CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock.	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Common Class A [Member]	Total
Balance at Dec. 31, 2018	$ 8	$ 1,310,648	$ 343,135		$ 1,653,791
Balance (in shares) at Dec. 31, 2018	77,494
Changes in stockholders' equity
Net income			392,965		392,965
Stock based compensation		25,282			25,282
Stock based compensation (in shares)	1,062
Issuance of common stock in settlement of director fees		233			233
Issuance of common stock in settlement of director fees (in shares)	10
Common stock dividends			(9,708)		(9,708)
Repurchase of common stock		(1,056)		$ (1,056)	(1,056)
Repurchase of common stock (in shares)	(51)			(51)
Balance at Dec. 31, 2019	$ 8	1,335,107	726,392		2,061,507
Balance (in shares) at Dec. 31, 2019	78,515
Changes in stockholders' equity
Net income			1,646,884		1,646,884
Stock based compensation		49,229			49,229
Stock based compensation (in shares)	1,276
Issuance of common stock in settlement of director fees		194			194
Issuance of common stock in settlement of director fees (in shares)	5
Common stock dividends			(30,947)		(30,947)
Repurchase of common stock	$ (1)	(337,478)		$ (337,479)	(337,479)
Repurchase of common stock (in shares)	(8,890)			(8,890)
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			1,003,490		1,003,490
Stock based compensation		36,337			36,337
Stock based compensation (in shares)	1,326
Issuance of common stock in settlement of director fees		200			200
Issuance of common stock in settlement of director fees (in shares)	3
Common stock dividends			(52,896)		(52,896)
Repurchase of common stock	$ (1)	(958,193)		$ (958,194)	(958,194)
Repurchase of common stock (in shares)	(15,368)			(15,368)
Balance at Dec. 31, 2021	$ 6	$ 125,396	$ 3,292,923		$ 3,418,325
Balance (in shares) at Dec. 31, 2021	56,867