CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Millions	Total	Common stock	Additional Paid In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2019		100
Beginning Balance at Dec. 31, 2019	$ 6,996	$ 0	$ 4,940	$ 2,083	$ (27)
Increase (Decrease) in Stockholder's Equity
Net income	237			237
Total other comprehensive income	1				1
Dividends declared to parent	(567)			(567)
Contribution of capital by parent	754		754
Adoption of ASC Topic 326	(1)			(1)
Balance (in shares) at Jun. 30, 2020		100
Ending Balance at Jun. 30, 2020	7,420	$ 0	5,694	1,752	(26)
Balance (in shares) at Mar. 31, 2020		100
Beginning Balance at Mar. 31, 2020	7,072	$ 0	4,989	2,109	(26)
Increase (Decrease) in Stockholder's Equity
Net income	108			108
Total other comprehensive income	0
Dividends declared to parent	(465)			(465)
Contribution of capital by parent	705		705
Balance (in shares) at Jun. 30, 2020		100
Ending Balance at Jun. 30, 2020	$ 7,420	$ 0	5,694	1,752	(26)
Balance (in shares) at Dec. 31, 2020	100	100
Beginning Balance at Dec. 31, 2020	$ 7,592	$ 0	5,770	1,846	(24)
Increase (Decrease) in Stockholder's Equity
Net income	301			301
Total other comprehensive income	1				1
Dividends declared to parent	(235)			(235)
Contribution of capital by parent	$ 440		440
Balance (in shares) at Jun. 30, 2021	100	100
Ending Balance at Jun. 30, 2021	$ 8,099	$ 0	6,210	1,912	(23)
Balance (in shares) at Mar. 31, 2021		100
Beginning Balance at Mar. 31, 2021	7,945	$ 0	6,070	1,898	(23)
Increase (Decrease) in Stockholder's Equity
Net income	134			134
Total other comprehensive income	0
Dividends declared to parent	(120)			(120)
Contribution of capital by parent	$ 140		140
Balance (in shares) at Jun. 30, 2021	100	100
Ending Balance at Jun. 30, 2021	$ 8,099	$ 0	$ 6,210	$ 1,912	$ (23)