Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Class A [Member] Common Stock [Member]	Common Class A [Member] Additional Paid-in Capital [Member]	Common Class A [Member] Treasury Stock [Member]	Common Class A [Member] Retained Earnings [Member]	Common Class A [Member] AOCI Attributable to Parent [Member]	Common Class A [Member] Parent [Member]	Common Class A [Member]	Common Class B [Member] Common Stock [Member]	Common Class B [Member] Additional Paid-in Capital [Member]	Common Class B [Member] Treasury Stock [Member]	Common Class B [Member] Retained Earnings [Member]	Common Class B [Member] AOCI Attributable to Parent [Member]	Common Class B [Member] Parent [Member]	Common Class B [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Parent [Member]	Noncontrolling Interest [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							0
Stock options exercised and stock awards															3	5,416	0	0	0	5,419		5,419
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan															0	11,520	0	0	0	11,520		11,520
Vesting of restricted share awards (in shares)	0							345
Vesting of restricted share awards															3	(6,780)	0	0	0	(6,777)		(6,777)
Issuance of common stock under employee stock purchase plan (in shares)	86							0
Issuance of common stock under employee stock purchase plan															1	1,988	0	0	0	1,989		1,989
Common stock repurchases (in shares)	(3)							(155)
Common stock repurchases															0	0	(6,483)	0	0	(6,483)		(6,483)
Dividend common stock	$ 0	$ 0	$ 0	$ (7,684)		$ (7,684)	$ (7,684)	$ 0	$ 0	$ 0	$ (2,380)		$ (2,380)	$ (2,380)
Net income															0	0	0	45,333	0	45,333		45,333
Other comprehensive income															0	0	0	0	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 adjustment																						567
Net income																						103,377
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
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							0
Stock options exercised and stock awards															2	3,926	0	0	0	3,928		3,928
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan															0	3,683	0	0	0	3,683		3,683
Vesting of restricted share awards															0	(614)	0	0	0	(614)		(614)
Common stock repurchases (in shares)	0							(99)
Common stock repurchases															0	0	(4,223)	0	0	(4,223)		(4,223)
Dividend common stock	$ 0	$ 0	$ 0	(7,735)		(7,735)	(7,735)	$ 0	$ 0	$ 0	(2,425)		(2,425)	(2,425)
Foreign currency translation adjustment																						312
Net income															0	0	0	58,044	0	58,044		58,044
Other comprehensive income															0	0	0	0	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
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)		(8,189)	(8,189)				(2,505)		(2,505)	(2,505)
Foreign currency translation adjustment																			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 adjustment																						(122)
Net income																						203,126
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
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)		$ (8,128)	$ (8,128)				$ (2,521)		$ (2,521)	$ (2,521)
Foreign currency translation adjustment																			(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