Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 46,733	$ 39,560
Marketable securities	132,424
Restricted cash	732	222,294
Trade receivables (including related parties of $4,530 and $4,653), net of allowance for doubtful accounts of $3,395 and $2,566	79,308	84,348
Assets held for sale	1,179
Prepaid expenses and other current assets (including related parties of $274 and $274)	10,672	6,260
Total current assets	271,048	352,462
Property and equipment, net of accumulated depreciation of $187,375 and $179,869	64,939	60,337
Intangible assets subject to amortization, net of accumulated amortization of $93,793 and $87,632 (including related parties of $8,327 and $9,555)	22,598	26,758
Intangible assets not subject to amortization	254,598	251,163
Goodwill	74,292	70,729
Other assets	2,934	4,690
Total assets	690,409	766,139
Current liabilities
Current maturities of long-term debt	3,000	3,000
Accounts payable and accrued expenses (including related parties of $1,948 and $2,548)	51,034	61,847
Total current liabilities	54,034	64,847
Long-term debt, less current maturities, net of unamortized debt issuance costs of $2,709 and $3,761	240,541	292,489
Other long-term liabilities	16,418	19,889
Deferred income taxes	46,684	40,639
Total liabilities	357,677	417,864
Commitments and contingencies (note 14)
Stockholders' equity
Additional paid-in capital	862,299	888,650
Accumulated deficit	(528,164)	(540,325)
Accumulated other comprehensive income (loss)	(1,412)	(60)
Total stockholders' equity	332,732	348,275
Total liabilities and stockholders' equity	690,409	766,139
Class A common stock
Stockholders' equity
Common stock	6	7
Class B common stock
Stockholders' equity
Common stock	2	2
Class U common stock
Stockholders' equity
Common stock	$ 1	$ 1