Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Trade receivables, allowance for doubtful accounts	$ 3,926	$ 5,099
Prepaid expenses and other current assets	5,939	6,867
Intangible assets subject to amortization	24,598	26,615
Current maturities of long-term debt		1,000
Accounts payable and accrued expenses	39,750	38,550
Long-term debt, less current maturities, bond discount	4,134	4,881
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	53,514,769	52,978,304
Common stock, shares outstanding	53,514,769	52,978,304
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	5,608	5,315
Prepaid expenses and other current assets	274	274
Intangible assets subject to amortization	23,513	25,880
Current maturities of long-term debt	0	1,000
Accounts payable and accrued expenses	$ 5,691	$ 4,683