Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Operating Revenue	[1]	$ 3,146	$ 2,739	$ 1,929
Operating Expenses:
Fuel used in electric generation	[1]	646	447	573
Purchased power	[1]	116	86	54
Gas purchased for resale	[1]	285	181	216
Other operations and maintenance		417	357	388
Other operations and maintenance – affiliated suppliers		189	213	244
Impairment of assets and other charges		320	111	695
Depreciation and amortization		486	474	450
Other taxes	[1]	255	239	250
Total operating expenses		2,714	2,108	2,870
Operating income (loss)		432	631	(941)
Other expense, net		(2)	(23)	(33)
Interest charges, net of allowance for funds used during construction	[1]	192	229	260
Income (loss) before income tax expense (benefit)		238	379	(1,234)
Income tax expense (benefit)		9	71	(12)
Net Income (Loss)		229	308	(1,222)
Other Comprehensive Income:
Deferred cost of employee benefit plans, net of tax		1	1	1
Total Comprehensive Income (Loss)		230	309	(1,221)
Comprehensive Income Attributable to Noncontrolling Interest		21	12	18
Comprehensive Income (Loss) Available (Attributable) to Common Shareholder		$ 209	$ 297	$ (1,239)

[1] See Note 16 for amounts attributable to affiliates.