Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 101,789	$ 39,560
Marketable securities	132,410
Restricted cash	769	222,294
Trade receivables, (including related parties of $4,253 and $4,653) net of allowance for doubtful accounts of $3,131 and $2,566	78,092	84,348
Assets held for sale	1,179
Prepaid expenses and other current assets (including related parties of $274 and $274)	13,217	6,260
Total current assets	327,456	352,462
Property and equipment, net of accumulated depreciation of $185,229 and $179,869	63,204	60,337
Intangible assets subject to amortization, net of accumulated amortization of $92,194 and $87,632 (including related parties of $8,633 and $9,555)	24,196	26,758
Intangible assets not subject to amortization	254,506	251,163
Goodwill	74,149	70,557
Other assets	5,087	4,690
Total assets	748,598	765,967
Current liabilities
Current maturities of long-term debt	3,000	3,000
Accounts payable and accrued expenses (including related parties of $2,392 and $2,548)	52,795	57,563
Deferred revenue	4,351	1,959
Total current liabilities	60,146	62,522
Long-term debt, less current maturities, net of unamortized debt issuance costs of $3,386 and $3,761	290,614	292,489
Other long-term liabilities	19,237	21,447
Deferred income taxes	43,172	40,639
Total liabilities	413,169	417,097
Commitments and contingencies (note 5)
Stockholders' equity
Additional paid-in capital	871,321	888,650
Accumulated deficit	(534,482)	(539,730)
Accumulated other comprehensive income (loss)	(1,419)	(60)
Total stockholders' equity	335,429	348,870
Total liabilities and stockholders' equity	748,598	765,967
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