Condensed Consolidated Statement of Stockholder's Equity (USD $)	Total USD ($)	Additional paid-in capital USD ($)	Retained earnings USD ($)	Accumulated other comprehensive income USD ($)	Noncontrolling interest USD ($)	Common Class A USD ($)	Common Class B
Beginning balance, Value at Dec. 31, 2013	$ 15,539,000	$ 239,086,000	$ 1,506,000	$ 1,371,000	$ (226,425,000)	$ 1,000
Beginning balance, Shares at Dec. 31, 2013						11,607,971	1
Net income	22,307,000		6,788,000		15,519,000
Distributions paid to non-controlling unitholders	(11,885,000)				(11,885,000)
Share-based compensation	332,000	332,000
Dividends paid to Class A common stockholders	(1,449,000)		(1,449,000)
Change in accumulated other comprehensive income	9,000			9,000
Excess tax benefit realized on delivery of vested restricted stock units	125,000	125,000
Cancellation of vested restricted stock units to satisfy statutory tax withholding requirements	(818,000)	(818,000)				(30,519,000)
Ending balance, Value at Jun. 30, 2014	$ 24,160,000	$ 238,725,000	$ 6,845,000	$ 1,380,000	$ (222,791,000)	$ 1,000
Ending balance, Shares at Jun. 30, 2014						11,577,452	1