Consolidated Statements of Shareholder's Equity (Unaudited) - USD ($) $ in Millions	Total	Common stock	Additional paid- in capital	Accumulated other comprehensive loss	Accumulated deficit
Balance at beginning of period at Dec. 31, 2019	$ 1,019	$ 1	$ 4,333	$ (93)	$ (3,222)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(4)			(14)	10
Balance at end of period at Mar. 31, 2020	1,015	1	4,333	(107)	(3,212)
Balance at beginning of period at Dec. 31, 2020	1,427	1	4,633	(70)	(3,137)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	28			(1)	29
Balance at end of period at Mar. 31, 2021	$ 1,455	$ 1	$ 4,633	$ (71)	$ (3,108)