Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 33,123	$ 46,733
Marketable securities	91,662	132,424
Restricted cash	734	732
Trade receivables (including related parties of $4,251 and $4,530), net of allowance for doubtful accounts of $2,890 and $3,395	71,406	79,308
Assets held for sale	950	1,179
Prepaid expenses and other current assets (including related parties of $274 and $274)	11,557	10,672
Total current assets	209,432	271,048
Property and equipment, net of accumulated depreciation of $188,579 and $187,375	79,642	64,939
Intangible assets subject to amortization, net of accumulated amortization of $99,819 and $93,793 (including related parties of $7,098 and $8,327)	16,772	22,598
Intangible assets not subject to amortization	252,544	254,598
Goodwill	46,511	74,292
Operating leases right of use asset	43,837
Other assets	7,462	2,934
Total assets	656,200	690,409
Current liabilities
Current maturities of long-term debt	3,000	3,000
Accounts payable and accrued expenses (including related parties of $2,147 and $1,948)	53,931	51,034
Operating lease liabilities	9,056
Total current liabilities	65,987	54,034
Long-term debt, less current maturities, net of unamortized debt issuance costs of $2,226 and $2,709	213,024	240,541
Long-term operating lease liabilities	41,387
Other long-term liabilities	3,371	16,418
Deferred income taxes	44,259	46,684
Total liabilities	368,028	357,677
Commitments and contingencies (note 12)
Stockholders' equity
Additional paid-in capital	836,170	862,299
Accumulated deficit	(547,876)	(528,164)
Accumulated other comprehensive income (loss)	(131)	(1,412)
Total stockholders' equity	288,172	332,732
Total liabilities and stockholders' equity	656,200	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