Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Trade receivables, allowance for doubtful accounts	$ 3,139	$ 3,199
Prepaid expenses and other current assets	4,892	4,087
Accumulated Depreciation Depletion And Amortization Property Plant And Equipment	186,943	184,084
Finite Lived Intangible Assets Accumulated Amortization	72,304	71,678
Intangible assets subject to amortization, net	19,186	19,812
Accounts payable and accrued expenses	24,313	31,246
Related Parties
Trade receivables, related parties	8,374	7,102
Prepaid expenses and other current assets	274	274
Intangible assets subject to amortization, net	17,978	18,559
Accounts payable and accrued expenses	$ 3,938	$ 3,994
Class A common stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	260,000,000	260,000,000
Common stock, shares issued	60,972,640	59,793,603
Common stock, shares outstanding	60,972,640	59,793,603
Class B common stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	18,930,035	18,969,222
Common stock, shares outstanding	18,930,035	18,969,222
Class U common stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	9,352,729	9,352,729
Common stock, shares outstanding	9,352,729	9,352,729