Consolidated Statements of Capitalization - Capital Stock - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Beginning balance	$ 4,216	$ 3,695	$ 3,303
Net income	446	424	370
Equity contributions from Parent	580	505	395
Dividends to Parent	(450)	(408)	(373)
Ending balance	4,792	4,216	3,695
Common Stock [Member]
Beginning balance	$ 3,890	$ 3,385	$ 2,990
Beginning balance	10	10	10
Equity contributions from Parent	$ 580	$ 505	$ 395
Ending balance	$ 4,470	$ 3,890	$ 3,385
Ending balance	10	10	10
Retained Earnings [Member]
Beginning balance	$ 327	$ 311	$ 314
Net income	446	424	370
Dividends to Parent	(450)	(408)	(373)
Ending balance	323	327	311
Accumulated Other Comprehensive Loss [Member]
Beginning balance	(1)	(1)	(1)
Ending balance	$ (1)	$ (1)	$ (1)