Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 52,631	$ 46,733
Marketable securities	113,349	132,424
Restricted cash	732	732
Trade receivables, (including related parties of $5,145 and $4,530) net of allowance for doubtful accounts of $3,032 and $3,395	69,841	79,308
Assets held for sale	1,179	1,179
Prepaid expenses and other current assets (including related parties of $274 and $274)	12,558	10,672
Total current assets	250,290	271,048
Property and equipment, net of accumulated depreciation of $187,226 and $187,375	74,502	64,939
Intangible assets subject to amortization, net of accumulated amortization of $95,646 and $93,793 (including related parties of $7,712 and $8,327)	19,442	22,598
Intangible assets not subject to amortization	254,598	254,598
Goodwill	51,857	74,292
Operating leases right of use asset	46,206
Other assets	2,684	2,934
Total assets	699,579	690,409
Current liabilities
Current maturities of long-term debt	3,000	3,000
Accounts payable and accrued expenses (including related parties of $2,415 and $1,948)	46,198	51,034
Operating lease liabilities	11,420
Total current liabilities	60,618	54,034
Long-term debt, less current maturities, net of unamortized debt issuance costs of $2,718 and $2,709	239,032	240,541
Long-term operating lease liabilities	41,091
Other long-term liabilities	7,516	16,418
Deferred income taxes	48,401	46,684
Total liabilities	396,658	357,677
Commitments and contingencies (note 6)
Stockholders' equity
Additional paid-in capital	846,345	862,299
Accumulated deficit	(543,019)	(528,164)
Accumulated other comprehensive income (loss)	(414)	(1,412)
Total stockholders' equity	302,921	332,732
Total liabilities and stockholders' equity	699,579	690,409
Class A common stock
Stockholders' equity
Common stock	6	6
Class B common stock
Stockholders' equity
Common stock	2	2
Class U common stock
Stockholders' equity
Common stock	$ 1	$ 1