Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Trade receivables, allowance for doubtful accounts	$ 2,775	$ 3,199
Trade receivables, related parties	10,638	7,102
Prepaid expenses and other current assets	5,079	4,087
Property and equipment, accumulated depreciation	189,444	184,084
Finite lived intangible assets, accumulated amortization	72,930	71,678
Finite lived intangible assets subject to amortization	22,161	19,812
Accounts payable and accrued expenses	28,950	31,246
Related Parties
Prepaid expenses and other current assets	274	274
Finite lived intangible assets subject to amortization	17,399	18,559
Accounts payable and accrued expenses	$ 4,423	$ 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	61,032,640	59,793,603
Common stock, shares outstanding	61,032,640	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