Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 108,892	$ 39,560
Marketable securities	132,435
Restricted cash	769	222,294
Trade receivables, (including related parties of $5,356 and $4,653) net of allowance for doubtful accounts of $3,167 and $2,566	76,378	84,348
Assets held for sale	1,179
Prepaid expenses and other current assets (including related parties of $274 and $274)	11,990	6,260
Total current assets	331,643	352,462
Property and equipment, net of accumulated depreciation of $184,093 and $179,869	58,562	60,337
Intangible assets subject to amortization, net of accumulated amortization of $90,562 and $87,632 (including related parties of $8,941 and $9,555)	25,828	26,758
Intangible assets not subject to amortization	254,506	251,163
Goodwill	73,566	70,557
Other assets	4,442	4,690
Total assets	748,547	765,967
Current liabilities
Current maturities of long-term debt	3,000	3,000
Accounts payable and accrued expenses (including related parties of $1,920 and $2,548)	52,787	57,563
Deferred revenue	3,386	1,959
Total current liabilities	59,173	62,522
Long-term debt, less current maturities, net of unamortized debt issuance costs of $3,513 and $3,761	291,237	292,489
Other long-term liabilities	19,553	21,447
Deferred income taxes	42,326	40,639
Total liabilities	412,289	417,097
Commitments and contingencies (note 5)
Stockholders' equity
Additional paid-in capital	874,508	888,650
Accumulated deficit	(536,697)	(539,730)
Accumulated other comprehensive income (loss)	(1,562)	(60)
Total stockholders' equity	336,258	348,870
Total liabilities and stockholders' equity	748,547	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