Earnings Per Share (EPS) - Computation of Basic and Diluted EPS Attributable to Common Stock (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Net income	$ 101	$ 91
Weighted average shares of common stock outstanding (in shares)	66	68
Basic earnings per share (in dollars per share)	$ 1.53	$ 1.32
Dilutive effect of stock options and restricted stock units (in shares)	1	1
Weighted average shares of common stock outstanding - diluted (in shares)	67	69
Diluted earnings per share (in dollars per share)	$ 1.51	$ 1.31
Common stock equivalents excluded from income per diluted share because of their anti-dilutive effect (in shares)	1	1