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, 2020	$ 4,484	$ 4,017	$ 277	$ (2)	$ 192
Beginning balance (in shares) at Dec. 31, 2020		40
Total comprehensive income available to common shareholder	77		64		13
Capital contribution from parent	149	$ 149
Dividend to parent	(180)		(150)		(30)
Ending balance at Sep. 30, 2021	4,530	$ 4,166	191	(2)	175
Ending balance (in shares) at Sep. 30, 2021		40
Beginning balance at Jun. 30, 2021	4,308	$ 4,017	122	(2)	171
Beginning balance (in shares) at Jun. 30, 2021		40
Total comprehensive income available to common shareholder	148		144		4
Capital contribution from parent	149	$ 149
Dividend to parent	(75)		(75)
Ending balance at Sep. 30, 2021	4,530	$ 4,166	191	(2)	175
Ending balance (in shares) at Sep. 30, 2021		40
Beginning balance at Dec. 31, 2021	4,525	$ 4,016	335	(1)	175
Beginning balance (in shares) at Dec. 31, 2021		40
Total comprehensive income available to common shareholder	406		390		16
Capital contribution from parent	72	$ 72
Dividend to parent	(348)		(315)		(33)
Ending balance at Sep. 30, 2022	4,655	$ 4,088	410	(1)	158
Ending balance (in shares) at Sep. 30, 2022		40
Beginning balance at Jun. 30, 2022	4,612	$ 4,088	357	(1)	168
Beginning balance (in shares) at Jun. 30, 2022		40
Total comprehensive income available to common shareholder	173		168		5
Dividend to parent	(130)		(115)		(15)
Ending balance at Sep. 30, 2022	$ 4,655	$ 4,088	$ 410	$ (1)	$ 158
Ending balance (in shares) at Sep. 30, 2022		40