CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Millions	Total	Common Stock	Additional Paid In Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Balance (in shares) at Dec. 31, 2019		1,000,000
Beginning balance at Dec. 31, 2019	$ 6,082	$ 0	$ 4,068	$ 2,036	$ (22)
Increase (Decrease) in Stockholders' Equity
Net income	107			107
Other comprehensive income	0
Dividends declared on common stock	(100)			(100)
Contribution of capital by parent	80		80
Balance (in shares) at Mar. 31, 2020		1,000,000
Ending balance at Mar. 31, 2020	$ 6,169	$ 0	4,148	2,043	(22)
Balance (in shares) at Dec. 31, 2020	1,000,000	1,000,000
Beginning balance at Dec. 31, 2020	$ 6,769	$ 0	4,585	2,206	(22)
Increase (Decrease) in Stockholders' Equity
Net income	128			128
Other comprehensive income	1				1
Dividends declared on common stock	(108)			(108)
Contribution of capital by parent	$ 400		400
Balance (in shares) at Mar. 31, 2021	1,000,000	1,000,000
Ending balance at Mar. 31, 2021	$ 7,190	$ 0	$ 4,985	$ 2,226	$ (21)