Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ 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, Common [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, 2021	43,108,000	12,399,000
Balance at Dec. 31, 2021	$ 1,466,749		$ 563	$ 470,750	$ (36,933)			$ 1,031,582	$ 787			$ 1,466,749
Stock options exercised and stock awards (in shares)	112,000
Stock options exercised and stock awards	$ 2,385		1	2,384								2,385
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan				13,793								13,793
Vesting of restricted share awards (in shares)		302,000
Vesting of restricted share awards	$ (7,212)		3	(7,215)								(7,212)
Issuance of common stock under employee stock purchase plan (in shares)	66,000
Issuance of common stock under employee stock purchase plan	$ 2,435		1	2,434								2,435
Common stock repurchases (in shares)	(192,000)	(104,000)
Common stock repurchases	$ (15,315)				(15,315)							(15,315)
Cash dividends declared						$ (8,189)	$ (2,505)			$ (8,189)	$ (2,505)
Foreign currency translation adjustment									445			445
Net income								92,453				92,453
Foreign currency translation									445			445
Balance (in shares) at Mar. 31, 2022	43,094,000	12,597,000
Balance at Mar. 31, 2022	$ 1,545,039		568	482,146	(52,248)			1,113,341	1,232			1,545,039
Balance (in shares) at Dec. 31, 2021	43,108,000	12,399,000
Balance at Dec. 31, 2021	$ 1,466,749		563	470,750	(36,933)			1,031,582	787			1,466,749
Foreign currency translation adjustment																$ (122)
Net income																203,126
Foreign currency translation																(122)
Balance (in shares) at Jun. 30, 2022	42,808,000	12,266,000
Balance at Jun. 30, 2022			570	488,170	(90,686)			1,212,919	64			1,611,037	$ 18,274			1,629,311
Balance (in shares) at Mar. 31, 2022	43,094,000	12,597,000
Balance at Mar. 31, 2022	$ 1,545,039		568	482,146	(52,248)			1,113,341	1,232			1,545,039
Stock options exercised and stock awards (in shares)	162,000
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)	(448,000)	(331,000)
Common stock repurchases					(38,438)							(38,438)				(38,438)
Cash dividends declared						(8,128)	(2,521)			(8,128)	(2,521)			$ (8,128)	$ (2,521)
Foreign currency translation adjustment									(567)			(567)				(567)
Net income								110,227				110,227	446			110,673
Foreign currency translation									(567)			(567)				(567)
Balance (in shares) at Jun. 30, 2022	42,808,000	12,266,000
Balance at Jun. 30, 2022			570	488,170	(90,686)			1,212,919	64			1,611,037	18,274			1,629,311
Reclassification of foreign currency translation related to equity method									(601)			(601)				(601)
Noncontrolling interest equity													17,828			17,828
Balance (in shares) at Dec. 31, 2022	42,345,000	12,083,000
Balance at Dec. 31, 2022			572	500,642	(130,930)			1,378,337	(4,130)			1,744,491				1,763,022
Stock options exercised and stock awards (in shares)	152
Stock options exercised and stock awards			2	3,412								3,414				3,414
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan				13,080								13,080				13,080
Vesting of restricted share awards (in shares)		281,000
Vesting of restricted share awards			3	(6,964)								(6,961)				(6,961)
Issuance of common stock under employee stock purchase plan (in shares)	68,000
Issuance of common stock under employee stock purchase plan				2,828								2,828				2,828
Common stock repurchases (in shares)	(415,000)	(56,000)
Common stock repurchases					(25,280)							(25,280)				(25,280)
Cash dividends declared						(8,897)	(2,692)			(8,897)	(2,692)			(8,897)	(2,692)
Foreign currency translation adjustment									232			232				232
Net income								90,455				90,455	335			90,790
Foreign currency translation									232			232				232
Balance (in shares) at Mar. 31, 2023	42,150,000	12,308,000
Balance at Mar. 31, 2023			577	512,998	(156,210)			1,457,203	(3,898)			1,810,670	18,866			1,829,536
Balance (in shares) at Dec. 31, 2022	42,345,000	12,083,000
Balance at Dec. 31, 2022			572	500,642	(130,930)			1,378,337	(4,130)			1,744,491				1,763,022
Foreign currency translation adjustment																1,921
Net income																189,314
Foreign currency translation																1,921
Balance (in shares) at Jun. 30, 2023	41,715,000	12,179,000
Balance at Jun. 30, 2023			578	522,375	(196,515)			1,543,941	(2,209)			1,868,170	19,115			1,887,285
Balance (in shares) at Mar. 31, 2023	42,150,000	12,308,000
Balance at Mar. 31, 2023			577	512,998	(156,210)			1,457,203	(3,898)			1,810,670	18,866			1,829,536
Stock options exercised and stock awards (in shares)	158,000
Stock options exercised and stock awards			1	3,479								3,480				3,480
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan				5,952								5,952				5,952
Vesting of restricted share awards				(54)								(54)				(54)
Common stock repurchases (in shares)	(593,000)	(129,000)
Common stock repurchases					(40,305)							(40,305)				(40,305)
Cash dividends declared						$ (8,812)	$ (2,725)			$ (8,812)	$ (2,725)			$ (8,812)	$ (2,725)
Foreign currency translation adjustment									1,689			1,689				1,689
Net income								98,275				98,275	249			98,524
Foreign currency translation									1,689			1,689				1,689
Balance (in shares) at Jun. 30, 2023	41,715,000	12,179,000
Balance at Jun. 30, 2023			$ 578	$ 522,375	$ (196,515)			$ 1,543,941	$ (2,209)			$ 1,868,170	$ 19,115			$ 1,887,285