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, 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
Beginning balance at Dec. 31, 2022	4,666	$ 4,088	418	(2)	162
Beginning balance (in shares) at Dec. 31, 2022		40
Total comprehensive income available to common shareholder	324		309		15
Dividend to parent	(150)		(150)
Ending balance at Sep. 30, 2023	4,840	$ 4,088	577	(2)	177
Ending balance (in shares) at Sep. 30, 2023		40
Beginning balance at Jun. 30, 2023	4,744	$ 4,088	486	(2)	172
Beginning balance (in shares) at Jun. 30, 2023		40
Total comprehensive income available to common shareholder	146		141		5
Dividend to parent	(50)		(50)
Ending balance at Sep. 30, 2023	$ 4,840	$ 4,088	$ 577	$ (2)	$ 177
Ending balance (in shares) at Sep. 30, 2023		40