets InvestmentsAndOtherNoncurrentAssets	59733000	USD
CY2016Q4	us-gaap	Investments And Other Noncurrent Assets InvestmentsAndOtherNoncurrentAssets	72224000	USD
CY2015Q4	us-gaap	Investments In Affiliates Subsidiaries Associates And Joint Ventures InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures	11547000	USD
CY2016Q4	us-gaap	Investments In Affiliates Subsidiaries Associates And Joint Ventures InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures	11547000	USD
CY2016Q4	us-gaap	Jointly Owned Utility Plant Proportionate Ownership Share JointlyOwnedUtilityPlantProportionateOwnershipShare	0.15
CY2016Q4	us-gaap	Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust	51500000	USD
CY1997Q4	us-gaap	Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust	51500000	USD
CY2015Q4	us-gaap	Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust Noncurrent JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrustNoncurrent	51547000	USD
CY2016Q4	us-gaap	Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust Noncurrent JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrustNoncurrent	51547000	USD
CY2015Q4	us-gaap	Liabilities Liabilities	3378362000	USD
CY2016Q4	us-gaap	Liabilities Liabilities	3661279000	USD
CY2015Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	4906649000	USD
CY2016Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	5309755000	USD
CY2015Q4	us-gaap	Liabilities Current LiabilitiesCurrent	474680000	USD
CY2016Q4	us-gaap	Liabilities Current LiabilitiesCurrent	407528000	USD
CY2015Q4	us-gaap	Number Of Foreign Currency Derivatives Held NumberOfForeignCurrencyDerivativesHeld	24
CY2016Q4	us-gaap	Number Of Foreign Currency Derivatives Held NumberOfForeignCurrencyDerivativesHeld	21
CY2016	us-gaap	Number Of Reportable Segments NumberOfReportableSegments	2	Reportable_Segments
CY2014	us-gaap	Operating Income Loss OperatingIncomeLoss	252588000	USD
CY2015Q4	us-gaap	Lines Of Credit Current LinesOfCreditCurrent	105000000	USD
CY2016Q4	us-gaap	Lines Of Credit Current LinesOfCreditCurrent	120000000	USD
CY2014	us-gaap	Litigation Settlement Amount LitigationSettlementAmount	15000000	USD
CY2016	us-gaap	Long Term Contract For Purchase Of Electric Power Amount Of Long Term Debt Or Lease Obligation Outstanding LongTermContractForPurchaseOfElectricPowerAmountOfLongTermDebtOrLeaseObligationOutstanding	65200000	USD
CY2015Q4	us-gaap	Long Term Debt And Capital Lease Obligations LongTermDebtAndCapitalLeaseObligations	1480111000	USD
CY2016Q4	us-gaap	Long Term Debt And Capital Lease Obligations LongTermDebtAndCapitalLeaseObligations	1678717000	USD
CY2015Q4	us-gaap	Long Term Debt And Capital Lease Obligations Current LongTermDebtAndCapitalLeaseObligationsCurrent	93167000	USD
CY2016Q4	us-gaap	Long Term Debt And Capital Lease Obligations Current LongTermDebtAndCapitalLeaseObligationsCurrent	3287000	USD
CY2015Q4	us-gaap	Long Term Pollution Control Bond LongTermPollutionControlBond	-83700000	USD
CY2016Q4	us-gaap	Long Term Pollution Control Bond LongTermPollutionControlBond	-83700000	USD
CY2015Q4	us-gaap	Minority Interest MinorityInterest	339000	USD
CY2016Q4	us-gaap	Minority Interest MinorityInterest	251000	USD
CY2014	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	23612000	USD
CY2015	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	0	USD
CY2016	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	0	USD
CY2014	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-223963000	USD
CY2015	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	528000	USD
CY2016	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	72222000	USD
CY2014	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-103736000	USD
CY2015	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-387827000	USD
CY2016	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-432466000	USD
CY2014	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	267268000	USD
CY2015	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	375640000	USD
CY2016	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	358267000	USD
CY2014	us-gaap	Net Income Loss NetIncomeLoss	192041000	USD
CY2015Q1	us-gaap	Net Income Loss NetIncomeLoss	46449000	USD
CY2015Q2	us-gaap	Net Income Loss NetIncomeLoss	25246000	USD
CY2015Q3	us-gaap	Net Income Loss NetIncomeLoss	13011000	USD
CY2015Q4	us-gaap	Net Income Loss NetIncomeLoss	38521000	USD
CY2015	us-gaap	Net Income Loss NetIncomeLoss	123227000	USD
CY2016Q1	us-gaap	Net Income Loss NetIncomeLoss	57649000	USD
CY2016Q2	us-gaap	Net Income Loss NetIncomeLoss	27254000	USD
CY2016Q3	us-gaap	Net Income Loss NetIncomeLoss	12234000	USD
CY2016Q4	us-gaap	Net Income Loss NetIncomeLoss	40091000	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	137228000	USD
CY2014	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	72229000	USD
CY2015	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	5147000	USD
CY2016	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	0	USD
CY2015Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	89575000	USD
CY2015Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	57360000	USD
CY2015Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	35912000	USD
CY2015Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	70367000	USD
CY2015	us-gaap	Operating Income Loss OperatingIncomeLoss	253214000	USD
CY2016Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	106085000	USD
CY2016Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	61591000	USD
CY2016Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	39594000	USD
CY2016Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	82533000	USD
CY2016	us-gaap	Operating Income Loss OperatingIncomeLoss	289803000	USD
CY2014	us-gaap	Other Amortization Of Deferred Charges OtherAmortizationOfDeferredCharges	-14821000	USD
CY2015	us-gaap	Other Amortization Of Deferred Charges OtherAmortizationOfDeferredCharges	21358000	USD
CY2016	us-gaap	Other Amortization Of Deferred Charges OtherAmortizationOfDeferredCharges	16835000	USD
CY2015Q4	us-gaap	Other Assets Current OtherAssetsCurrent	30620000	USD
CY2016Q4	us-gaap	Other Assets Current OtherAssetsCurrent	49625000	USD
CY2015Q4	us-gaap	Other Assets Miscellaneous Noncurrent OtherAssetsMiscellaneousNoncurrent	5928000	USD
CY2016Q4	us-gaap	Other Assets Miscellaneous Noncurrent OtherAssetsMiscellaneousNoncurrent	5326000	USD
CY2015Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	143646000	USD
CY2016Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	141443000	USD
CY2014	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-2069000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	1238000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-918000	USD
CY2014	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	3655000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1238000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	918000	USD
CY2014	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-1967000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	667000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-495000	USD
CY2014	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	2000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	0	USD
CY2016	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	0	USD
CY2014	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	-1000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	0	USD
CY2016	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	0	USD
CY2014	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	1126000	USD
CY2015	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	0	USD
CY2016	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	0	USD
CY2014	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	664000	USD
CY2015	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	0	USD
CY2016	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	0	USD
CY2014	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	30418000	USD
CY2015	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	29526000	USD
CY2016	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	25501000	USD
CY2014	us-gaap	Other Income OtherIncome	1055000	USD
CY2015	us-gaap	Other Income OtherIncome	905000	USD
CY2016	us-gaap	Other Income OtherIncome	624000	USD
CY2015Q4	us-gaap	Other Inventory OtherInventory	4273000	USD
CY2016Q4	us-gaap	Other Inventory OtherInventory	4585000	USD
CY2015Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	73427000	USD
CY2016Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	70604000	USD
CY2015Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	130821000	USD
CY2016Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	153319000	USD
CY2014	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	11346000	USD
CY2015	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	9300000	USD
CY2016	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	10078000	USD
CY2014	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	1103000	USD
CY2015	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	-517000	USD
CY2016	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	5557000	USD
CY2014	us-gaap	Other Sales Revenue Net OtherSalesRevenueNet	39219000	USD
CY2015	us-gaap	Other Sales Revenue Net OtherSalesRevenueNet	28685000	USD
CY2016	us-gaap	Other Sales Revenue Net OtherSalesRevenueNet	23569000	USD
CY2014	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-2155000	USD
CY2015	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	3027000	USD
CY2016	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	7278000	USD
CY2014	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	79856000	USD
CY2015	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	2920000	USD
CY2016	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	0	USD
CY2014	us-gaap	Payments For Repurchase Of Redeemable Noncontrolling Interest PaymentsForRepurchaseOfRedeemableNoncontrollingInterest	20871000	USD
CY2015	us-gaap	Payments For Repurchase Of Redeemable Noncontrolling Interest PaymentsForRepurchaseOfRedeemableNoncontrollingInterest	0	USD
CY2016	us-gaap	Payments For Repurchase Of Redeemable Noncontrolling Interest PaymentsForRepurchaseOfRedeemableNoncontrollingInterest	0	USD
CY2000	us-gaap	Payments For Repurchase Of Trust Preferred Securities PaymentsForRepurchaseOfTrustPreferredSecurities	10000000	USD
CY2014	us-gaap	Payments Of Dividends PaymentsOfDividends	78314000	USD
CY2015	us-gaap	Payments Of Dividends PaymentsOfDividends	82397000	USD
CY2016	us-gaap	Payments Of Dividends PaymentsOfDividends	87154000	USD
CY2014	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	12267000	USD
CY2015	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	0	USD
CY2016	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	0	USD
CY2014Q3	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	4800000	USD
CY2015	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	95000	USD
CY2016	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	0	USD
CY2014	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	1072000	USD
CY2015	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	1944000	USD
CY2016	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	13097000	USD
CY2014	us-gaap	Payments To Acquire Notes Receivable PaymentsToAcquireNotesReceivable	1200000	USD
CY2015	us-gaap	Payments To Acquire Notes Receivable PaymentsToAcquireNotesReceivable	2307000	USD
CY2016	us-gaap	Payments To Acquire Notes Receivable PaymentsToAcquireNotesReceivable	10094000	USD
CY2014	us-gaap	Payments To Acquire Other Productive Assets PaymentsToAcquireOtherProductiveAssets	6427000	USD
CY2015	us-gaap	Payments To Acquire Other Productive Assets PaymentsToAcquireOtherProductiveAssets	885000	USD
CY2016	us-gaap	Payments To Acquire Other Productive Assets PaymentsToAcquireOtherProductiveAssets	353000	USD
CY2014	us-gaap	Payments To Acquire Other Property Plant And Equipment PaymentsToAcquireOtherPropertyPlantAndEquipment	325922000	USD
CY2015	us-gaap	Payments To Acquire Other Property Plant And Equipment PaymentsToAcquireOtherPropertyPlantAndEquipment	394310000	USD
CY2016	us-gaap	Payments To Acquire Other Property Plant And Equipment PaymentsToAcquireOtherPropertyPlantAndEquipment	406997000	USD
CY2014	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	325516000	USD
CY2015	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	393425000	USD
CY2016	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	406644000	USD
CY2014	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	54179000	USD
CY2015	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	0	USD
CY2016	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	0	USD
CY2014	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	22943000	USD
CY2015	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	37050000	USD
CY2016	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	38786000	USD
CY2015Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Current Liabilities PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities	10233000	USD
CY2016Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Current Liabilities PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities	10994000	USD
CY2015Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	201453000	USD
CY2016Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	226552000	USD
CY2014	us-gaap	Pension Contributions PensionContributions	32000000	USD
CY2015	us-gaap	Pension Contributions PensionContributions	12000000	USD
CY2016	us-gaap	Pension Contributions PensionContributions	12000000	USD
CY2016Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	10000000	shares
CY2015Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2016Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
	us-gaap	Proceeds From Divestiture Of Businesses ProceedsFromDivestitureOfBusinesses	143700000	USD
CY2014	us-gaap	Proceeds From Divestiture Of Businesses Net Of Cash Divested ProceedsFromDivestitureOfBusinessesNetOfCashDivested	229903000	USD
CY2015	us-gaap	Proceeds From Divestiture Of Businesses Net Of Cash Divested ProceedsFromDivestitureOfBusinessesNetOfCashDivested	13856000	USD
CY2016	us-gaap	Proceeds From Divestiture Of Businesses Net Of Cash Divested ProceedsFromDivestitureOfBusinessesNetOfCashDivested	0	USD
CY2014	us-gaap	Proceeds From Income Tax Refunds ProceedsFromIncomeTaxRefunds	35573000	USD
CY2015	us-gaap	Proceeds From Income Tax Refunds ProceedsFromIncomeTaxRefunds	37200000	USD
CY2016	us-gaap	Proceeds From Income Tax Refunds ProceedsFromIncomeTaxRefunds	18861000	USD
CY2014	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	4060000	USD
CY2015	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	1560000	USD
CY2016	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	66953000	USD
CY2014	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	150000000	USD
CY2015	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	100000000	USD
CY2016	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	245000000	USD
CY2014	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	7359000	USD
CY2015	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-11379000	USD
CY2016	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-4410000	USD
CY2014	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-66000000	USD
CY2015	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	0	USD
CY2016	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	15000000	USD
CY2014	us-gaap	Proceeds From Sale And Collection Of Notes Receivable ProceedsFromSaleAndCollectionOfNotesReceivable	0	USD
CY2015	us-gaap	Proceeds From Sale And Collection Of Notes Receivable ProceedsFromSaleAndCollectionOfNotesReceivable	0	USD
CY2016	us-gaap	Proceeds From Sale And Collection Of Notes Receivable ProceedsFromSaleAndCollectionOfNotesReceivable	5000000	USD
CY2014	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	14612000	USD
CY2015	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	0	USD
CY2016	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	0	USD
CY2014	us-gaap	Profit Loss ProfitLoss	192277000	USD
CY2015Q1	us-gaap	Profit Loss ProfitLoss	46462000	USD
CY2015Q2	us-gaap	Profit Loss ProfitLoss	25274000	USD
CY2015Q3	us-gaap	Profit Loss ProfitLoss	13043000	USD
CY2015Q4	us-gaap	Profit Loss ProfitLoss	38538000	USD
CY2015	us-gaap	Profit Loss ProfitLoss	123317000	USD
CY2016Q1	us-gaap	Profit Loss ProfitLoss	57665000	USD
CY2016Q2	us-gaap	Profit Loss ProfitLoss	27287000	USD
CY2016Q3	us-gaap	Profit Loss ProfitLoss	12261000	USD
CY2016Q4	us-gaap	Profit Loss ProfitLoss	40103000	USD
CY2016	us-gaap	Profit Loss ProfitLoss	137316000	USD
CY2015Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	5331875000	USD
CY2016Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	5656973000	USD
CY2014	us-gaap	Public Utilities Allowance For Funds Used During Construction Additions PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions	3924000	USD
CY2015	us-gaap	Public Utilities Allowance For Funds Used During Construction Additions PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions	3546000	USD
CY2016	us-gaap	Public Utilities Allowance For Funds Used During Construction Additions PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions	2651000	USD
CY2014	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	8808000	USD
CY2015	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	8331000	USD
CY2016	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	8475000	USD
CY2015Q4	us-gaap	Public Utilities Property Plant And Equipment Accumulated Depreciation PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation	1433286000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Accumulated Depreciation PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation	1509473000	USD
CY2015Q4	us-gaap	Public Utilities Property Plant And Equipment Construction Work In Progress PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress	202683000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Construction Work In Progress PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress	150474000	USD
CY2015Q4	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	3898589000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	4147500000	USD
CY2015Q4	us-gaap	Public Utilities Property Plant And Equipment Plant In Service PublicUtilitiesPropertyPlantAndEquipmentPlantInService	5129192000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Plant In Service PublicUtilitiesPropertyPlantAndEquipmentPlantInService	5506499000	USD
CY2014	us-gaap	Real Estate Tax Expense RealEstateTaxExpense	33932000	USD
CY2015	us-gaap	Real Estate Tax Expense RealEstateTaxExpense	35948000	USD
CY2016	us-gaap	Real Estate Tax Expense RealEstateTaxExpense	38505000	USD
CY2015Q4	us-gaap	Refundable Gas Costs RefundableGasCosts	17880000	USD
CY2015Q4	us-gaap	Refundable Gas Costs RefundableGasCosts	17900000	USD
CY2016Q4	us-gaap	Refundable Gas Costs RefundableGasCosts	30800000	USD
CY2016Q4	us-gaap	Refundable Gas Costs RefundableGasCosts	30820000	USD
CY2015Q4	us-gaap	Regulated Entity Other Assets Noncurrent RegulatedEntityOtherAssetsNoncurrent	558368000	USD
CY2016Q4	us-gaap	Regulated Entity Other Assets Noncurrent RegulatedEntityOtherAssetsNoncurrent	669471000	USD
CY2015Q4	us-gaap	Regulatory Assets RegulatoryAssets	579632000	USD
CY2016Q4	us-gaap	Regulatory Assets RegulatoryAssets	699828000	USD
CY2015Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	99798000	USD
CY2016Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	135751000	USD
CY2015Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	333883000	USD
CY2016Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	396952000	USD
CY2016Q4	us-gaap	Remaining Amounts Of Regulatory Assets For Which No Return On Investment During Recovery Period Is Provided RemainingAmountsOfRegulatoryAssetsForWhichNoReturnOnInvestmentDuringRecoveryPeriodIsProvided	301006000	USD
CY2014	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	46000000	USD
CY2015	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	0	USD
CY2016	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	0	USD
CY2014	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	39971000	USD
CY2015	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	2905000	USD
CY2016	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	163167000	USD
CY2014Q4	us-gaap	Stockholders Equity StockholdersEquity	1483242000	USD
CY2015Q4	us-gaap	Stockholders Equity StockholdersEquity	1528287000	USD
CY2016Q4	us-gaap	Stockholders Equity StockholdersEquity	1648476000	USD
CY2014Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1483671000	USD
CY2015Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1528626000	USD
CY2016Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1648727000	USD
CY2016Q4	us-gaap	Tax Credit Carryforward Amount TaxCreditCarryforwardAmount	17100000	USD
CY2014	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	31.57
CY2014	us-gaap	Repayments Of Other Debt RepaymentsOfOtherDebt	16407000	USD
CY2015	us-gaap	Repayments Of Other Debt RepaymentsOfOtherDebt	1431000	USD
CY2016	us-gaap	Repayments Of Other Debt RepaymentsOfOtherDebt	0	USD
CY2015Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	530940000	USD
CY2016Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	581014000	USD
CY2015Q4	us-gaap	Retained Earnings Appropriated RetainedEarningsAppropriated	21030000	USD
CY2016Q4	us-gaap	Retained Earnings Appropriated RetainedEarningsAppropriated	25564000	USD
CY2014	us-gaap	Revenues Revenues	1472562000	USD
CY2015Q1	us-gaap	Revenues Revenues	446490000	USD
CY2015Q2	us-gaap	Revenues Revenues	337332000	USD
CY2015Q3	us-gaap	Revenues Revenues	313649000	USD
CY2015Q4	us-gaap	Revenues Revenues	387305000	USD
CY2015	us-gaap	Revenues Revenues	1484776000	USD
CY2016Q1	us-gaap	Revenues Revenues	418173000	USD
CY2016Q2	us-gaap	Revenues Revenues	318838000	USD
CY2016Q3	us-gaap	Revenues Revenues	303349000	USD
CY2016Q4	us-gaap	Revenues Revenues	402123000	USD
CY2016	us-gaap	Revenues Revenues	1442483000	USD
CY2015Q4	us-gaap	Secured Debt SecuredDebt	1611700000	USD
CY2016Q4	us-gaap	Secured Debt SecuredDebt	1696700000	USD
CY2014	us-gaap	Share Based Compensation ShareBasedCompensation	8114000	USD
CY2015	us-gaap	Share Based Compensation ShareBasedCompensation	6914000	USD
CY2016	us-gaap	Share Based Compensation ShareBasedCompensation	7891000	USD
CY2016Q4	us-gaap	Statutory Accounting Practices Statutory Amount Available For Dividend Payments StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPayments	263400000	USD
CY2014	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	150119000	USD
CY2015	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	0	USD
CY2016	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	0	USD
CY2015	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	32.66
CY2015Q4	us-gaap	Unamortized Debt Issuance Expense UnamortizedDebtIssuanceExpense	10852000	USD
CY2016Q4	us-gaap	Unamortized Debt Issuance Expense UnamortizedDebtIssuanceExpense	10639000	USD
CY2015Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	62003000	USD
CY2016Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	72377000	USD
CY2014	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	0	USD
CY2015	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	0	USD
CY2016	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	0	USD
CY2016Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On Fifth Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary	125791000	USD
CY2016Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	62605000	shares
CY2016Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	63386000	shares
CY2016Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On First Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary	298043000	USD
CY2016Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On Fourth Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary	151218000	USD
CY2016Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On Second Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary	252310000	USD
CY2016Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On Third Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary	228145000	USD
CY2016Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance Sheet Amount UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount	2180523000	USD
CY2016Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Due After Five Years UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears	1125016000	USD
CY2014	us-gaap	Utilities Operating Expense Depreciation And Amortization UtilitiesOperatingExpenseDepreciationAndAmortization	129570000	USD
CY2015	us-gaap	Utilities Operating Expense Depreciation And Amortization UtilitiesOperatingExpenseDepreciationAndAmortization	143499000	USD
CY2016	us-gaap	Utilities Operating Expense Depreciation And Amortization UtilitiesOperatingExpenseDepreciationAndAmortization	160514000	USD
CY2014	us-gaap	Utilities Operating Expense Maintenance Operations And Other Costs And Expenses UtilitiesOperatingExpenseMaintenanceOperationsAndOtherCostsAndExpenses	286832000	USD
CY2015	us-gaap	Utilities Operating Expense Maintenance Operations And Other Costs And Expenses UtilitiesOperatingExpenseMaintenanceOperationsAndOtherCostsAndExpenses	303221000	USD
CY2016	us-gaap	Utilities Operating Expense Maintenance Operations And Other Costs And Expenses UtilitiesOperatingExpenseMaintenanceOperationsAndOtherCostsAndExpenses	315795000	USD
CY2014	us-gaap	Utilities Operating Expense Products And Services UtilitiesOperatingExpenseProductsAndServices	678244000	USD
CY2015	us-gaap	Utilities Operating Expense Products And Services UtilitiesOperatingExpenseProductsAndServices	656964000	USD
CY2016	us-gaap	Utilities Operating Expense Products And Services UtilitiesOperatingExpenseProductsAndServices	551366000	USD
CY2014	us-gaap	Utilities Operating Expense Taxes UtilitiesOperatingExpenseTaxes	94300000	USD
CY2015	us-gaap	Utilities Operating Expense Taxes UtilitiesOperatingExpenseTaxes	97657000	USD
CY2016	us-gaap	Utilities Operating Expense Taxes UtilitiesOperatingExpenseTaxes	98735000	USD
CY2014	us-gaap	Utility Revenue UtilityRevenue	1433343000	USD
CY2015	us-gaap	Utility Revenue UtilityRevenue	1456091000	USD
CY2016	us-gaap	Utility Revenue UtilityRevenue	1418914000	USD
CY2014	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	5296000	USD
CY2015	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	5802000	USD
CY2016	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	6053000	USD
CY2014	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	44717000	USD
CY2015	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	6160000	USD
CY2016	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	5557000	USD
CY2014	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	61887000	shares
CY2015Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	62889000	shares
CY2015Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	62600000	shares
CY2015Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	62688000	shares
CY2015Q4	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	62758000	shares
CY2015	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	62708000	shares
CY2016Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	62907000	shares
CY2016Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	63783000	shares
CY2016Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	64325000	shares
CY2016Q4	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	64620000	shares
CY2016	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	63920000	shares
CY2014	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	61632000	shares
CY2015Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	62318000	shares
CY2015Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	62281000	shares
CY2015Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	62299000	shares
CY2015Q4	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	62308000	shares
CY2015	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	62301000	shares
CY2016Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	63857000	shares
CY2016Q4	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	64185000	shares
CY2016	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	63508000	shares
CY2016	us-gaap	Derivatives Reporting Of Derivative Activity DerivativesReportingOfDerivativeActivity	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:12px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-style:italic;font-weight:bold;">Derivative Assets and Liabilities</font></div><div style="line-height:120%;padding-top:6px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Derivatives are recorded as either assets or liabilities on the Consolidated Balance Sheets measured at estimated fair value.</font></div><div style="line-height:120%;padding-top:8px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">The UTC and the IPUC issued accounting orders authorizing Avista Corp. to offset energy commodity derivative assets or liabilities with a regulatory asset or liability. This accounting treatment is intended to defer the recognition of mark-to-market gains and losses on energy commodity transactions until the period of delivery. Realized benefits and costs result in adjustments to retail rates through PGAs, the ERM in Washington, the PCA mechanism in Idaho, and periodic general rates cases. The resulting regulatory assets have been concluded to be probable of recovery through future rates.</font></div><div style="line-height:120%;padding-top:12px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Substantially all forward contracts to purchase or sell power and natural gas are recorded as derivative assets or liabilities at estimated fair value with an offsetting regulatory asset or liability. Contracts that are not considered derivatives are accounted for on the accrual basis until they are settled or realized unless there is a decline in the fair value of the contract that is determined to be other-than-temporary.</font></div><div style="line-height:120%;padding-top:8px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">For interest rate swap derivatives, Avista Corp. records all mark-to-market gains and losses in each accounting period as assets and liabilities, as well as offsetting regulatory assets and liabilities, such that there is no income statement impact. The interest rate swap derivatives are risk management tools similar to energy commodity derivatives. Upon settlement of interest rate swap derivatives, the regulatory asset or liability is amortized as a component of interest expense over the term of the associated debt. The Company records an offset of interest rate swap derivative assets and liabilities with regulatory assets and liabilities, based on the prior practice of the commissions to provide recovery through the ratemaking process.</font></div><div style="line-height:120%;padding-top:12px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">As of </font><font style="font-family:inherit;font-size:10pt;">December 31, 2016</font><font style="font-family:inherit;font-size:10pt;">, the Company has multiple master netting agreements with a variety of entities that allow for cross-commodity netting of derivative agreements with the same counterparty (i.e. power derivatives can be netted with natural gas derivatives). In addition, some master netting agreements allow for the netting of commodity derivatives and interest rate swap derivatives for the same counterparty. The Company does not have any agreements which allow for cross-affiliate netting among multiple affiliated legal entities. The Company nets all derivative instruments when allowed by the agreement for presentation in the Consolidated Balance Sheets.</font></div></div>
CY2016	us-gaap	Nature Of Operations NatureOfOperations	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:6px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-style:italic;font-weight:bold;">Nature of Business</font></div><div style="line-height:120%;padding-top:6px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Avista Corp. is primarily an electric and natural gas utility with certain other business ventures. Avista Utilities is an operating division of Avista Corp., comprising the regulated utility operations in the Pacific Northwest. Avista Utilities provides electric distribution and transmission, and natural gas distribution services in parts of eastern Washington and northern Idaho. Avista Utilities also provides natural gas distribution service in parts of northeastern and southwestern Oregon. Avista Utilities has electric generating facilities in Washington, Idaho, Oregon and Montana. Avista Utilities also supplies electricity to a small number of customers in Montana, most of whom are employees who operate Avista Utilities' Noxon Rapids generating facility.</font></div><div style="line-height:120%;padding-top:6px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">AERC is a wholly-owned subsidiary of Avista Corp. The primary subsidiary of AERC is AEL&P, which comprises Avista Corp.'s regulated utility operations in Alaska. AERC was acquired by Avista Corp. on July 1, 2014 and there are no AERC earnings included in the overall results of Avista Corp. prior to that date. See Note 4 for information regarding the acquisition of AERC.</font></div><div style="line-height:120%;padding-top:6px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Avista Capital, a wholly owned non-regulated subsidiary of Avista Corp., is the parent company of all of the subsidiary companies in the non-utility businesses, with the exception of AJT Mining Properties, which is a subsidiary of AERC. During the first half of 2014 and prior, Avista Capital’s subsidiaries included Ecova, which was an </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">80.2 percent</font><font style="font-family:inherit;font-size:10pt;"> owned subsidiary prior to its disposition on June 30, 2014. See Note 5 for information regarding the disposition of Ecova and Note 21 for business segment information.</font></div><div style="line-height:120%;padding-top:12px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-style:italic;font-weight:bold;"></font></div></div>
CY2016	us-gaap	Use Of Estimates UseOfEstimates	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:12px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-style:italic;font-weight:bold;">Use of Estimates</font></div><div style="line-height:120%;padding-top:6px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported for assets and liabilities and the 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. Significant estimates include:</font></div><table cellpadding="0" cellspacing="0" style="padding-top:8px;font-family:Times New Roman; font-size:10pt;"><tr><td style="width:96px;" rowspan="1" colspan="1"></td><td rowspan="1" colspan="1"></td></tr><tr><td style="vertical-align:top" rowspan="1" colspan="1"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><font style="font-family:inherit;font-size:10pt;">•</font></div></td><td style="vertical-align:top;" rowspan="1" colspan="1"><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">determining the market value of energy commodity derivative assets and liabilities,</font></div></td></tr></table><table cellpadding="0" cellspacing="0" style="padding-top:8px;font-family:Times New Roman; font-size:10pt;"><tr><td style="width:96px;" rowspan="1" colspan="1"></td><td rowspan="1" colspan="1"></td></tr><tr><td style="vertical-align:top" rowspan="1" colspan="1"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><font style="font-family:inherit;font-size:10pt;">•</font></div></td><td style="vertical-align:top;" rowspan="1" colspan="1"><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">pension and other postretirement benefit plan obligations,</font></div></td></tr></table><table cellpadding="0" cellspacing="0" style="padding-top:8px;font-family:Times New Roman; font-size:10pt;"><tr><td style="width:96px;" rowspan="1" colspan="1"></td><td rowspan="1" colspan="1"></td></tr><tr><td style="vertical-align:top" rowspan="1" colspan="1"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><font style="font-family:inherit;font-size:10pt;">•</font></div></td><td style="vertical-align:top;" rowspan="1" colspan="1"><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">contingent liabilities,</font></div></td></tr></table><table cellpadding="0" cellspacing="0" style="padding-top:8px;font-family:Times New Roman; font-size:10pt;"><tr><td style="width:96px;" rowspan="1" colspan="1"></td><td rowspan="1" colspan="1"></td></tr><tr><td style="vertical-align:top" rowspan="1" colspan="1"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><font style="font-family:inherit;font-size:10pt;">•</font></div></td><td style="vertical-align:top;" rowspan="1" colspan="1"><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">goodwill impairment testing,</font></div></td></tr></table><table cellpadding="0" cellspacing="0" style="padding-top:8px;font-family:Times New Roman; font-size:10pt;"><tr><td style="width:96px;" rowspan="1" colspan="1"></td><td rowspan="1" colspan="1"></td></tr><tr><td style="vertical-align:top" rowspan="1" colspan="1"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><font style="font-family:inherit;font-size:10pt;">•</font></div></td><td style="vertical-align:top;" rowspan="1" colspan="1"><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">recoverability of regulatory assets, and</font></div></td></tr></table><table cellpadding="0" cellspacing="0" style="padding-top:8px;font-family:Times New Roman; font-size:10pt;"><tr><td style="width:96px;" rowspan="1" colspan="1"></td><td rowspan="1" colspan="1"></td></tr><tr><td style="vertical-align:top" rowspan="1" colspan="1"><div style="line-height:120%;font-size:10pt;padding-left:48px;"><font style="font-family:inherit;font-size:10pt;">•</font></div></td><td style="vertical-align:top;" rowspan="1" colspan="1"><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">unbilled revenues.</font></div></td></tr></table><div style="line-height:120%;padding-top:12px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Changes in these estimates and assumptions are considered reasonably possible and may have a material effect on the consolidated financial statements and thus actual results could differ from the amounts reported and disclosed herein.</font></div></div>

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$AVA
AVISTA CORP Stock $ava

2016 Form 10-K Financial Statement

#000010491817000053 Filed on February 22, 2017

Income Statement

Balance Sheet

Cashflow Statement

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$AVA AVISTA CORP Stock $ava

2016 Form 10-K Financial Statement

#000010491817000053 Filed on February 22, 2017

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$AVA
AVISTA CORP Stock $ava