CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock.	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2020	$ 7	$ 1,047,052	$ 2,342,329	$ 3,389,388
Balance (in shares) at Dec. 31, 2020	70,906
Changes in stockholders' equity
Net income			830,407	830,407
Stock based compensation		25,787		25,787
Stock based compensation (in shares)	933
Issuance of common stock in settlement of directors' fees		151		151
Issuance of common stock in settlement of directors' fees (in shares)	3
Common stock dividends			(40,638)	(40,638)
Repurchase of common stock	$ (1)	(700,792)		(700,793)
Repurchase of common stock (in shares)	(11,422)
Balance at Sep. 30, 2021	$ 6	372,198	3,132,098	3,504,302
Balance (in shares) at Sep. 30, 2021	60,420
Balance at Jun. 30, 2021	$ 6	618,337	2,895,486	3,513,829
Balance (in shares) at Jun. 30, 2021	64,484
Changes in stockholders' equity
Net income			249,310	249,310
Stock based compensation		11,165		11,165
Stock based compensation (in shares)	130
Issuance of common stock in settlement of directors' fees		50		50
Issuance of common stock in settlement of directors' fees (in shares)	1
Common stock dividends			(12,698)	(12,698)
Repurchase of common stock		(257,354)		(257,354)
Repurchase of common stock (in shares)	(4,195)
Balance at Sep. 30, 2021	$ 6	372,198	3,132,098	3,504,302
Balance (in shares) at Sep. 30, 2021	60,420
Balance at Dec. 31, 2021	$ 6	125,396	3,292,923	3,418,325
Balance (in shares) at Dec. 31, 2021	56,867
Changes in stockholders' equity
Net income			437,890	437,890
Stock based compensation		24,686		24,686
Stock based compensation (in shares)	837
Issuance of common stock in settlement of directors' fees		154		154
Issuance of common stock in settlement of directors' fees (in shares)	3
Common stock dividends			(44,206)	(44,206)
Repurchase of common stock	$ (1)	(150,236)	(204,522)	(354,759)
Repurchase of common stock (in shares)	(6,696)
Balance at Sep. 30, 2022	$ 5		3,482,085	3,482,090
Balance (in shares) at Sep. 30, 2022	51,011
Balance at Jun. 30, 2022	$ 5		3,461,380	3,461,385
Balance (in shares) at Jun. 30, 2022	52,939
Changes in stockholders' equity
Net income			135,134	135,134
Stock based compensation		6,863		6,863
Stock based compensation (in shares)	20
Issuance of common stock in settlement of directors' fees		52		52
Issuance of common stock in settlement of directors' fees (in shares)	1
Common stock dividends			(21,642)	(21,642)
Repurchase of common stock		$ (6,915)	(92,787)	(99,702)
Repurchase of common stock (in shares)	(1,949)
Balance at Sep. 30, 2022	$ 5		$ 3,482,085	$ 3,482,090
Balance (in shares) at Sep. 30, 2022	51,011