Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Trade receivables, allowance for doubtful accounts	$ 3,986	$ 3,926
Prepaid expenses and other current assets	6,365	5,939
Intangible assets subject to amortization	23,676	24,598
Accounts payable and accrued expenses	28,149	39,750
Long-term debt, less current maturities, bond discount	3,989	4,134
Class A Common Stock [Member]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	260,000,000	260,000,000
Common stock, shares issued	54,267,366	53,514,769
Common stock, shares outstanding	54,267,366	53,514,769
Class B Common Stock [Member]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	22,188,161	22,188,161
Common stock, shares outstanding	22,188,161	22,188,161
Class U Common Stock [Member]
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
Related Parties [Member]
Trade receivables, related parties	6,021	5,608
Prepaid expenses and other current assets	274	274
Intangible assets subject to amortization	22,619	23,513
Accounts payable and accrued expenses	$ 3,714	$ 5,691