Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Net Income	$ 137,843	$ 232,250	$ 101,699	$ 190,055	$ 307,283	$ 179,261	$ 471,792	$ 676,600
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic	726			1,019			2,504	3,764
Net Income (Loss) Available to Common Stockholders, Basic	$ 137,117			$ 189,036			$ 469,288	$ 672,836
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)	31			33			64	33
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights	205,000			213,000			207,000	223,000
Weighted average shares outstanding: [Abstract]
Basic (in shares)	38,735			39,214			38,816	39,599
Effect of dilutive securities: [Abstract]
Stock options and employee stock purchase plan (in shares)	288			366			296	413
Diluted (in shares)	39,023			39,580			39,112	40,012
Earnings Per Share, Basic [Abstract]
Basic (in dollars per share)	$ 3.54			$ 4.82			$ 12.09	$ 16.99
Earnings Per Share, Basic and Diluted [Abstract]
Diluted (in dollars per share)	$ 3.51			$ 4.78			$ 12.00	$ 16.82