Schedule I - Condensed Financial Information Of Registrant Schedule I - Condensed Financial Information Of Registrant (Derivative Instruments and Hedging Activities) (Details) MWh in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) MWh	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Number of Interest Rate Swaps	3
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	$ 10,393,000	$ (27,779,000)	$ (19,750,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(29,407,000)	(43,420,000)	(19,750,000)	$ 0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	10,393,000	(27,779,000)	(19,750,000)
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent	3,620,000	4,109,000	0
Collateral in a broker margin account which offsets our loss positions on the interest rate hedges.	0
Collateral in a broker margin account which offsets our loss positions on the interest rate hedges.	0
Interest Rate Contract [Member]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	(29,407,000)	(43,420,000)	(19,750,000)
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ (5,375)
Maximum Length of Time Hedged in Cash Flow Hedge	33 months
Not Designated as Hedging Instrument [Member] | FTR [Member]
Purchase of Units Derivative Instruments Financial Transmission Rights | MWh	6,091
Sale of Units Derivative Instruments Financial Transmission Rights | MWh	0
Derivative, Nonmonetary Notional Amount, Purchase (Sales), Net | MWh	6,091
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Purchase of Derivative Instruments Interest Rate Swap	$ 400,000,000
Sale of Derivative Instruments Interest Rate Swap	0
Derivative, Notional Amount, Purchase (Sales), Net	400,000,000
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Other Current Assets [Member]
Derivative Liability, Fair Value, Gross Liability	$ 49,382,000	63,215,000
Parent Company [Member]
Number of Interest Rate Swaps	3
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	$ 10,393,000	(27,779,000)	(19,750,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(29,407,000)	(43,420,000)	(19,750,000)	$ 0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	10,378,000	(27,779,000)	(19,750,000)
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent	3,636,000	4,109,000	0
Collateral in a broker margin account which offsets our loss positions on the interest rate hedges.	0
Collateral in a broker margin account which offsets our loss positions on the interest rate hedges.	0
Parent Company [Member] | Interest Rate Contract [Member]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	(29,406,000)	(43,420,000)	$ (19,750,000)
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ (5,375)
Maximum Length of Time Hedged in Cash Flow Hedge	33 months
Parent Company [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Purchase of Derivative Instruments Interest Rate Swap	$ 400,000,000
Sale of Derivative Instruments Interest Rate Swap	0
Derivative, Notional Amount, Purchase (Sales), Net	400,000,000
Parent Company [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Other Current Assets [Member]
Derivative Liability, Fair Value, Gross Liability	$ 49,382,000,000	$ 63,215,000,000