Earnings Per Share (EPS) - Computation of Basic and Diluted EPS Attributable to Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Basic EPS
Net income	$ 54	$ 29
Weighted average shares of common stock outstanding (in shares)	70,047,752	68,509,328
Basic EPS (in dollars per share)	$ 0.77	$ 0.42
Diluted EPS
Net income	$ 54	$ 29
Weighted average shares of common stock outstanding (in shares)	70,047,752	68,509,328
Dilutive effect of stock options and restricted stock units (in shares)	2,000,000	2,000,000
Weighted average shares of common stock outstanding (in shares)	72,274,821	70,913,970
Diluted EPS (in dollars per share)	$ 0.75	$ 0.41
Common stock equivalents excluded from income per diluted share because of their anti-dilutive effect (in shares)	1,000,000	1,000,000