CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Millions	Total	Common Stock	Additional Paid In Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2019		100
Beginning balance at Dec. 31, 2019	$ 2,885	$ 0	$ 2,351	$ 535	$ (1)
Increase (Decrease) in Stockholders' Equity
Net income	242			242
Dividends declared to parent	(267)			(267)
Contributions of capital by parent	436		436
Ending balance (in shares) at Sep. 30, 2020		100
Ending balance at Sep. 30, 2020	3,296	$ 0	2,787	510	(1)
Beginning balance (in shares) at Jun. 30, 2020		100
Beginning balance at Jun. 30, 2020	3,305	$ 0	2,787	519	(1)
Increase (Decrease) in Stockholders' Equity
Net income	127			127
Dividends declared to parent	(136)			(136)
Ending balance (in shares) at Sep. 30, 2020		100
Ending balance at Sep. 30, 2020	$ 3,296	$ 0	2,787	510	(1)
Beginning balance (in shares) at Dec. 31, 2020	100	100
Beginning balance at Dec. 31, 2020	$ 3,298	$ 0	2,790	509	(1)
Increase (Decrease) in Stockholders' Equity
Net income	260			260
Dividends declared to parent	(253)			(253)
Contributions of capital by parent	$ 301		301
Ending balance (in shares) at Sep. 30, 2021	100	100
Ending balance at Sep. 30, 2021	$ 3,606	$ 0	3,091	516	(1)
Beginning balance (in shares) at Jun. 30, 2021		100
Beginning balance at Jun. 30, 2021	3,597	$ 0	3,094	504	(1)
Increase (Decrease) in Stockholders' Equity
Net income	134			134
Dividends declared to parent	(122)			(122)
Contributions of capital by parent	$ (3)		(3)
Ending balance (in shares) at Sep. 30, 2021	100	100
Ending balance at Sep. 30, 2021	$ 3,606	$ 0	$ 3,091	$ 516	$ (1)