CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Treasury	Additional paid-in capital	Retained earnings	Noncontrolling interest non- redeemable	Non controlling interest redeemable
Beginning balance at Dec. 31, 2018	$ 1,424,474	$ 358	$ (49,373)	$ 937,965	$ 427,975	$ 107,549	$ 14,596
Beginning balance (in shares) at Dec. 31, 2018		35,835,348	5,029,429
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	102,581				95,726	6,855	11,271
Net income	113,852
Acquired noncontrolling interest	10,478					10,478
Purchase of additional controlling interest	(20,565)			(2,183)		(18,382)
Sale of noncontrolling interest	1,613			819		794
Noncontrolling interest distributions	(13,366)					(13,366)	(10,716)
Nonvested stock compensation	9,646			9,646
Issuance of vested stock	2	$ 2
Issuance of vested stock (in shares)		210,986
Treasury shares redeemed to pay income tax	$ (9,679)		$ (10,687)	1,008
Treasury shares redeemed to pay income tax (in shares)	107,461		107,461
Exercise of stock options	$ 1	$ 1
Exercise of stock options (in shares)		63,051
Issuance of common stock under Employee Stock Purchase Plan	$ 2,066			2,066
Issuance of common stock under Employee Stock Purchase Plan (in shares)	19,895	19,895
Ending balance at Dec. 31, 2019	$ 1,507,251	$ 361	$ (60,060)	949,321	523,701	93,928	15,151
Ending balance (in shares) at Dec. 31, 2019		36,129,280	5,136,890
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	123,746				111,596	12,150	14,187
Net income	137,933
Acquired noncontrolling interest	5,854					5,854	3,508
Purchase of additional controlling interest	(23,913)			(1,709)		(22,204)	382
Sale of noncontrolling interest	5,290			(860)		6,150
Noncontrolling interest distributions	(11,294)					(11,294)	(13,543)
Nonvested stock compensation	14,347			14,347
Issuance of vested stock	3	$ 3
Issuance of vested stock (in shares)		195,618
Treasury shares redeemed to pay income tax	$ (9,202)		$ (9,202)	0
Treasury shares redeemed to pay income tax (in shares)	78,767		71,439
Exercise of stock options	$ (905)		$ 251	(1,156)
Exercise of stock options (in shares)		16,286	7,328
Issuance of common stock under Employee Stock Purchase Plan	$ 2,177			2,177
Issuance of common stock under Employee Stock Purchase Plan (in shares)	14,313	14,313
Ending balance at Dec. 31, 2020	$ 1,613,354	$ 364	$ (69,011)	962,120	635,297	84,584	18,921
Ending balance (in shares) at Dec. 31, 2020		36,355,497	5,215,657
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	131,673				115,728	15,945	11,943
Net income	143,616
Acquired noncontrolling interest	0					0	113
Purchase of additional controlling interest	(1,740)			(951)		(789)	(373)
Sale of noncontrolling interest	1,788			(83)		1,871
Noncontrolling interest distributions	(15,754)					(15,754)	(13,103)
Nonvested stock compensation	15,868			15,868
Issuance of vested stock	1	$ 1
Issuance of vested stock (in shares)		180,235
Treasury shares redeemed to pay income tax	$ (11,827)		$ (12,043)	216
Treasury shares redeemed to pay income tax (in shares)	63,028		64,584
Repurchase of common stock	$ (83,736)		$ (83,736)
Repurchase of common stock (in shares)	634,869		634,869
Issuance of common stock under Employee Stock Purchase Plan	$ 2,472			2,472
Issuance of common stock under Employee Stock Purchase Plan (in shares)	13,792	13,792
Ending balance at Dec. 31, 2021	$ 1,652,099	$ 365	$ (164,790)	$ 979,642	$ 751,025	$ 85,857	$ 17,501
Ending balance (in shares) at Dec. 31, 2021		36,549,524	5,915,110