$IDA
IDACORP INC Stock $ida

$ida Overview Financials Valuation SEC Filings Company Website

2017 Form 10-K Financial Statement

#000105787718000027 Filed on February 22, 2018

Income Statement

Concept	2017	2016 Q4	2016
Revenue	$1.349B	$293.6M	$1.262B
YoY Change	6.93%	2.87%	-0.65%
Cost Of Revenue	$249.0M	$74.90M	$246.4M
YoY Change	1.06%	20.61%	8.45%
Gross Profit	$1.101B	$218.7M	$1.016B
YoY Change	8.36%	-2.06%	-2.64%
Gross Profit Margin	81.55%	74.49%	80.47%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$165.9M	$37.10M	$147.3M
YoY Change	12.65%	2.2%	3.31%
% of Gross Profit	15.08%	16.96%	14.5%
Operating Expenses	$1.034B	$154.7M	$978.4M
YoY Change	5.67%	-7.03%	-0.99%
Operating Profit	$315.5M	$64.00M	$283.6M
YoY Change	11.27%	12.48%	0.53%
Interest Expense	$83.75M	-$22.90M	$82.04M
YoY Change	2.09%	-20.76%	0.12%
% of Operating Profit	26.54%	-35.78%	28.93%
Other Income/Expense, Net	$12.55M	-$200.0K	$15.86M
YoY Change	-20.88%	-101.96%	-38.78%
Pretax Income	$261.8M	$41.00M	$234.5M
YoY Change	11.65%	7.33%	-2.38%
Income Tax	$48.66M	$7.800M	$36.43M
% Of Pretax Income	18.58%	19.02%	15.53%
Net Earnings	$212.4M	$33.20M	$198.3M
YoY Change	7.13%	4.4%	1.85%
Net Earnings / Revenue	15.74%	11.31%	15.71%
Basic Earnings Per Share	$4.22		$3.94
Diluted Earnings Per Share	$4.21	$658.7K	$3.94
COMMON SHARES
Basic Shares Outstanding	50.36M shares	50.40M shares	50.30M shares
Diluted Shares Outstanding	50.42M shares		50.37M shares

Balance Sheet

Concept	2017	2016 Q4	2016
SHORT-TERM ASSETS
Cash & Short-Term Investments	$76.60M	$61.50M	$61.50M
YoY Change	24.55%	-46.43%	-46.43%
Cash & Equivalents	$76.60M	$61.48M	$61.50M
Short-Term Investments
Other Short-Term Assets	$140.8M	$5.961M	$167.7M
YoY Change	-16.04%	1969.79%	25.81%
Inventory	$112.4M	$111.6M	$111.6M
Prepaid Expenses		$18.39M
Receivables	$75.20M	$71.56M	$71.60M
Other Receivables	$38.60M	$28.00M	$28.00M
Total Short-Term Assets	$443.6M	$440.3M	$440.3M
YoY Change	0.75%	-4.7%	-4.7%
LONG-TERM ASSETS
Property, Plant & Equipment	$4.284B	$4.172B	$4.172B
YoY Change	2.68%	4.5%	4.5%
Goodwill
YoY Change
Intangibles
YoY Change
Long-Term Investments	$115.7M	$11.21M	$125.2M
YoY Change	-7.59%	0.81%	-11.02%
Other Assets	$1.198B	$62.06M	$1.520B
YoY Change	-21.16%	54.31%	9.0%
Total Long-Term Assets	$5.602B	$5.850B	$5.850B
YoY Change	-4.24%	5.18%	5.18%
TOTAL ASSETS
Total Short-Term Assets	$443.6M	$440.3M	$440.3M
Total Long-Term Assets	$5.602B	$5.850B	$5.850B
Total Assets	$6.045B	$6.290B	$6.290B
YoY Change	-3.89%	4.43%	4.43%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$90.30M	$106.2M	$106.2M
YoY Change	-14.97%	11.17%	11.2%
Accrued Expenses	$69.40M	$68.20M	$68.20M
YoY Change	1.76%	4.44%	4.44%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$21.80M	$21.80M
YoY Change	-100.0%	9.0%	9.0%
Long-Term Debt Due	$0.00	$1.064M	$1.100M
YoY Change	-100.0%	0.0%	0.0%
Total Short-Term Liabilities	$200.7M	$249.7M	$249.7M
YoY Change	-19.62%	3.06%	3.05%
LONG-TERM LIABILITIES
Long-Term Debt	$1.746B	$1.745B	$1.745B
YoY Change	0.09%	1.11%	1.11%
Other Long-Term Liabilities	$1.182B	$45.08M	$893.5M
YoY Change	32.23%	-1.71%	4.36%
Total Long-Term Liabilities	$2.928B	$2.138B	$2.638B
YoY Change	10.97%	7.23%	2.19%
TOTAL LIABILITIES
Total Short-Term Liabilities	$200.7M	$249.7M	$249.7M
Total Long-Term Liabilities	$2.928B	$2.138B	$2.638B
Total Liabilities	$3.794B	$2.387B	$4.136B
YoY Change	-8.27%	6.78%	4.3%
SHAREHOLDERS EQUITY
Retained Earnings		$1.323B
YoY Change		7.57%
Common Stock		$851.8M
YoY Change		0.32%
Preferred Stock
YoY Change
Treasury Stock (at cost)		$243.0K
YoY Change		326.32%
Treasury Stock Shares		23.24K shares
Shareholders Equity	$2.251B	$2.154B	$2.154B
YoY Change
Total Liabilities & Shareholders Equity	$6.045B	$6.290B	$6.290B
YoY Change	-3.89%	4.43%	4.43%

Cashflow Statement

Concept	2017	2016 Q4	2016
OPERATING ACTIVITIES
Net Income	$212.4M	$33.20M	$198.3M
YoY Change	7.13%	4.4%	1.85%
Depreciation, Depletion And Amortization	$165.9M	$37.10M	$147.3M
YoY Change	12.65%	2.2%	3.31%
Cash From Operating Activities	$435.2M	$68.80M	$344.2M
YoY Change	26.43%	10.26%	-2.55%
INVESTING ACTIVITIES
Capital Expenditures	$285.5M	-$97.00M	$297.0M
YoY Change	-3.86%	66.95%	1.0%
Acquisitions
YoY Change
Other Investing Activities	-$5.340M	$600.0K	-$4.655M
YoY Change	14.72%	-185.71%	481.15%
Cash From Investing Activities	-$280.4M	-$96.40M	-$293.9M
YoY Change	-4.59%	63.95%	0.76%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net	$3.212M		$3.329M
YoY Change	-3.51%		1.59%
Debt Paid & Issued, Net	$1.064M		$101.1M
YoY Change	-98.95%		-16.52%
Cash From Financing Activities	-$139.6M	-11.70M	-$103.6M
YoY Change	34.72%	17.0%	2864.63%
NET CHANGE
Cash From Operating Activities	$435.2M	68.80M	$344.2M
Cash From Investing Activities	-$280.4M	-96.40M	-$293.9M
Cash From Financing Activities	-$139.6M	-11.70M	-$103.6M
Net Change In Cash	$15.17M	-39.30M	-$53.32M
YoY Change	-128.45%	514.06%	-191.94%
FREE CASH FLOW
Cash From Operating Activities	$435.2M	$68.80M	$344.2M
Capital Expenditures	$285.5M	-$97.00M	$297.0M
Free Cash Flow	$149.7M	$165.8M	$47.25M
YoY Change	216.8%	37.59%	-20.16%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2017	dei	Amendment Flag AmendmentFlag	false
CY2017	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2017	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2017	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2017
CY2017	dei	Document Period End Date DocumentPeriodEndDate	2017-12-31
CY2017	dei	Document Type DocumentType	10-K
CY2017	dei	Entity Central Index Key EntityCentralIndexKey	0001057877
CY2018Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	50392360	shares
CY2017	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2017	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2017Q2	dei	Entity Public Float EntityPublicFloat	4258357592	USD
CY2017	dei	Entity Registrant Name EntityRegistrantName	IDACORP INC.
CY2017	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	820505802
CY2017	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2017	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2017	dei	Trading Symbol TradingSymbol	IDA
CY2016Q4	ida	American Falls Bond Guarantee AmericanFallsBondGuarantee	19885000	USD
CY2017Q4	ida	American Falls Bond Guarantee AmericanFallsBondGuarantee	19885000	USD
CY2015	ida	Cumulativeeffectofaccountingchange Cumulativeeffectofaccountingchange	0	USD
CY2016	ida	Cumulativeeffectofaccountingchange Cumulativeeffectofaccountingchange	0	USD
CY2017	ida	Cumulativeeffectofaccountingchange Cumulativeeffectofaccountingchange	-4092000	USD
CY2015	ida	Deferred Investment Tax Credit DeferredInvestmentTaxCredit	3455000	USD
CY2016	ida	Deferred Investment Tax Credit DeferredInvestmentTaxCredit	3227000	USD
CY2017	ida	Deferred Investment Tax Credit DeferredInvestmentTaxCredit	10506000	USD
CY2016Q4	ida	Deferred Tax Liabilities Prepaid Pension Cost DeferredTaxLiabilitiesPrepaidPensionCost	140083000	USD
CY2017Q4	ida	Deferred Tax Liabilities Prepaid Pension Cost DeferredTaxLiabilitiesPrepaidPensionCost	103407000	USD
CY2015	ida	Effective Income Tax Rate Reconciliation Affordable Housing Investment Amortization EffectiveIncomeTaxRateReconciliationAffordableHousingInvestmentAmortization	1519000	USD
CY2016	ida	Effective Income Tax Rate Reconciliation Affordable Housing Investment Amortization EffectiveIncomeTaxRateReconciliationAffordableHousingInvestmentAmortization	1380000	USD
CY2017	ida	Effective Income Tax Rate Reconciliation Affordable Housing Investment Amortization EffectiveIncomeTaxRateReconciliationAffordableHousingInvestmentAmortization	1271000	USD
CY2015	ida	Effective Income Tax Rate Reconciliation Affordable Housing Investment Distribution EffectiveIncomeTaxRateReconciliationAffordableHousingInvestmentDistribution	0	USD
CY2016	ida	Effective Income Tax Rate Reconciliation Affordable Housing Investment Distribution EffectiveIncomeTaxRateReconciliationAffordableHousingInvestmentDistribution	-1717000	USD
CY2017	ida	Effective Income Tax Rate Reconciliation Affordable Housing Investment Distribution EffectiveIncomeTaxRateReconciliationAffordableHousingInvestmentDistribution	-1124000	USD
CY2015	ida	Effective Income Tax Rate Reconciliation Removal Costs EffectiveIncomeTaxRateReconciliationRemovalCosts	-4807000	USD
CY2016	ida	Effective Income Tax Rate Reconciliation Removal Costs EffectiveIncomeTaxRateReconciliationRemovalCosts	-5559000	USD
CY2017	ida	Effective Income Tax Rate Reconciliation Removal Costs EffectiveIncomeTaxRateReconciliationRemovalCosts	-6280000	USD
CY2015	ida	Effective Income Tax Rate Reconciliation Share Based Compensation EffectiveIncomeTaxRateReconciliationShareBasedCompensation	0	USD
CY2016	ida	Effective Income Tax Rate Reconciliation Share Based Compensation EffectiveIncomeTaxRateReconciliationShareBasedCompensation	1614000	USD
CY2017	ida	Effective Income Tax Rate Reconciliation Share Based Compensation EffectiveIncomeTaxRateReconciliationShareBasedCompensation	1508000	USD
CY2015	ida	Energy Efficiency Programs EnergyEfficiencyPrograms	30532000	USD
CY2016	ida	Energy Efficiency Programs EnergyEfficiencyPrograms	33754000	USD
CY2017	ida	Energy Efficiency Programs EnergyEfficiencyPrograms	39241000	USD
CY2017	ida	Extension Period Of Credit Agreements ExtensionPeriodOfCreditAgreements	P1Y
CY2016	ida	Fair Value All Levels Transfers Amount FairValueAllLevelsTransfersAmount	0	USD
CY2017	ida	Fair Value All Levels Transfers Amount FairValueAllLevelsTransfersAmount	0	USD
CY2015	ida	Impairment Of Receivables ImpairmentOfReceivables	0	USD
CY2016	ida	Impairment Of Receivables ImpairmentOfReceivables	0	USD
CY2017	ida	Impairment Of Receivables ImpairmentOfReceivables	0	USD
CY2015	ida	Income Tax Reconciliation Afudc IncomeTaxReconciliationAfudc	-11140000	USD
CY2016	ida	Income Tax Reconciliation Afudc IncomeTaxReconciliationAfudc	-11278000	USD
CY2017	ida	Income Tax Reconciliation Afudc IncomeTaxReconciliationAfudc	-10318000	USD
CY2015	ida	Income Tax Reconciliation Capitalized Interest IncomeTaxReconciliationCapitalizedInterest	2693000	USD
CY2016	ida	Income Tax Reconciliation Capitalized Interest IncomeTaxReconciliationCapitalizedInterest	2000000	USD
CY2017	ida	Income Tax Reconciliation Capitalized Interest IncomeTaxReconciliationCapitalizedInterest	1513000	USD
CY2015	ida	Income Tax Reconciliation Capitalized Overhead Costs IncomeTaxReconciliationCapitalizedOverheadCosts	-8750000	USD
CY2016	ida	Income Tax Reconciliation Capitalized Overhead Costs IncomeTaxReconciliationCapitalizedOverheadCosts	-10500000	USD
CY2017	ida	Income Tax Reconciliation Capitalized Overhead Costs IncomeTaxReconciliationCapitalizedOverheadCosts	-11200000	USD
CY2015	ida	Income Tax Reconciliation Capitalized Repair Costs IncomeTaxReconciliationCapitalizedRepairCosts	-28700000	USD
CY2016	ida	Income Tax Reconciliation Capitalized Repair Costs IncomeTaxReconciliationCapitalizedRepairCosts	-28000000	USD
CY2017	ida	Income Tax Reconciliation Capitalized Repair Costs IncomeTaxReconciliationCapitalizedRepairCosts	-28700000	USD
CY2017Q4	ida	Investment Tax Credit Percent InvestmentTaxCreditPercent	0.03
CY2017Q4	ida	Late Payment Fee Customer Billings LatePaymentFeeCustomerBillings	0.01
CY2017	ida	Latest Practicable Date LatestPracticableDate	2018-02-16
CY2015	ida	Maturity Period Of Short Term Investments MaturityPeriodOfShortTermInvestments	P90D
CY2016	ida	Maturity Period Of Short Term Investments MaturityPeriodOfShortTermInvestments	P90D
CY2017	ida	Maturity Period Of Short Term Investments MaturityPeriodOfShortTermInvestments	P90D
CY2016Q4	ida	Milner Dam Note Guarantee MilnerDamNoteGuarantee	1064000	USD
CY2017Q4	ida	Milner Dam Note Guarantee MilnerDamNoteGuarantee	0	USD
CY2016Q4	ida	Number Of Extensions Of Credit Agreement NumberOfExtensionsOfCreditAgreement	2	Y
CY2015	ida	Other Electric Utility Revenue OtherElectricUtilityRevenue	85580000	USD
CY2016	ida	Other Electric Utility Revenue OtherElectricUtilityRevenue	88155000	USD
CY2017	ida	Other Electric Utility Revenue OtherElectricUtilityRevenue	105535000	USD
CY2015	ida	Paymentsreceivedfromtransmissionprojectjointfundingpartners Paymentsreceivedfromtransmissionprojectjointfundingpartners	11377000	USD
CY2016	ida	Paymentsreceivedfromtransmissionprojectjointfundingpartners Paymentsreceivedfromtransmissionprojectjointfundingpartners	7586000	USD
CY2017	ida	Paymentsreceivedfromtransmissionprojectjointfundingpartners Paymentsreceivedfromtransmissionprojectjointfundingpartners	6074000	USD
CY2015	ida	Period Of Time After Which Unpaid Accounts Are Deemed Late PeriodOfTimeAfterWhichUnpaidAccountsAreDeemedLate	P30D
CY2016	ida	Period Of Time After Which Unpaid Accounts Are Deemed Late PeriodOfTimeAfterWhichUnpaidAccountsAreDeemedLate	P30D
CY2017	ida	Period Of Time After Which Unpaid Accounts Are Deemed Late PeriodOfTimeAfterWhichUnpaidAccountsAreDeemedLate	P30D
CY2017	ida	Period Over Which Bond Allocations Are To Cover Benefit Payments PeriodOverWhichBondAllocationsAreToCoverBenefitPayments	P5Y
CY2017	ida	Period Over Which Current Rate Of Return Is Lower Than Historical PeriodOverWhichCurrentRateOfReturnIsLowerThanHistorical	P20Y
CY2016Q4	ida	Pollution Control Revenue Bonds Variable Rate Series2000 Due2027 PollutionControlRevenueBondsVariableRateSeries2000Due2027	4360000	USD
CY2017Q4	ida	Pollution Control Revenue Bonds Variable Rate Series2000 Due2027 PollutionControlRevenueBondsVariableRateSeries2000Due2027	4360000	USD
CY2015	ida	Power Cost Adjustment PowerCostAdjustment	16766000	USD
CY2016	ida	Power Cost Adjustment PowerCostAdjustment	-5330000	USD
CY2017	ida	Power Cost Adjustment PowerCostAdjustment	52024000	USD
CY2015	ida	Restored Investment Tax Credit RestoredInvestmentTaxCredit	2963000	USD
CY2016	ida	Restored Investment Tax Credit RestoredInvestmentTaxCredit	2922000	USD
CY2017	ida	Restored Investment Tax Credit RestoredInvestmentTaxCredit	3081000	USD
CY2016Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	106194000	USD
CY2017Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	90277000	USD
CY2016Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	71557000	USD
CY2017Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	75249000	USD
CY2016Q4	us-gaap	Accounts Receivable Net Noncurrent AccountsReceivableNetNoncurrent	23482000	USD
CY2017Q4	us-gaap	Accounts Receivable Net Noncurrent AccountsReceivableNetNoncurrent	4307000	USD
CY2014Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-24158000	USD
CY2015Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-21276000	USD
CY2016Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-20882000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-30964000	USD
CY2017Q4	us-gaap	Additional Collateral Aggregate Fair Value AdditionalCollateralAggregateFairValue	4500000	USD
CY2016Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	968000	USD
CY2017Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	2013000	USD
CY2016Q4	us-gaap	Allowance For Doubtful Accounts Receivable Noncurrent AllowanceForDoubtfulAccountsReceivableNoncurrent	402000	USD
CY2017Q4	us-gaap	Allowance For Doubtful Accounts Receivable Noncurrent AllowanceForDoubtfulAccountsReceivableNoncurrent	402000	USD
CY2016Q4	us-gaap	Allowance For Doubtful Other Receivables Current AllowanceForDoubtfulOtherReceivablesCurrent	164000	USD
CY2017Q4	us-gaap	Allowance For Doubtful Other Receivables Current AllowanceForDoubtfulOtherReceivablesCurrent	180000	USD
CY2015Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	26153000	USD
CY2016Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	26257000	USD
CY2017Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	26415000	USD
CY2016	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	1031000	USD
CY2017	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	1015000	USD
CY2016	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	2686000	USD
CY2017	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	66000	USD
CY2016	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	1759000	USD
CY2017	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	-791000	USD
CY2015Q4	us-gaap	Assets Assets	6023314000	USD
CY2016Q4	us-gaap	Assets Assets	6289897000	USD
CY2017Q4	us-gaap	Assets Assets	6045405000	USD
CY2016Q4	us-gaap	Assets Current AssetsCurrent	440312000	USD
CY2017Q4	us-gaap	Assets Current AssetsCurrent	443601000	USD
CY2016Q4	us-gaap	Assets Noncurrent Other Than Noncurrent Investments And Property Plant And Equipment AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment	1552422000	USD
CY2017Q4	us-gaap	Assets Noncurrent Other Than Noncurrent Investments And Property Plant And Equipment AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment	1202231000	USD
CY2016Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	23908000	USD
CY2017Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	30249000	USD
CY2015	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	23840000	USD
CY2016	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	34603000	USD
CY2017	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	33220000	USD
CY2014Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	56808000	USD
CY2015Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	114802000	USD
CY2016Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	61480000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	76649000	USD
CY2016Q4	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	15000000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	28038000	USD
CY2015	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	57994000	USD
CY2016	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-53322000	USD
CY2017	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	15169000	USD
CY2017Q4	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	900000	USD
CY2016Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2017Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2015	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.76
CY2016	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.92
CY2017	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.08
CY2016Q4	us-gaap	Common Stock No Par Value CommonStockNoParValue
CY2017Q4	us-gaap	Common Stock No Par Value CommonStockNoParValue
CY2016Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	120000000	shares
CY2017Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	120000000	shares
CY2014Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	50308702	shares
CY2015Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	50352051	shares
CY2016Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	50420017	shares
CY2017Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	50420017	shares
CY2016Q4	us-gaap	Common Stock Value CommonStockValue	851833000	USD
CY2017Q4	us-gaap	Common Stock Value CommonStockValue	857207000	USD
CY2015	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	197561000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	198682000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	206429000	USD
CY2015	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	-204000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	-200000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	769000	USD
CY2015	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	197357000	USD
CY2016	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	198482000	USD
CY2017	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	207198000	USD
CY2015	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	4831000	USD
CY2016	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	1181000	USD
CY2017	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	11726000	USD
CY2015	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	7535000	USD
CY2016	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	3339000	USD
CY2017	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	17144000	USD
CY2015	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	2704000	USD
CY2016	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	2158000	USD
CY2017	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	5418000	USD
CY2016Q4	us-gaap	Customer Advances For Construction CustomerAdvancesForConstruction	21438000	USD
CY2017Q4	us-gaap	Customer Advances For Construction CustomerAdvancesForConstruction	18414000	USD
CY2015	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	34770000	USD
CY2016	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	33205000	USD
CY2017	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	24018000	USD
CY2015	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	35396000	USD
CY2016	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	33305000	USD
CY2017	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	23864000	USD
CY2016Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	1658353000	USD
CY2017Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	1028178000	USD
CY2015	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	38645000	USD
CY2016	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	35732000	USD
CY2017	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	33245000	USD
CY2015	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	626000	USD
CY2016	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	100000	USD
CY2017	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-154000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Equity Method Investments DeferredTaxAssetsEquityMethodInvestments	6543000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Equity Method Investments DeferredTaxAssetsEquityMethodInvestments	3540000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	414103000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	367238000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	11401000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	8636000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Regulatory Assets And Liabilities DeferredTaxAssetsRegulatoryAssetsAndLiabilities	51326000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Regulatory Assets And Liabilities DeferredTaxAssetsRegulatoryAssetsAndLiabilities	98744000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards DeferredTaxAssetsTaxCreditCarryforwards	142627000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards DeferredTaxAssetsTaxCreditCarryforwards	109673000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Pensions DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions	132362000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Pensions DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions	94493000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	29490000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	21066000	USD
CY2016Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Other DeferredTaxAssetsTaxDeferredExpenseOther	40354000	USD
CY2017Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Other DeferredTaxAssetsTaxDeferredExpenseOther	31086000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	1244250000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	660940000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Investment In Noncontrolled Affiliates DeferredTaxLiabilitiesInvestmentInNoncontrolledAffiliates	12371000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Investment In Noncontrolled Affiliates DeferredTaxLiabilitiesInvestmentInNoncontrolledAffiliates	5182000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	1244250000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	660940000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	17919000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	21242000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	500987000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	306002000	USD
CY2016Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets And Liabilities DeferredTaxLiabilitiesRegulatoryAssetsAndLiabilities	948540000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets And Liabilities DeferredTaxLiabilitiesRegulatoryAssetsAndLiabilities	584329000	USD
CY2015	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	7000000	USD
CY2016	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	8000000	USD
CY2017	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	7000000	USD
CY2015	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	142581000	USD
CY2016	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	147294000	USD
CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	165933000	USD
CY2016Q4	us-gaap	Derivative Asset Collateral Obligation To Return Cash Offset DerivativeAssetCollateralObligationToReturnCashOffset	1900000	USD
CY2016Q4	us-gaap	Derivative Asset Fair Value Gross Liability DerivativeAssetFairValueGrossLiability	2183000	USD
CY2017Q4	us-gaap	Derivative Asset Fair Value Gross Liability DerivativeAssetFairValueGrossLiability	553000	USD
CY2016Q4	us-gaap	Derivative Assets DerivativeAssets	5951000	USD
CY2017Q4	us-gaap	Derivative Assets DerivativeAssets	22000	USD
CY2016Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	8134000	USD
CY2017Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	575000	USD
CY2016Q4	us-gaap	Derivative Fair Value Of Derivative Asset Amount Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral	5951000	USD
CY2017Q4	us-gaap	Derivative Fair Value Of Derivative Asset Amount Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral	22000	USD
CY2016Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	302000	USD
CY2017Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	1973000	USD
CY2016Q4	us-gaap	Derivative Fair Value Of Derivative Liability Amount Offset Against Collateral DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral	0	USD
CY2017Q4	us-gaap	Derivative Fair Value Of Derivative Liability Amount Offset Against Collateral DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral	1225000	USD
CY2016Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	0	USD
CY2017Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	1225000	USD
CY2017Q4	us-gaap	Derivative Liability Collateral Right To Reclaim Cash Offset DerivativeLiabilityCollateralRightToReclaimCashOffset	200000	USD
CY2016Q4	us-gaap	Derivative Liability Fair Value Gross Asset DerivativeLiabilityFairValueGrossAsset	302000	USD
CY2017Q4	us-gaap	Derivative Liability Fair Value Gross Asset DerivativeLiabilityFairValueGrossAsset	748000	USD
CY2017Q4	us-gaap	Derivative Net Liability Position Aggregate Fair Value DerivativeNetLiabilityPositionAggregateFairValue	2000000	USD
CY2015	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.88
CY2016	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.94
CY2017	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	4.22
CY2015	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.87
CY2016	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.94
CY2017	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	4.21
CY2015	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.190
CY2016	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.155
CY2017	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.186
CY2015	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2016	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2015	us-gaap	Electric Domestic Regulated Revenue ElectricDomesticRegulatedRevenue	1151038000	USD
CY2016	us-gaap	Electric Domestic Regulated Revenue ElectricDomesticRegulatedRevenue	1145993000	USD
CY2017	us-gaap	Electric Domestic Regulated Revenue ElectricDomesticRegulatedRevenue	1205976000	USD
CY2015	us-gaap	Electric Utility Revenue ElectricUtilityRevenue	1267505000	USD
CY2016	us-gaap	Electric Utility Revenue ElectricUtilityRevenue	1259353000	USD
CY2017	us-gaap	Electric Utility Revenue ElectricUtilityRevenue	1344893000	USD
CY2015	us-gaap	Electrical Generation Revenue ElectricalGenerationRevenue	30887000	USD
CY2016	us-gaap	Electrical Generation Revenue ElectricalGenerationRevenue	25205000	USD
CY2017	us-gaap	Electrical Generation Revenue ElectricalGenerationRevenue	33382000	USD
CY2016Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	45787000	USD
CY2017Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	47018000	USD
CY2017	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	0	USD
CY2016Q4	us-gaap	Energy Related Inventory Other Fossil Fuel EnergyRelatedInventoryOtherFossilFuel	53698000	USD
CY2017Q4	us-gaap	Energy Related Inventory Other Fossil Fuel EnergyRelatedInventoryOtherFossilFuel	56638000	USD
CY2015	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	12458000	USD
CY2016	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	25641000	USD
CY2017	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	24975000	USD
CY2016Q4	us-gaap	Equity Method Investments EquityMethodInvestments	11213000	USD
CY2017Q4	us-gaap	Equity Method Investments EquityMethodInvestments	11345000	USD
CY2015	us-gaap	Gain Loss On Sale Of Other Investments GainLossOnSaleOfOtherInvestments	97000	USD
CY2016	us-gaap	Gain Loss On Sale Of Other Investments GainLossOnSaleOfOtherInvestments	103000	USD
CY2017	us-gaap	Gain Loss On Sale Of Other Investments GainLossOnSaleOfOtherInvestments	131000	USD
CY2015	us-gaap	Impairment Of Long Lived Assets Held For Use ImpairmentOfLongLivedAssetsHeldForUse	0	USD
CY2016	us-gaap	Impairment Of Long Lived Assets Held For Use ImpairmentOfLongLivedAssetsHeldForUse	0	USD
CY2017	us-gaap	Impairment Of Long Lived Assets Held For Use ImpairmentOfLongLivedAssetsHeldForUse	0	USD
CY2015	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	240235000	USD
CY2016	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	234517000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	261848000	USD
CY2015	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	11128000	USD
CY2016	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	12871000	USD
CY2017	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	11374000	USD
CY2015	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	45760000	USD
CY2016	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	36429000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	48660000	USD
CY2015	us-gaap	Income Tax Expense Benefit Continuing Operations Adjustment Of Deferred Tax Asset Liability IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability	0	USD
CY2016	us-gaap	Income Tax Expense Benefit Continuing Operations Adjustment Of Deferred Tax Asset Liability IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability	0	USD
CY2017	us-gaap	Income Tax Expense Benefit Continuing Operations Adjustment Of Deferred Tax Asset Liability IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability	1690000	USD
CY2015	us-gaap	Income Tax Reconciliation Deductions IncomeTaxReconciliationDeductions	6459000	USD
CY2016	us-gaap	Income Tax Reconciliation Deductions IncomeTaxReconciliationDeductions	4997000	USD
CY2017	us-gaap	Income Tax Reconciliation Deductions IncomeTaxReconciliationDeductions	0	USD
CY2015	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	84154000	USD
CY2015	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	8857000	USD
CY2016	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	3302000	USD
CY2017	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	14742000	USD
CY2016Q4	us-gaap	Income Taxes Receivable IncomeTaxesReceivable	12781000	USD
CY2016	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	82151000	USD
CY2017	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	91378000	USD
CY2015	us-gaap	Income Tax Reconciliation Nondeductible Expense Depreciation IncomeTaxReconciliationNondeductibleExpenseDepreciation	17149000	USD
CY2016	us-gaap	Income Tax Reconciliation Nondeductible Expense Depreciation IncomeTaxReconciliationNondeductibleExpenseDepreciation	18673000	USD
CY2017	us-gaap	Income Tax Reconciliation Nondeductible Expense Depreciation IncomeTaxReconciliationNondeductibleExpenseDepreciation	18953000	USD
CY2015	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-1021000	USD
CY2016	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-3680000	USD
CY2017	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-9528000	USD
CY2015	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	7343000	USD
CY2016	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	5071000	USD
CY2017	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	8153000	USD
CY2015	us-gaap	Income Tax Reconciliation Tax Credits Investment IncomeTaxReconciliationTaxCreditsInvestment	2963000	USD
CY2016	us-gaap	Income Tax Reconciliation Tax Credits Investment IncomeTaxReconciliationTaxCreditsInvestment	2922000	USD
CY2017	us-gaap	Income Tax Reconciliation Tax Credits Investment IncomeTaxReconciliationTaxCreditsInvestment	3081000	USD
CY2015	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	3258000	USD
CY2016	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	2579000	USD
CY2017	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	2559000	USD
CY2017Q4	us-gaap	Income Taxes Receivable IncomeTaxesReceivable	8147000	USD
CY2015	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	2440000	USD
CY2016	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	13300000	USD
CY2017	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	-17208000	USD
CY2015	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	-4740000	USD
CY2016	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	2671000	USD
CY2017	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	-4005000	USD
CY2015	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	818000	USD
CY2016	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	662000	USD
CY2017	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	4361000	USD
CY2015	us-gaap	Increase Decrease In Other Current Assets IncreaseDecreaseInOtherCurrentAssets	14861000	USD
CY2016	us-gaap	Increase Decrease In Other Current Assets IncreaseDecreaseInOtherCurrentAssets	10887000	USD
CY2017	us-gaap	Increase Decrease In Other Current Assets IncreaseDecreaseInOtherCurrentAssets	-2814000	USD
CY2015	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	403000	USD
CY2016	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	-3283000	USD
CY2017	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	1017000	USD
CY2015	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-3021000	USD
CY2016	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	3897000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	8835000	USD
CY2015	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-2367000	USD
CY2016	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-1006000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-1093000	USD
CY2015	us-gaap	Increase Decrease In Regulatory Assets And Liabilities IncreaseDecreaseInRegulatoryAssetsAndLiabilities	-13699000	USD
CY2016	us-gaap	Increase Decrease In Regulatory Assets And Liabilities IncreaseDecreaseInRegulatoryAssetsAndLiabilities	5650000	USD
CY2017	us-gaap	Increase Decrease In Regulatory Assets And Liabilities IncreaseDecreaseInRegulatoryAssetsAndLiabilities	-57131000	USD
CY2015	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	72000	shares
CY2016	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	75000	shares
CY2015	us-gaap	Interest Expense Other InterestExpenseOther	8922000	USD
CY2016	us-gaap	Interest Expense Other InterestExpenseOther	10273000	USD
CY2017	us-gaap	Interest Expense Other InterestExpenseOther	11242000	USD
CY2015	us-gaap	Interest Income Other InterestIncomeOther	1774000	USD
CY2016	us-gaap	Interest Income Other InterestIncomeOther	2082000	USD
CY2017	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	63000	shares
CY2015	us-gaap	Insured Event Gain Loss InsuredEventGainLoss	1739000	USD
CY2016	us-gaap	Insured Event Gain Loss InsuredEventGainLoss	2588000	USD
CY2017	us-gaap	Insured Event Gain Loss InsuredEventGainLoss	2090000	USD
CY2015	us-gaap	Interest Costs Capitalized Adjustment InterestCostsCapitalizedAdjustment	10044000	USD
CY2016	us-gaap	Interest Costs Capitalized Adjustment InterestCostsCapitalizedAdjustment	10194000	USD
CY2017	us-gaap	Interest Costs Capitalized Adjustment InterestCostsCapitalizedAdjustment	8694000	USD
CY2015	us-gaap	Interest Expense InterestExpense	81934000	USD
CY2016	us-gaap	Interest Expense InterestExpense	82035000	USD
CY2017	us-gaap	Interest Expense InterestExpense	83746000	USD
CY2015	us-gaap	Interest Expense Debt InterestExpenseDebt	83056000	USD
CY2016	us-gaap	Interest Expense Debt InterestExpenseDebt	81956000	USD
CY2017	us-gaap	Interest Expense Debt InterestExpenseDebt	81198000	USD
CY2017	us-gaap	Interest Income Other InterestIncomeOther	2310000	USD
CY2015	us-gaap	Interest Paid Net InterestPaidNet	79442000	USD
CY2016	us-gaap	Interest Paid Net InterestPaidNet	78334000	USD
CY2017	us-gaap	Interest Paid Net InterestPaidNet	80004000	USD
CY2016Q4	us-gaap	Interest Payable Current InterestPayableCurrent	22377000	USD
CY2017Q4	us-gaap	Interest Payable Current InterestPayableCurrent	22379000	USD
CY2015	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	2890000	USD
CY2016	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	4466000	USD
CY2017	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	3872000	USD
CY2015	us-gaap	Investment Tax Credit InvestmentTaxCredit	492000	USD
CY2016	us-gaap	Investment Tax Credit InvestmentTaxCredit	305000	USD
CY2017	us-gaap	Investment Tax Credit InvestmentTaxCredit	7425000	USD
CY2016Q4	us-gaap	Investments Investments	125174000	USD
CY2017Q4	us-gaap	Investments Investments	115698000	USD
CY2015	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	4400000	USD
CY2016	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	4900000	USD
CY2017	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	5600000	USD
CY2016Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	6289897000	USD
CY2017Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	6045405000	USD
CY2016Q4	us-gaap	Liabilities Current LiabilitiesCurrent	249715000	USD
CY2017Q4	us-gaap	Liabilities Current LiabilitiesCurrent	200749000	USD
CY2016Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	2137702000	USD
CY2017Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	1842419000	USD
CY2016Q4	us-gaap	Life Insurance Corporate Or Bank Owned Amount LifeInsuranceCorporateOrBankOwnedAmount	57553000	USD
CY2017Q4	us-gaap	Life Insurance Corporate Or Bank Owned Amount LifeInsuranceCorporateOrBankOwnedAmount	59323000	USD
CY2016Q4	us-gaap	Long Term Debt LongTermDebt	1745678000	USD
CY2017Q4	us-gaap	Long Term Debt LongTermDebt	1746123000	USD
CY2016Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	1064000	USD
CY2017Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	0	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	1460345000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	0	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	75000000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	0	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	230000000	USD
CY2017Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	0	USD
CY2016Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1744614000	USD
CY2017Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1746123000	USD
CY2016Q4	us-gaap	Long Term Investments LongTermInvestments	125164000	USD
CY2017Q4	us-gaap	Long Term Investments LongTermInvestments	115698000	USD
CY2016Q4	us-gaap	Longterm Pollution Control Bond Current And Noncurrent LongtermPollutionControlBondCurrentAndNoncurrent	170460000	USD
CY2017Q4	us-gaap	Longterm Pollution Control Bond Current And Noncurrent LongtermPollutionControlBondCurrentAndNoncurrent	170460000	USD
CY2014Q4	us-gaap	Minority Interest MinorityInterest	4364000	USD
CY2015Q4	us-gaap	Minority Interest MinorityInterest	4160000	USD
CY2016Q4	us-gaap	Minority Interest MinorityInterest	3960000	USD
CY2017Q4	us-gaap	Minority Interest MinorityInterest	4729000	USD
CY2015	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-3494000	USD
CY2016	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-103584000	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-139551000	USD
CY2015	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-291706000	USD
CY2016	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-297444000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-283300000	USD
CY2015	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	353194000	USD
CY2016	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	347706000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	438020000	USD
CY2015	us-gaap	Net Income Loss NetIncomeLoss	194679000	USD
CY2016	us-gaap	Net Income Loss NetIncomeLoss	198288000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	212419000	USD
CY2015	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	-204000	USD
CY2016	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	-200000	USD
CY2017	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	769000	USD
CY2015	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	25905000	USD
CY2016	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	27664000	USD
CY2017	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	23741000	USD
CY2015	us-gaap	Operating Expenses OperatingExpenses	988192000	USD
CY2016	us-gaap	Operating Expenses OperatingExpenses	990244000	USD
CY2017	us-gaap	Operating Expenses OperatingExpenses	1045135000	USD
CY2015	us-gaap	Operating Income Loss OperatingIncomeLoss	282097000	USD
CY2016	us-gaap	Operating Income Loss OperatingIncomeLoss	271776000	USD
CY2017	us-gaap	Operating Income Loss OperatingIncomeLoss	304351000	USD
CY2016Q4	us-gaap	Other Assets Current OtherAssetsCurrent	5961000	USD
CY2017Q4	us-gaap	Other Assets Current OtherAssetsCurrent	18000	USD
CY2016Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	62058000	USD
CY2017Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	55118000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-2882000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-394000	USD
CY2016	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	29000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	5990000	USD
CY2015	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	1851000	USD
CY2016	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	253000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-1555000	USD
CY2015	us-gaap	Other General Expense OtherGeneralExpense	15129000	USD
CY2016	us-gaap	Other General Expense OtherGeneralExpense	8188000	USD
CY2017	us-gaap	Other General Expense OtherGeneralExpense	13186000	USD
CY2015	us-gaap	Other Interest And Dividend Income OtherInterestAndDividendIncome	3039000	USD
CY2016	us-gaap	Other Interest And Dividend Income OtherInterestAndDividendIncome	4241000	USD
CY2017	us-gaap	Other Interest And Dividend Income OtherInterestAndDividendIncome	6128000	USD
CY2016Q4	us-gaap	Other Inventory Supplies OtherInventorySupplies	57858000	USD
CY2017Q4	us-gaap	Other Inventory Supplies OtherInventorySupplies	55745000	USD
CY2016Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	9763000	USD
CY2017Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	10182000	USD
CY2016Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	45084000	USD
CY2017Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	44566000	USD
CY2015	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-2788000	USD
CY2016	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-5108000	USD
CY2017	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-8454000	USD
CY2015	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	21000	USD
CY2017	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	20000	USD
CY2015	us-gaap	Other Nonoperating Income OtherNonoperatingIncome	777000	USD
CY2016	us-gaap	Other Nonoperating Income OtherNonoperatingIncome	767000	USD
CY2017	us-gaap	Other Nonoperating Income OtherNonoperatingIncome	833000	USD
CY2015	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	7159000	USD
CY2016	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	9874000	USD
CY2017	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	9085000	USD
CY2016Q4	us-gaap	Other Receivables OtherReceivables	15280000	USD
CY2017Q4	us-gaap	Other Receivables OtherReceivables	30438000	USD
CY2015	us-gaap	Other Sales Revenue Net OtherSalesRevenueNet	2784000	USD
CY2016	us-gaap	Other Sales Revenue Net OtherSalesRevenueNet	2667000	USD
CY2017	us-gaap	Other Sales Revenue Net OtherSalesRevenueNet	4593000	USD
CY2015	us-gaap	Other Tax Expense Benefit OtherTaxExpenseBenefit	2337000	USD
CY2016	us-gaap	Other Tax Expense Benefit OtherTaxExpenseBenefit	-520000	USD
CY2017	us-gaap	Other Tax Expense Benefit OtherTaxExpenseBenefit	227000	USD
CY2015	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-801000	USD
CY2016	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-1144000	USD
CY2017	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-2481000	USD
CY2015	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	3277000	USD
CY2016	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	3329000	USD
CY2017	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	3212000	USD
CY2015	us-gaap	Payments Of Debt Extinguishment Costs PaymentsOfDebtExtinguishmentCosts	17872000	USD
CY2016	us-gaap	Payments Of Debt Extinguishment Costs PaymentsOfDebtExtinguishmentCosts	13895000	USD
CY2017	us-gaap	Payments Of Debt Extinguishment Costs PaymentsOfDebtExtinguishmentCosts	0	USD
CY2015	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	96810000	USD
CY2016	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	104984000	USD
CY2017	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	113127000	USD
CY2015	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	14106000	USD
CY2016	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	14917000	USD
CY2017	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	11356000	USD
CY2015	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	30000000	USD
CY2016	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	10000000	USD
CY2017	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	0	USD
CY2015	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	294021000	USD
CY2016	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	296950000	USD
CY2017	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	285488000	USD
CY2015	us-gaap	Pension And Other Postretirement Benefit Contributions PensionAndOtherPostretirementBenefitContributions	42843000	USD
CY2016	us-gaap	Pension And Other Postretirement Benefit Contributions PensionAndOtherPostretirementBenefitContributions	45301000	USD
CY2017	us-gaap	Pension And Other Postretirement Benefit Contributions PensionAndOtherPostretirementBenefitContributions	46589000	USD
CY2015	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	30207000	USD
CY2016	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	29581000	USD
CY2017	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	28911000	USD
CY2016Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	411523000	USD
CY2017Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	438869000	USD
CY2016Q4	us-gaap	Plant Held For Future Use Amount PlantHeldForFutureUseAmount	7441000	USD
CY2017Q4	us-gaap	Plant Held For Future Use Amount PlantHeldForFutureUseAmount	8075000	USD
CY2016Q4	us-gaap	Prepaid Expense Current PrepaidExpenseCurrent	18389000	USD
CY2017Q4	us-gaap	Prepaid Expense Current PrepaidExpenseCurrent	16984000	USD
CY2015	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	250000000	USD
CY2016	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	120000000	USD
CY2017	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	0	USD
CY2015	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-3171000	USD
CY2016	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-2112000	USD
CY2017	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-348000	USD
CY2015	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-11300000	USD
CY2016	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	1800000	USD
CY2017	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-21800000	USD
CY2015	us-gaap	Proceeds From Sale Of Available For Sale Securities Equity ProceedsFromSaleOfAvailableForSaleSecuritiesEquity	34243000	USD
CY2016	us-gaap	Proceeds From Sale Of Available For Sale Securities Equity ProceedsFromSaleOfAvailableForSaleSecuritiesEquity	15693000	USD
CY2017	us-gaap	Proceeds From Sale Of Available For Sale Securities Equity ProceedsFromSaleOfAvailableForSaleSecuritiesEquity	4989000	USD
CY2015	us-gaap	Profit Loss ProfitLoss	194475000	USD
CY2016	us-gaap	Profit Loss ProfitLoss	198088000	USD
CY2017	us-gaap	Profit Loss ProfitLoss	213188000	USD
CY2016Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	4171999000	USD
CY2017Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	4283875000	USD
CY2016Q4	us-gaap	Property Plant And Equipment Other PropertyPlantAndEquipmentOther	15922000	USD
CY2017Q4	us-gaap	Property Plant And Equipment Other PropertyPlantAndEquipmentOther	15488000	USD
CY2015	us-gaap	Public Utilities Allowance For Funds Used During Construction Additions PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions	21785000	USD
CY2016	us-gaap	Public Utilities Allowance For Funds Used During Construction Additions PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions	22031000	USD
CY2017	us-gaap	Public Utilities Allowance For Funds Used During Construction Additions PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions	20784000	USD
CY2015	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	21785000	USD
CY2016	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	22031000	USD
CY2017	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	20784000	USD
CY2015	us-gaap	Public Utilities Allowance For Funds Used During Construction Rate PublicUtilitiesAllowanceForFundsUsedDuringConstructionRate	0.076
CY2016	us-gaap	Public Utilities Allowance For Funds Used During Construction Rate PublicUtilitiesAllowanceForFundsUsedDuringConstructionRate	0.076
CY2017	us-gaap	Public Utilities Allowance For Funds Used During Construction Rate PublicUtilitiesAllowanceForFundsUsedDuringConstructionRate	0.076
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Accumulated Depreciation PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation	1988477000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Accumulated Depreciation PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation	2098274000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Construction Work In Progress PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress	405069000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Construction Work In Progress PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress	452424000	USD
CY2015	us-gaap	Public Utilities Property Plant And Equipment Disclosure Of Composite Depreciation Rate For Plants In Service PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService	0.0268
CY2016	us-gaap	Public Utilities Property Plant And Equipment Disclosure Of Composite Depreciation Rate For Plants In Service PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService	0.0264
CY2017	us-gaap	Public Utilities Property Plant And Equipment Disclosure Of Composite Depreciation Rate For Plants In Service PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService	0.0287
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Distribution PublicUtilitiesPropertyPlantAndEquipmentDistribution	1637131000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Distribution PublicUtilitiesPropertyPlantAndEquipmentDistribution	1710126000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Generation Or Processing PublicUtilitiesPropertyPlantAndEquipmentGenerationOrProcessing	2551823000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Generation Or Processing PublicUtilitiesPropertyPlantAndEquipmentGenerationOrProcessing	2598940000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	3743567000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	3807888000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Other Property Plant And Equipment PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment	422187000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Other Property Plant And Equipment PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment	433856000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Plant In Service PublicUtilitiesPropertyPlantAndEquipmentPlantInService	5732044000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Plant In Service PublicUtilitiesPropertyPlantAndEquipmentPlantInService	5906162000	USD
CY2016Q4	us-gaap	Public Utilities Property Plant And Equipment Transmission PublicUtilitiesPropertyPlantAndEquipmentTransmission	1120903000	USD
CY2017Q4	us-gaap	Public Utilities Property Plant And Equipment Transmission PublicUtilitiesPropertyPlantAndEquipmentTransmission	1163240000	USD
CY2016Q4	us-gaap	Real Estate Investments Unconsolidated Real Estate And Other Joint Ventures RealEstateInvestmentsUnconsolidatedRealEstateAndOtherJointVentures	7643000	USD
CY2017Q4	us-gaap	Real Estate Investments Unconsolidated Real Estate And Other Joint Ventures RealEstateInvestmentsUnconsolidatedRealEstateAndOtherJointVentures	5521000	USD
CY2015	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-2668000	USD
CY2016	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-2253000	USD
CY2017	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-1882000	USD
CY2016Q4	us-gaap	Regulatory Assets RegulatoryAssets	1471899000	USD
CY2017Q4	us-gaap	Regulatory Assets RegulatoryAssets	1132096000	USD
CY2016Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	62570000	USD
CY2017Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	48613000	USD
CY2016Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	1409329000	USD
CY2017Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	1083483000	USD
CY2016Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	446789000	USD
CY2017Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	699448000	USD
CY2016Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	9944000	USD
CY2017Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	1404000	USD
CY2016Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	436845000	USD
CY2017Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	698044000	USD
CY2015	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	121064000	USD
CY2016	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	101064000	USD
CY2017	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	1064000	USD
CY2016Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	1323198000	USD
CY2017Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	1426528000	USD
CY2015	us-gaap	Sales Revenue Net SalesRevenueNet	1270289000	USD
CY2016	us-gaap	Sales Revenue Net SalesRevenueNet	1262020000	USD
CY2017	us-gaap	Sales Revenue Net SalesRevenueNet	1349486000	USD
CY2016Q4	us-gaap	Secured Debt SecuredDebt	1575000000	USD
CY2017Q4	us-gaap	Secured Debt SecuredDebt	1575000000	USD
CY2016Q4	us-gaap	Secured Debt Current SecuredDebtCurrent	1064000	USD
CY2017Q4	us-gaap	Secured Debt Current SecuredDebtCurrent	0	USD
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	72397	shares
CY2017	us-gaap	Share Based Goods And Nonemployee Services Transaction Quantity Of Securities Issued ShareBasedGoodsAndNonemployeeServicesTransactionQuantityOfSecuritiesIssued	12050	shares
CY2016Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	21800000	USD
CY2017Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	0	USD
CY2016Q4	us-gaap	Short Term Debt Weighted Average Interest Rate ShortTermDebtWeightedAverageInterestRate	0.0113
CY2017Q4	us-gaap	Short Term Debt Weighted Average Interest Rate ShortTermDebtWeightedAverageInterestRate	0.0000
CY2016	us-gaap	Shortterm Debt Average Outstanding Amount ShorttermDebtAverageOutstandingAmount	16130000	USD
CY2017	us-gaap	Shortterm Debt Average Outstanding Amount ShorttermDebtAverageOutstandingAmount	1427000	USD
CY2017	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	0	shares
CY2015Q4	us-gaap	Stockholders Equity StockholdersEquity	2057884000	USD
CY2016Q4	us-gaap	Stockholders Equity StockholdersEquity	2153906000	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	2251385000	USD
CY2015Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2062044000	USD
CY2016Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2157866000	USD
CY2017Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2256114000	USD
CY2015	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	32808000	USD
CY2016	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	32823000	USD
CY2017	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	34089000	USD
CY2016Q4	us-gaap	Taxes Payable Current TaxesPayableCurrent	11348000	USD
CY2017Q4	us-gaap	Taxes Payable Current TaxesPayableCurrent	11075000	USD
CY2016Q4	us-gaap	Trading Securities TradingSecurities	111000	USD
CY2017Q4	us-gaap	Trading Securities TradingSecurities	17000	USD
CY2016Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	23244	shares
CY2017Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	27657	shares
CY2016Q4	us-gaap	Treasury Stock Value TreasuryStockValue	243000	USD
CY2017Q4	us-gaap	Treasury Stock Value TreasuryStockValue	1386000	USD
CY2016Q4	us-gaap	Unamortized Debt Issuance Expense UnamortizedDebtIssuanceExpense	20731000	USD
CY2017Q4	us-gaap	Unamortized Debt Issuance Expense UnamortizedDebtIssuanceExpense	19222000	USD
CY2016Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	80738000	USD
CY2017Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	75120000	USD
CY2015Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	USD
CY2016Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	USD
CY2016	us-gaap	Utilities Operating Expense Maintenance And Operations UtilitiesOperatingExpenseMaintenanceAndOperations	351893000	USD
CY2015	us-gaap	Utilities Operating Expense UtilitiesOperatingExpense	973063000	USD
CY2016	us-gaap	Utilities Operating Expense UtilitiesOperatingExpense	982056000	USD
CY2017	us-gaap	Utilities Operating Expense UtilitiesOperatingExpense	1031949000	USD
CY2015	us-gaap	Utilities Operating Expense Depreciation And Amortization UtilitiesOperatingExpenseDepreciationAndAmortization	138110000	USD
CY2016	us-gaap	Utilities Operating Expense Depreciation And Amortization UtilitiesOperatingExpenseDepreciationAndAmortization	143661000	USD
CY2017	us-gaap	Utilities Operating Expense Depreciation And Amortization UtilitiesOperatingExpenseDepreciationAndAmortization	162091000	USD
CY2015	us-gaap	Utilities Operating Expense Fuel Used UtilitiesOperatingExpenseFuelUsed	186231000	USD
CY2016	us-gaap	Utilities Operating Expense Fuel Used UtilitiesOperatingExpenseFuelUsed	179491000	USD
CY2017	us-gaap	Utilities Operating Expense Fuel Used UtilitiesOperatingExpenseFuelUsed	145829000	USD
CY2015	us-gaap	Utilities Operating Expense Maintenance And Operations UtilitiesOperatingExpenseMaintenanceAndOperations	342146000	USD
CY2017	us-gaap	Utilities Operating Expense Maintenance And Operations UtilitiesOperatingExpenseMaintenanceAndOperations	349725000	USD
CY2015	us-gaap	Utilities Operating Expense Purchased Power UtilitiesOperatingExpensePurchasedPower	226470000	USD
CY2016	us-gaap	Utilities Operating Expense Purchased Power UtilitiesOperatingExpensePurchasedPower	245764000	USD
CY2017	us-gaap	Utilities Operating Expense Purchased Power UtilitiesOperatingExpensePurchasedPower	248950000	USD
CY2015	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	50292000	shares
CY2016	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	50373000	shares
CY2017	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	50424000	shares
CY2015	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	50220000	shares
CY2016	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	50298000	shares
CY2017	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	50361000	shares
CY2017	us-gaap	Derivatives Methods Of Accounting Nonhedging Derivatives DerivativesMethodsOfAccountingNonhedgingDerivatives	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Idaho Power is exposed to market risk relating to electricity, natural gas, and other fuel commodity prices, all of which are heavily influenced by supply and demand. Market risk may be influenced by market participants’ nonperformance of their contractual obligations and commitments, which affects the supply of or demand for the commodity. Idaho Power uses derivative instruments, such as physical and financial forward contracts, for both electricity and fuel to manage the risks relating to these commodity price exposures. The primary objectives of Idaho Power’s energy purchase and sale activity are to meet the demand of retail electric customers, maintain appropriate physical reserves to ensure reliability, and make economic use of temporary surpluses that may develop.</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">All of Idaho Power's derivative instruments have been entered into for the purpose of economically hedging forecasted purchases and sales, though none of these instruments have been designated as cash flow hedges. Idaho Power offsets fair value amounts recognized on its balance sheet and applies collateral related to derivative instruments executed with the same counterparty under the same master netting agreement. Idaho Power does not offset a counterparty's current derivative contracts with the counterparty's long-term derivative contracts, although Idaho Power's master netting arrangements would allow current and long-term positions to be offset in the event of default. Also, in the event of default, Idaho Power's master netting arrangements would allow for the offsetting of all transactions executed under the master netting arrangement. These types of transactions may include non-derivative instruments, derivatives qualifying for scope exceptions, receivables and payables arising from settled positions, and other forms of non-cash collateral (such as letters of credit).</font></div></div>
CY2017	us-gaap	Derivatives Reporting Of Derivative Activity DerivativesReportingOfDerivativeActivity	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Settlement gains and losses on electricity swap contracts are recorded on the income statement in off-system sales or purchased power depending on the forecasted position being economically hedged by the derivative contract. Settlement gains and losses on contracts for natural gas are reflected in fuel expense. Settlement gains and losses on diesel derivatives are recorded in other operations and maintenance expense.</font></div></div>
CY2017	us-gaap	Guarantees Indemnifications And Warranties Policies GuaranteesIndemnificationsAndWarrantiesPolicies	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">IDACORP and Idaho Power enter into financial agreements and power purchase and sale agreements that include indemnification provisions relating to various forms of claims or liabilities that may arise from the transactions contemplated by these agreements. Generally, a maximum obligation is not explicitly stated in the indemnification provisions and, therefore, the overall maximum amount of the obligation under such indemnification provisions cannot be reasonably estimated. IDACORP and Idaho Power periodically evaluate the likelihood of incurring costs under such indemnities based on their historical experience and the evaluation of the specific indemnities. As of </font><font style="font-family:inherit;font-size:10pt;">December 31, 2017</font><font style="font-family:inherit;font-size:10pt;">, management believes the likelihood is remote that IDACORP or Idaho Power would be required to perform under such indemnification provisions or otherwise incur any significant losses with respect to such indemnification obligations. Neither IDACORP nor Idaho Power has recorded any liability on their respective consolidated balance sheets with respect to these indemnification obligations.</font></div></div>
CY2017	us-gaap	Nature Of Operations NatureOfOperations	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Nature of Business</font></div><div style="line-height:120%;font-size:12pt;"><font style="font-family:inherit;font-size:12pt;"> </font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">IDACORP is a holding company formed in 1998 whose principal operating subsidiary is Idaho Power. Idaho Power is an electric utility engaged in the generation, transmission, distribution, sales, and purchase of electric energy and capacity with a service area covering approximately 24,000 square miles in southern Idaho and eastern Oregon. Idaho Power is regulated primarily by the state utility regulatory commissions of Idaho and Oregon and the Federal Energy Regulatory Commission (FERC). Idaho Power is the parent of Idaho Energy Resources Co. (IERCo), a joint venturer in Bridger Coal Company (BCC), which mines and supplies coal to the Jim Bridger generating plant owned in part by Idaho Power.</font></div><div style="line-height:120%;font-size:12pt;"><font style="font-family:inherit;font-size:12pt;"> </font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">IDACORP’s other significant wholly-owned subsidiaries include IDACORP Financial Services, Inc. (IFS), an investor in affordable housing and other real estate investments, and Ida-West Energy Company (Ida-West), an operator of small hydroelectric generation projects that satisfy the requirements of the Public Utility Regulatory Policies Act of 1978 (PURPA).</font></div></div>
CY2017	us-gaap	Prior Period Reclassification Adjustment Description PriorPeriodReclassificationAdjustmentDescription	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Reclassifications</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">In these consolidated financial statements, certain amounts in prior periods’ consolidated financial statements have been reclassified to conform with current period presentation. On both IDACORP's and Idaho Power's 2016 consolidated balance sheets, the $9.5 million of American Falls and Milner water rights which had previously been reported separately was reclassified to "Other" within Other Assets and Deferred Debits, respectively. Also, on Idaho Power's 2016 consolidated balance sheet, $19.7 million was reclassified from "Other" in other assets to the newly created "Long-term receivables" within Deferred Debits. </font></div></div>
CY2017	us-gaap	Use Of Estimates UseOfEstimates	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Management Estimates</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"> </font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Management makes estimates and assumptions when preparing financial statements in conformity with generally accepted accounting principles. These estimates and assumptions include those related to rate regulation, retirement benefits, contingencies, asset impairment, income taxes, unbilled revenues, and bad debt. These estimates and assumptions affect the reported amounts of 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. These estimates involve judgments with respect to, among other things, future economic factors that are difficult to predict and are beyond management’s control. Accordingly, actual results could differ from those estimates.</font></div></div>

Files In Submission

Name	View Source	Status
0001057877-18-000027-index-headers.html	Edgar Link	pending
0001057877-18-000027-index.html	Edgar Link	pending
0001057877-18-000027.txt	Edgar Link	pending
0001057877-18-000027-xbrl.zip	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
ida-20171231.xml	Edgar Link	completed
ida-20171231.xsd	Edgar Link	pending
ida-20171231_cal.xml	Edgar Link	unprocessable
ida-20171231_def.xml	Edgar Link	unprocessable
ida-20171231_lab.xml	Edgar Link	unprocessable
ida-20171231_pre.xml	Edgar Link	unprocessable
ida123116_charta02.jpg	Edgar Link	pending
ida12311710k.htm	Edgar Link	pending
ida123117ex121.htm	Edgar Link	pending
ida123117ex122.htm	Edgar Link	pending
ida123117ex211.htm	Edgar Link	pending
ida123117ex231-consent.htm	Edgar Link	pending
ida123117ex232-consent.htm	Edgar Link	pending
ida123117ex311.htm	Edgar Link	pending
ida123117ex312.htm	Edgar Link	pending
ida123117ex313.htm	Edgar Link	pending
ida123117ex314.htm	Edgar Link	pending
ida123117ex321.htm	Edgar Link	pending
ida123117ex322.htm	Edgar Link	pending
ida123117ex323.htm	Edgar Link	pending
ida123117ex324.htm	Edgar Link	pending
ida123117ex951-minesafety.htm	Edgar Link	pending
ida123117ex_1012.htm	Edgar Link	pending
ida123117ex_1013.htm	Edgar Link	pending
ida123117ex_1022.htm	Edgar Link	pending
ida123117ex_1028.htm	Edgar Link	pending
ida123117ex_1037.htm	Edgar Link	pending
idcrp012cposa10.jpg	Edgar Link	pending
ipc012uposa03.jpg	Edgar Link	pending
R1.htm	Edgar Link	pending
R10.htm	Edgar Link	pending
R100.htm	Edgar Link	pending
R101.htm	Edgar Link	pending
R102.htm	Edgar Link	pending
R103.htm	Edgar Link	pending
R104.htm	Edgar Link	pending
R105.htm	Edgar Link	pending
R106.htm	Edgar Link	pending
R107.htm	Edgar Link	pending
R108.htm	Edgar Link	pending
R109.htm	Edgar Link	pending
R11.htm	Edgar Link	pending
R110.htm	Edgar Link	pending
R12.htm	Edgar Link	pending
R13.htm	Edgar Link	pending
R14.htm	Edgar Link	pending
R15.htm	Edgar Link	pending
R16.htm	Edgar Link	pending
R17.htm	Edgar Link	pending
R18.htm	Edgar Link	pending
R19.htm	Edgar Link	pending
R2.htm	Edgar Link	pending
R20.htm	Edgar Link	pending
R21.htm	Edgar Link	pending
R22.htm	Edgar Link	pending
R23.htm	Edgar Link	pending
R24.htm	Edgar Link	pending
R25.htm	Edgar Link	pending
R26.htm	Edgar Link	pending
R27.htm	Edgar Link	pending
R28.htm	Edgar Link	pending
R29.htm	Edgar Link	pending
R3.htm	Edgar Link	pending
R30.htm	Edgar Link	pending
R31.htm	Edgar Link	pending
R32.htm	Edgar Link	pending
R33.htm	Edgar Link	pending
R34.htm	Edgar Link	pending
R35.htm	Edgar Link	pending
R36.htm	Edgar Link	pending
R37.htm	Edgar Link	pending
R38.htm	Edgar Link	pending
R39.htm	Edgar Link	pending
R4.htm	Edgar Link	pending
R40.htm	Edgar Link	pending
R41.htm	Edgar Link	pending
R42.htm	Edgar Link	pending
R43.htm	Edgar Link	pending
R44.htm	Edgar Link	pending
R45.htm	Edgar Link	pending
R46.htm	Edgar Link	pending
R47.htm	Edgar Link	pending
R48.htm	Edgar Link	pending
R49.htm	Edgar Link	pending
R5.htm	Edgar Link	pending
R50.htm	Edgar Link	pending
R51.htm	Edgar Link	pending
R52.htm	Edgar Link	pending
R53.htm	Edgar Link	pending
R54.htm	Edgar Link	pending
R55.htm	Edgar Link	pending
R56.htm	Edgar Link	pending
R57.htm	Edgar Link	pending
R58.htm	Edgar Link	pending
R59.htm	Edgar Link	pending
R6.htm	Edgar Link	pending
R60.htm	Edgar Link	pending
R61.htm	Edgar Link	pending
R62.htm	Edgar Link	pending
R63.htm	Edgar Link	pending
R64.htm	Edgar Link	pending
R65.htm	Edgar Link	pending
R66.htm	Edgar Link	pending
R67.htm	Edgar Link	pending
R68.htm	Edgar Link	pending
R69.htm	Edgar Link	pending
R7.htm	Edgar Link	pending
R70.htm	Edgar Link	pending
R71.htm	Edgar Link	pending
R72.htm	Edgar Link	pending
R73.htm	Edgar Link	pending
R74.htm	Edgar Link	pending
R75.htm	Edgar Link	pending
R76.htm	Edgar Link	pending
R77.htm	Edgar Link	pending
R78.htm	Edgar Link	pending
R79.htm	Edgar Link	pending
R8.htm	Edgar Link	pending
R80.htm	Edgar Link	pending
R81.htm	Edgar Link	pending
R82.htm	Edgar Link	pending
R83.htm	Edgar Link	pending
R84.htm	Edgar Link	pending
R85.htm	Edgar Link	pending
R86.htm	Edgar Link	pending
R87.htm	Edgar Link	pending
R88.htm	Edgar Link	pending
R89.htm	Edgar Link	pending
R9.htm	Edgar Link	pending
R90.htm	Edgar Link	pending
R91.htm	Edgar Link	pending
R92.htm	Edgar Link	pending
R93.htm	Edgar Link	pending
R94.htm	Edgar Link	pending
R95.htm	Edgar Link	pending
R96.htm	Edgar Link	pending
R97.htm	Edgar Link	pending
R98.htm	Edgar Link	pending
R99.htm	Edgar Link	pending
report.css	Edgar Link	pending
serviceterritorymap2015a02.jpg	Edgar Link	pending
Show.js	Edgar Link	pending

Create your account

Find Stocks Worth Researching

Deeply Understand Businesses

Value Businesses Intelligently

$IDA
IDACORP INC Stock $ida

2017 Form 10-K Financial Statement

#000105787718000027 Filed on February 22, 2018

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$IDA IDACORP INC Stock $ida

2017 Form 10-K Financial Statement

#000105787718000027 Filed on February 22, 2018

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$IDA
IDACORP INC Stock $ida