Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member] Common Class A [Member]	Common Stock [Member] Common Class B [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member] Common Class A [Member]	Retained Earnings [Member] Common Class B [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Parent [Member] Common Class A [Member]	Parent [Member] Common Class B [Member]	Parent [Member]	Noncontrolling Interest [Member]	Common Class A [Member]	Common Class B [Member]	Total
Balance (in shares) at Dec. 31, 2020	42,504	12,470
Balance at Dec. 31, 2020			$ 551	$ 437,646	$ (2,879)			$ 831,850	$ 869			$ 1,268,037				$ 1,268,037
Stock options exercised and stock awards (in shares)	298
Stock options exercised and stock awards			3	5,416								5,419				5,419
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan				11,520								11,520				11,520
Vesting of restricted share awards (in shares)		345
Vesting of restricted share awards			3	(6,780)								(6,777)				(6,777)
Issuance of common stock under employee stock purchase plan (in shares)	86
Issuance of common stock under employee stock purchase plan			1	1,988								1,989				1,989
Common stock repurchases (in shares)	(3)	(155)
Common stock repurchases					(6,483)							(6,483)				(6,483)
Dividend common stock						$ (7,684)	$ (2,380)			$ (7,684)	$ (2,380)			$ (7,684)	$ (2,380)
Net income								45,333				45,333				45,333
Other comprehensive income									255			255				255
Balance (in shares) at Mar. 31, 2021	42,885	12,660
Balance at Mar. 31, 2021			558	449,790	(9,362)			867,119	1,124			1,309,229				1,309,229
Balance (in shares) at Dec. 31, 2020	42,504	12,470
Balance at Dec. 31, 2020			551	437,646	(2,879)			831,850	869			1,268,037				1,268,037
Foreign currency translation																96
Net income																172,776
Balance (in shares) at Sep. 30, 2021	43,018	12,475
Balance at Sep. 30, 2021			561	462,406	(24,814)			973,665	965			1,412,783				1,412,783
Balance (in shares) at Mar. 31, 2021	42,885	12,660
Balance at Mar. 31, 2021			558	449,790	(9,362)			867,119	1,124			1,309,229				1,309,229
Stock options exercised and stock awards (in shares)	219
Stock options exercised and stock awards			2	3,926								3,928				3,928
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan				3,683								3,683				3,683
Vesting of restricted share awards				(614)								(614)				(614)
Common stock repurchases (in shares)		(99)
Common stock repurchases					(4,223)							(4,223)				(4,223)
Dividend common stock						(7,735)	(2,425)			(7,735)	(2,425)			(7,735)	(2,425)
Net income								58,044				58,044				58,044
Other comprehensive income									312			312				312
Balance (in shares) at Jun. 30, 2021	43,104	12,561
Balance at Jun. 30, 2021			560	456,785	(13,585)			915,003	1,436			1,360,199				1,360,199
Stock options exercised and stock awards (in shares)	22
Stock options exercised and stock awards				371								371				371
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan				3,144								3,144				3,144
Vesting of restricted share awards (in shares)		2
Vesting of restricted share awards				(53)								(53)				(53)
Issuance of common stock under employee stock purchase plan (in shares)	63
Issuance of common stock under employee stock purchase plan			1	2,159								2,160				2,160
Common stock repurchases (in shares)	(171)	(88)
Common stock repurchases					(11,229)							(11,229)				(11,229)
Dividend common stock						(8,199)	(2,538)			(8,199)	(2,538)			(8,199)	(2,538)
Foreign currency translation																(471)
Net income								69,399				69,399				69,399
Other comprehensive income									(471)			(471)				(471)
Balance (in shares) at Sep. 30, 2021	43,018	12,475
Balance at Sep. 30, 2021			561	462,406	(24,814)			973,665	965			1,412,783				1,412,783
Balance (in shares) at Dec. 31, 2021	43,108	12,399
Balance at Dec. 31, 2021			563	470,750	(36,933)			1,031,582	787			1,466,749				1,466,749
Stock options exercised and stock awards (in shares)	112
Stock options exercised and stock awards			1	2,384								2,385				2,385
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan				13,793								13,793				13,793
Vesting of restricted share awards (in shares)		302
Vesting of restricted share awards			3	(7,215)								(7,212)				(7,212)
Issuance of common stock under employee stock purchase plan (in shares)	66
Issuance of common stock under employee stock purchase plan			1	2,434								2,435				2,435
Common stock repurchases (in shares)	(192)	(104)
Common stock repurchases					(15,315)							(15,315)				(15,315)
Dividend common stock						(8,189)	(2,505)			(8,189)	(2,505)			(8,189)	(2,505)
Foreign currency translation									445			445				445
Net income								92,453				92,453				92,453
Balance (in shares) at Mar. 31, 2022	43,094	12,597
Balance at Mar. 31, 2022			568	482,146	(52,248)			1,113,341	1,232			1,545,039				1,545,039
Balance (in shares) at Dec. 31, 2021	43,108	12,399
Balance at Dec. 31, 2021			563	470,750	(36,933)			1,031,582	787			1,466,749				1,466,749
Foreign currency translation																(5,823)
Net income																293,789
Balance (in shares) at Sep. 30, 2022	42,374	12,092
Balance at Sep. 30, 2022			571	494,703	(123,781)			1,291,602	(5,637)			1,657,458	$ 18,561			1,676,019
Balance (in shares) at Mar. 31, 2022	43,094	12,597
Balance at Mar. 31, 2022			568	482,146	(52,248)			1,113,341	1,232			1,545,039				1,545,039
Stock options exercised and stock awards (in shares)	162
Stock options exercised and stock awards			2	3,244								3,246				3,246
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan				4,203								4,203				4,203
Vesting of restricted share awards				(1,423)								(1,423)				(1,423)
Common stock repurchases (in shares)	(448)	(331)
Common stock repurchases					(38,438)							(38,438)				(38,438)
Dividend common stock						(8,128)	(2,521)			(8,128)	(2,521)			(8,128)	(2,521)
Foreign currency translation									(567)			(567)				(567)
Net income								110,227				110,227	446			110,673
Reclassification of foreign currency translation related to equity method									(601)			(601)				(601)
Noncontrolling interest equity													17,828			17,828
Balance (in shares) at Jun. 30, 2022	42,808	12,266
Balance at Jun. 30, 2022			570	488,170	(90,686)			1,212,919	64			1,611,037	18,274			1,629,311
Stock options exercised and stock awards (in shares)	11
Stock options exercised and stock awards				227								227				227
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan				3,554								3,554				3,554
Vesting of restricted share awards (in shares)		2
Vesting of restricted share awards				(31)								(31)				(31)
Issuance of common stock under employee stock purchase plan (in shares)	68
Issuance of common stock under employee stock purchase plan			1	2,783								2,784				2,784
Common stock repurchases (in shares)	(513)	(176)
Common stock repurchases					(33,095)							(33,095)				(33,095)
Dividend common stock						$ (8,995)	$ (2,698)			$ (8,995)	$ (2,698)			$ (8,995)	$ (2,698)
Foreign currency translation									(5,701)			(5,701)				(5,701)
Net income								90,376				90,376	287			90,663
Balance (in shares) at Sep. 30, 2022	42,374	12,092
Balance at Sep. 30, 2022			$ 571	$ 494,703	$ (123,781)			$ 1,291,602	$ (5,637)			$ 1,657,458	$ 18,561			$ 1,676,019