CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Common Stock	Treasury	Additional paid-in capital	Retained earnings	Noncontrolling interest -non- redeemable	Total equity	Non controlling interest - redeemable	Net income
Beginning balance (in shares) at Dec. 31, 2015		22,224,423	4,776,560
Beginning balance at Dec. 31, 2015		$ 222	$ (37,139)	$ 113,793	$ 277,706	$ 3,211	$ 357,793	$ 12,408
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					36,583	1,373	37,956	7,986
Net income	$ 45,942								$ 45,942
Acquired noncontrolling interest						1,783	1,783	0
Sale of noncontrolling interest				(931)		1,400	469
Noncontrolling interest distributions						(1,341)	(1,341)	(7,827)
Stock options exercised (in shares)		5,500
Stock options exercised				109			109
Nonvested stock compensation				4,872			4,872
Issuance of vested stock (in shares)		174,969
Issuance of vested stock		$ 2		(2)
Treasury shares redeemed to pay income tax (in shares)	52,119		52,119
Treasury shares redeemed to pay income tax			$ (1,996)				(1,996)
Excess tax benefits-vesting nonvested stock				995			995
Issuance of common stock under Employee Stock Purchase Plan		$ 0		912			912
Issuance of common stock under Employee Stock Purchase Plan (in shares)	24,149	24,149
Ending balance (in shares) at Dec. 31, 2016		22,429,041	4,828,679
Ending balance at Dec. 31, 2016		$ 224	$ (39,135)	119,748	314,289	6,426	401,552	12,567
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					50,112	(595)	49,517	10,869
Net income	$ 60,386								60,386
Acquired noncontrolling interest						53,657	53,657
Purchase of additional controlling interest				(368)			(368)	(1,120)
Sale of noncontrolling interest				122		282	404	412
Noncontrolling interest distributions						(2,047)	(2,047)	(9,335)
Nonvested stock compensation				5,964			5,964
Issuance of vested stock (in shares)		192,463
Issuance of vested stock		$ 2		(2)
Treasury shares redeemed to pay income tax (in shares)	61,825		61,825
Treasury shares redeemed to pay income tax			$ (3,114)				(3,114)
Issuance of common stock under Employee Stock Purchase Plan		$ 0		1,026			1,026
Issuance of common stock under Employee Stock Purchase Plan (in shares)	18,542	18,542
Ending balance (in shares) at Dec. 31, 2017		22,640,046	4,890,504
Ending balance at Dec. 31, 2017	$ 506,591	$ 226	$ (42,249)	126,490	364,401	57,723	506,591	13,393
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					63,574	5,672	69,246	9,677
Net income	$ 78,923								$ 78,923
Acquired noncontrolling interest						41,055	41,055	8,230
Purchase of additional controlling interest				7,661		(371)	7,290	(7,706)
Sale of noncontrolling interest				(2,161)		6,016	3,855	590
Noncontrolling interest distributions						(2,546)	(2,546)	(9,588)
Nonvested stock compensation				9,358			9,358
Issuance of vested stock (in shares)		212,355
Issuance of vested stock		$ 3		0			3
Treasury shares redeemed to pay income tax (in shares)	68,217		68,217
Treasury shares redeemed to pay income tax			$ (7,125)				(7,125)
Merger consideration (in shares)		12,765,288
Merger consideration		$ 127		795,278			795,405
Issuance of common stock under Employee Stock Purchase Plan				1,342			1,342
Issuance of common stock under Employee Stock Purchase Plan (in shares)	18,725	18,725
Ending balance (in shares) at Dec. 31, 2018		35,636,414	4,958,721
Ending balance at Dec. 31, 2018	$ 1,424,474	$ 356	$ (49,374)	$ 937,968	$ 427,975	$ 107,549	$ 1,424,474	$ 14,596