Earnings Per Share - Computation (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Basic:
Net income	$ 837	$ 504	$ 544
Weighted-average shares outstanding (in shares)	53,446,399	53,441,375	53,991,249
Basic earnings per share (in USD per share)	$ 15.66	$ 9.43	$ 10.08
Diluted:
Net income	$ 837	$ 504	$ 544
Weighted-average shares outstanding (in shares)	53,446,399	53,441,375	53,991,249
Diluted Shares (in shares)	456,031	471,870	603,168
Diluted weighted-average shares outstanding (in shares)	53,902,430	53,913,245	54,594,417
Diluted earnings per share (in USD per share)	$ 15.52	$ 9.35	$ 9.97