Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net income applicable to common stockholders	$ 147	$ 149	$ 116	$ 46	$ 296	$ 161
Weighted Average Shares
Weighted average common shares outstanding (in shares)	52,763,868		56,790,642		52,719,959	56,723,254
Effect of dilutive securities
Stock-based awards (in shares)	772,801		333,064		697,937	433,561
Weighted average diluted common shares (in shares)	53,536,669		57,123,706		53,417,896	57,156,815
Earnings per common share
Basic earnings per common share (in dollars per share)	$ 2.78		$ 2.04		$ 5.61	$ 2.85
Effect of dilutive securities
Stock-based awards (in dollars per share)	(0.04)		(0.01)		(0.07)	(0.02)
Diluted earnings per common share (in dollars per share)	$ 2.74		$ 2.03		$ 5.54	$ 2.83