Condensed Consolidated Statement of Stockholders' Equity - 9 months ended Sep. 30, 2015 - USD ($) $ in Thousands	Additional paid-in capital Class A common stock	Additional paid-in capital	Common Stock Class A common stock	Common Stock Class B common stock	Retained earnings Class A common stock	Retained earnings	Accumulated other comprehensive (loss) income	Non-controlling interest	Class A common stock	Class B common stock	Total
Beginning balance, Value at Dec. 31, 2014		$ 241,882	$ 1			$ 12,041	$ 886	$ (215,527)			$ 39,283
Beginning balance, Shares at Dec. 31, 2014			11,768,041	1					11,768,041	1
Net income						12,474		27,907			40,381
Distributions paid to non-controlling unitholders								(38,813)			(38,813)
Equity-based compensation expense		1,098									1,098
Dividends to Class A common stockholders					$ 22,454				$ 22,454
Change in accumulated other comprehensive (loss) income							(931)	(107)			(1,038)
Issuance of Class A common stock, equity-based compensation plans	$ 1,912								$ 1,912
Issuance of Class A common stock, equity-based compensation plans, shares			571,598
Excess tax benefit realized on exercise of stock options and delivery of vested restricted stock units		2,411									2,411
Ending balance, Value at Sep. 30, 2015		$ 247,303	$ 1			$ 2,061	$ (45)	$ (226,540)			$ 22,780
Ending balance, Shares at Sep. 30, 2015			12,339,639	1					12,339,639	1