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, 2016		Sep. 30, 2016		Jun. 30, 2016	[1]	Mar. 31, 2016	[1]	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015	[1]	Mar. 31, 2015	[1]	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Numerator:
Net income	$ 1		$ 55		$ 34		$ 29		$ 3		$ 74		$ 58		$ 63		$ 120	$ 198	$ 226
Denominator:
Weighted average shares used to compute Basic EPS																	145,443	143,836	142,721
Weighted average effect of dilutive securities:
Stock options																	1,129	1,839	2,734
RSUs and other dilutive securities																	321	292	345
Weighted average shares used to compute Diluted EPS																	146,893	145,967	145,800
Basic EPS	$ 0.01	[2]	$ 0.38	[2]	$ 0.23	[2]	$ 0.20	[2]	$ 0.02	[2]	$ 0.51	[2]	$ 0.40	[2]	$ 0.44	[2]	$ 0.83	$ 1.38	$ 1.58
Diluted EPS	$ 0.01	[2]	$ 0.37	[2]	$ 0.23	[2]	$ 0.20	[2]	$ 0.02	[2]	$ 0.51	[2]	$ 0.40	[2]	$ 0.43	[2]	$ 0.82	$ 1.36	$ 1.55

[1] In the third quarter of 2016, the Company early adopted ASU 2016-09, Compensation – Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. Refer to “Note 2 – Significant Accounting Policies” for the impact of the adoption of this guidance on the first and second quarters of 2016.

[2] 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.