Condensed Consolidated Statements of Stockholders' Equity - 3 months ended Mar. 31, 2018 - USD ($) $ in Thousands	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)	Non-controlling interest	Common Class A	Common Class B	Total
Balances, January 1, 2018 at Dec. 31, 2017	$ 451,199	$ 8,400	$ 459	$ (410,934)	$ 2		$ 49,126
Beginning balance, Shares at Dec. 31, 2017					17,696,991	1
Net income		4,983		4,184			9,167
Distributions to non-controlling unitholders				(4,212)			(4,212)
Equity-based compensation expense and related dividend equivalents, value	1,268	(48)					1,220
Equity-based compensation expense and related dividend equivalents, shares					46,520
Dividends to Class A common stockholders		(3,547)			$ (3,547)		(3,547)
Change in accumulated other comprehensive income			(43)	(39)			(82)
Payroll taxes related to net settled restricted stock units	(564)						(564)
Payroll taxes related to net settled restricted stock units (in shares)					(10,209)
Ending balance, Value at Mar. 31, 2018	$ 451,903	$ 9,788	$ 416	$ (411,001)	$ 2		$ 51,108
Ending balance, Shares at Mar. 31, 2018					17,733,302	1