Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings Per Share [Abstract]
Net Income	$ 307,283	$ 179,261	$ 259,695	$ 98,655	$ 486,544	$ 358,350
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic	(1,680)		0		(2,762)	0
Net Income (Loss) Available to Common Stockholders, Basic	$ 305,603		$ 259,695		$ 483,782	$ 358,350
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive stock options excluded from diluted earnings per share computations (in shares)	33		0		1	0
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights	218				229
Weighted average shares outstanding: [Abstract]
Basic (in shares)	39,660		40,125		39,795	40,169
Effect of dilutive securities: [Abstract]
Stock options and employee stock purchase plan (in shares)	404		620		436	631
Diluted (in shares)	40,064		40,745		40,231	40,800
Earnings Per Share, Basic [Abstract]
Basic (in dollars per share)	$ 7.71		$ 6.47		$ 12.16	$ 8.92
Earnings Per Share, Basic and Diluted [Abstract]
Diluted (in dollars per share)	$ 7.63		$ 6.37		$ 12.03	$ 8.78