Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive stock options whose exercise prices were higher than the common stock's average market price during the period (in shares)									1	0	0
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic									$ (4,321)	$ 0	$ 0
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights									268
Net income	$ 107,609	$ 184,665	$ 259,695	$ 98,655	$ 59,174	$ 119,098	$ 157,555	$ 30,912	$ 650,624	366,738	261,575
Net Income (Loss) Available to Common Stockholders, Basic									$ 646,303	$ 366,738	$ 261,575
Weighted average shares outstanding [Abstract]
Basic (in shares)									39,876	40,106	39,833
Effect of dilutive securities [Abstract]
Stock options and employee stock purchase plan (in shares)									604	759	1,032
Diluted (in shares)									40,480	40,865	40,865
Basic (in dollars per share)	$ 2.68	$ 4.60	$ 6.47	$ 2.45	$ 1.47	$ 2.97	$ 3.94	$ 0.77	$ 16.21	$ 9.14	$ 6.57
Diluted (in dollars per share)	$ 2.65	$ 4.54	$ 6.37	$ 2.42	$ 1.45	$ 2.92	$ 3.87	$ 0.75	$ 15.97	$ 8.97	$ 6.40
Anti-dilutive stock options whose exercise prices were higher than the common stock's average market price during the period (in shares)									1	0	0