Condensed Consolidated Statements of Stockholders' Equity (unaudited) - USD ($) $ in Thousands	Total	Additional Paid-in Capital	Treasury Stock	(Accumulated Deficit) Retained Earnings	Noncontrolling Interests	Class A Common Stock Common Stock	Class B Common Stock Common Stock
Beginning balance (in shares) at Dec. 31, 2015			(150,993)			7,759,092	6,841,667
Beginning balance at Dec. 31, 2015	$ 68,054	$ 44,591	$ (1,542)	$ (3,093)	$ 28,083	$ 8	$ 7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	13,109			4,513	8,596
Issuances of Class A common stock under equity compensation plans (in shares)						246,164
Issuance of Class A common stock under equity compensation plans	19	19
Class A common stock withheld in Treasury from restricted share vesting (in shares)			21,397			(21,397)
Class A common stock withheld in Treasury from restricted share vesting	(160)		$ (160)
Forfeiture of restricted stock held in Treasury (in shares)			43,600			(43,600)
Forfeiture of restricted stock held in Treasury		345	$ (345)
Issuances of restricted shares from treasury (in shares)			(75,749)			75,749
Issuances of restricted shares from treasury		(721)	$ 721
Issuances of Class A common stock from treasury (in shares)			(20,697)			20,697
Issuances of Class A common stock from treasury	21	(183)	$ 204
Stock compensation expense	3,792	3,792
Contributions (distributions)	(4,757)	6			(4,763)
Ending balance (in shares) at Dec. 31, 2016			(119,544)			8,036,705	6,841,667
Ending balance at Dec. 31, 2016	80,078	47,849	$ (1,122)	1,420	31,916	$ 8	$ 7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,474			10,217	5,257
Issuances of Class A common stock under equity compensation plans (in shares)						1,444,169
Issuance of Class A common stock under equity compensation plans	$ 20	19				$ 1
Class A common stock withheld in Treasury from restricted share vesting (in shares)	(11,627)		11,627			(11,627)
Class A common stock withheld in Treasury from restricted share vesting	$ (185)		$ (185)
Stock compensation expense	1,755	1,755
Contributions (distributions)	(1,732)	2			(1,734)
Issuance of Class A common stock in private offering (in shares)						3,000,000
Issuance of Class A common stock in private offering	16,487	16,484				$ 3
Exchange of Series B Membership interest and exchange and cancellation of Class B common stock (in shares)							(3,000,000)
Exchange of Series B Membership interest and exchange and cancellation of Class B common stock	(14,374)				(14,371)		$ (3)
Ending balance (in shares) at Jun. 30, 2017			(131,171)			12,469,247	3,841,667
Ending balance at Jun. 30, 2017	$ 97,523	$ 66,109	$ (1,307)	$ 11,637	$ 21,068	$ 12	$ 4