Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 119,162	$ 33,123
Marketable securities	27,988	91,662
Restricted cash	749	734
Trade receivables (including related parties of $6,172 and $4,251), net of allowance for doubtful accounts of $3,790 and $2,890	142,004	71,406
Assets held for sale	2,141	950
Prepaid expenses and other current assets (including related parties of $274 and $274)	18,021	11,557
Total current assets	310,065	209,432
Property and equipment, net of accumulated depreciation of $191,183 and $188,579	72,004	79,642
Intangible assets subject to amortization, net of accumulated amortization of $103,752 and $99,819 (including related parties of $5,869 and $7,098)	49,412	16,772
Intangible assets not subject to amortization	216,653	252,544
Goodwill	58,043	46,511
Operating leases right of use asset	33,525	43,837
Other assets	7,643	7,462
Total assets	747,345	656,200
Current liabilities
Current maturities of long-term debt	3,000	3,000
Accounts payable and accrued expenses (including related parties of $2,087 and $2,147)	126,849	53,931
Operating lease liabilities	7,290	9,056
Total current liabilities	137,139	65,987
Long-term debt, less current maturities, net of unamortized debt issuance costs of $1,796 and $2,226	210,454	213,024
Long-term operating lease liabilities	31,775	41,387
Other long-term liabilities	3,732	3,371
Deferred income taxes	54,980	44,259
Total liabilities	438,080	368,028
Commitments and contingencies (note 12)
Redeemable noncontrolling interest	33,285
Stockholders' equity
Additional paid-in capital	828,813	836,170
Accumulated deficit	(551,786)	(547,876)
Accumulated other comprehensive income (loss)	(1,056)	(131)
Total stockholders' equity	275,980	288,172
Total liabilities and stockholders' equity	747,345	656,200
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