Earnings Per Share - Reconciliation of Weighted Average Number of Shares of Common Stock Outstanding In Calculating EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income (loss)	$ 15		$ 50		$ 34		$ 26		$ 7		$ 69		$ 32		$ 5		$ 126	$ 113	$ (19)
Denominator:
Weighted average shares used to compute Basic EPS																	138,975	138,116	140,445
Weighted average effect of dilutive securities:
Stock options																	155	351
RSUs/MSUs																	1,528	1,908
Weighted average shares used to compute Diluted EPS																	140,658	140,375	140,445
Basic EPS	$ 0.11	[1]	$ 0.36	[1]	$ 0.24	[1]	$ 0.19	[1]	$ 0.05	[1]	$ 0.50	[1]	$ 0.23	[1]	$ 0.04	[1]	$ 0.91	$ 0.82	$ (0.14)
Diluted EPS	$ 0.11	[1]	$ 0.36	[1]	$ 0.24	[1]	$ 0.18	[1]	$ 0.05	[1]	$ 0.49	[1]	$ 0.23	[1]	$ 0.04	[1]	$ 0.89	$ 0.81	$ (0.14)

[1] Earnings per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly earnings per share may not equal the total computed for the year.