CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Class A Common Stock	Class A-1 Common Stock	Class A-2 Common Stock	Class B Common Stock	Total Stockholders’ Equity	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Total
Beginning balance at Dec. 31, 2016	$ 38	$ 161		$ 385	$ 112,716	$ 113,175	$ (1,043)		$ 221,992	$ 334,708
Beginning balance (in shares) at Dec. 31, 2016	3,802,972	16,100,000		38,462,541
Equity-based compensation					221	221			422	643
Issuance of shares for acquisition	$ 3				2,498	2,495			3,002	5,500
Issuance of shares for acquisition (in shares)	274,998
Net income (loss)					(4,172)		(4,172)		(8,108)	(12,280)
Ending balance at Mar. 31, 2017	$ 41	$ 161		$ 385	111,263	115,891	(5,215)		217,308	328,571
Ending balance (in shares) at Mar. 31, 2017	4,077,970	16,100,000		38,462,541
Beginning balance at Dec. 31, 2016	$ 38	$ 161		$ 385	112,716	113,175	(1,043)		221,992	334,708
Beginning balance (in shares) at Dec. 31, 2016	3,802,972	16,100,000		38,462,541
Conversion of Class A-2 to Class A (in shares)			6,731,845	40,331,989
Ending balance at Dec. 31, 2017	$ 592		$ 67	$ 404	656,647	673,141	(17,859)	$ 302	406,722	1,063,369
Ending balance (in shares) at Dec. 31, 2017	59,182,176
Noncontrolling interest in subsidiary									(161)	(161)
Equity-based compensation					1,542	1,542			939	2,481
Issuance of restricted shares	$ 3				1,424	1,421			(1,424)
Issuance of restricted shares (in shares)	331,389
Conversion of Class A-2 to Class A	$ 67		$ (67)
Conversion of Class A-2 to Class A (in shares)	6,731,839		(6,731,839)
Stock options exercised					81	81			49	130
Stock options exercised (in shares)	19,398
Issuance of shares for initial public offering					2	2			(2)
Issuance of shares for initial public offering (in shares)	27,235
Repurchase of common stock					(222)	(222)			(42)	(264)
Repurchase of common stock ( in shares)	(15,234)		(6)
Restricted shares forfeited					(70)	(70)			70
Restricted shares forfeited (in shares)	(18,640)
Foreign currency translation adjustment					(259)			(259)	(158)	(417)
Net income (loss)					10,099		10,099		6,033	16,132
Ending balance at Mar. 31, 2018	$ 662			$ 404	$ 669,244	$ 675,895	$ (7,760)	$ 43	$ 412,026	$ 1,081,270
Ending balance (in shares) at Mar. 31, 2018	66,258,163			40,331,989