Consolidated Statements of Changes in Common Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Retained Earnings	AOCI	Noncontrolling Interest
Beginning balance at Dec. 31, 2019	$ 3,892	$ 3,695	$ 20	$ (3)	$ 180
Beginning balance (in shares) at Dec. 31, 2019		40
Total comprehensive income (loss) available (attributable) to common shareholder	160		157		3
Ending balance at Jun. 30, 2020	4,052	$ 3,695	177	(3)	183
Ending balance (in shares) at Jun. 30, 2020		40
Beginning balance at Mar. 31, 2020	3,985	$ 3,695	108	(3)	185
Beginning balance (in shares) at Mar. 31, 2020		40
Total comprehensive income (loss) available (attributable) to common shareholder	67		69		(2)
Ending balance at Jun. 30, 2020	4,052	$ 3,695	177	(3)	183
Ending balance (in shares) at Jun. 30, 2020		40
Beginning balance at Dec. 31, 2020	4,484	$ 4,017	277	(2)	192
Beginning balance (in shares) at Dec. 31, 2020		40
Total comprehensive income (loss) available (attributable) to common shareholder	(71)		(80)		9
Dividend to parent	(105)		(75)		(30)
Ending balance at Jun. 30, 2021	4,308	$ 4,017	122	(2)	171
Ending balance (in shares) at Jun. 30, 2021		40
Beginning balance at Mar. 31, 2021	4,464	$ 4,017	253	(2)	196
Beginning balance (in shares) at Mar. 31, 2021		40
Total comprehensive income (loss) available (attributable) to common shareholder	(126)		(131)		5
Dividend to parent	(30)				(30)
Ending balance at Jun. 30, 2021	$ 4,308	$ 4,017	$ 122	$ (2)	$ 171
Ending balance (in shares) at Jun. 30, 2021		40