Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 48	$ 55	$ 46	$ 63	$ 29	$ 51	$ 58	$ 54	$ 212	$ 192	$ 178
Weighted average shares of common stock outstanding									70	70	69
Basic (in dollars per share)	$ 0.69	$ 0.80	$ 0.65	$ 0.91	$ 0.41	$ 0.73	$ 0.82	$ 0.77	$ 3.04	$ 2.72	$ 2.57
Net income	$ 48	$ 55	$ 46	$ 63	$ 29	$ 51	$ 58	$ 54	$ 212	$ 192	$ 178
Dilutive effect of stock options and restricted stock units									1	2	2
Weighted average shares of common stock outstanding									71	72	71
Diluted (in dollars per share)	$ 0.68	$ 0.78	$ 0.64	$ 0.89	$ 0.40	$ 0.71	$ 0.80	$ 0.75	$ 2.99	$ 2.65	$ 2.49
Common stock equivalents excluded from income per diluted share because of their anti-dilutive effect									1	1	2