Earnings Per Share (EPS) - Computation of Basic and Diluted EPS Attributable to Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Basic EPS
Net income	$ 46	$ 58	$ 109	$ 112
Weighted average shares of common stock outstanding (in shares)	69,703,792	70,448,809	69,806,319	70,250,273
Basic earnings per share (in dollars per share)	$ 0.65	$ 0.82	$ 1.56	$ 1.59
Diluted EPS
Net income	$ 46	$ 58	$ 109	$ 112
Weighted average shares of common stock outstanding (in shares)	69,703,792	70,448,809	69,806,319	70,250,273
Dilutive effect of stock options and restricted stock units (in shares)	1,000,000	3,000,000	1,000,000	2,000,000
Weighted average shares of common stock outstanding (in shares)	71,074,751	72,561,891	71,151,219	72,404,539
Diluted earnings per share (in dollars per share)	$ 0.64	$ 0.80	$ 1.53	$ 1.55
Common stock equivalents excluded from income per diluted share because of their anti-dilutive effect ( in shares )	0	0	1,000,000	1,000,000