Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands		Dec. 31, 2023	Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets		$ 261,185	$ 285,444
Total Financial Liabilities		77,001	8,721
Nuclear Decommissioning Trust [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets	[1]	78,243	73,945
Nuclear Decommissioning Trust - Net Asset Value [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets	[1],[2]	182,364	151,318
Unrestricted Investment And Other [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets	[3]	137	279
Derivatives - Gas And Power [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets	[4]	441	59,902
Total Financial Liabilities	[4]	77,001	8,721
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets		78,243	101,784
Total Financial Liabilities		65,285
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Nuclear Decommissioning Trust [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets	[1]	78,243	73,945
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Derivatives - Gas And Power [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets	[4]		27,839
Total Financial Liabilities	[4]	65,285
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets		578	21,052
Total Financial Liabilities		10,715	8,721
Significant Other Observable Inputs (Level 2) [Member] | Unrestricted Investment And Other [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets	[3]	137	279
Significant Other Observable Inputs (Level 2) [Member] | Derivatives - Gas And Power [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets	[4]	441	20,773
Total Financial Liabilities	[4]	10,715	8,721
Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets			11,290
Total Financial Liabilities		1,001
Significant Unobservable Inputs (Level 3) | Derivatives - Gas And Power [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Financial Assets	[4]		$ 11,290
Total Financial Liabilities	[4]	$ 1,001

[1] For additional information about our nuclear decommissioning trust, see Note 8—Investments.

[2] Nuclear decommissioning trust includes investments measured at net asset value per share (or its equivalent) as a practical expedient and these investments have not been categorized in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheet.

[3] Unrestricted investments and other includes investments that are related to equity securities.

[4] Derivatives - gas and power represent natural gas futures contracts (Level 1 and Level 2) and financial transmission rights (Level 3). Level 1 are indexed against NYMEX. Level 2 are valued by ACES using observable market inputs for similar transactions. Level 3 are valued by ACES using unobservable market inputs, including situations where there is little market activity. Sensitivity in the market price of financial transmission rights could impact the fair value. For additional information about our derivative financial instruments, see Note 1—Summary of Significant Accounting Policies.