Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Earnings Per Share [Abstract]
Net Income	$ 232,250	$ 101,699	$ 307,283	$ 179,261	$ 333,949	$ 486,544
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic	(1,219)		(1,680)		(1,779)	2,762
Net Income (Loss) Available to Common Stockholders, Basic	$ 231,031		$ 305,603		$ 332,170	$ 483,782
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)	64		33		65	1
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights	205,000		218,000		209,000	229,000
Weighted average shares outstanding: [Abstract]
Basic (in shares)	38,837		39,660		38,857	39,795
Effect of dilutive securities: [Abstract]
Stock options and employee stock purchase plan (in shares)	278		404		298	436
Diluted (in shares)	39,115		40,064		39,155	40,231
Earnings Per Share, Basic [Abstract]
Basic (in dollars per share)	$ 5.95		$ 7.71		$ 8.55	$ 12.16
Earnings Per Share, Basic and Diluted [Abstract]
Diluted (in dollars per share)	$ 5.91		$ 7.63		$ 8.48	$ 12.03