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, 2019	Mar. 31, 2018
Basic EPS
Net income	$ 63	$ 54
Weighted average shares of common stock outstanding (in shares)	69,909,984	70,047,752
Basic earnings per share (in dollars per share)	$ 0.91	$ 0.77
Diluted EPS
Net income	$ 63	$ 54
Weighted average shares of common stock outstanding (in shares)	69,909,984	70,047,752
Dilutive effect of stock options and restricted stock units (in shares)	1,000,000	2,000,000
Weighted average shares of common stock outstanding (in shares)	71,247,427	72,274,821
Diluted earnings per share (in dollars per share)	$ 0.89	$ 0.75
Common stock equivalents excluded from income per diluted share because of their anti-dilutive effect ( in shares )	1,000,000	1,000,000