Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 182,891	$ 119,162
Marketable securities		27,988
Restricted cash	749	749
Trade receivables, (including related parties of $6,187 and $6,172) net of allowance for doubtful accounts of $6,188 and $3,790	168,165	142,004
Assets held for sale	2,907	2,141
Prepaid expenses and other current assets (including related parties of $274 and $274)	24,803	18,021
Total current assets	379,515	310,065
Property and equipment, net of accumulated depreciation of $190,160 and $191,183	64,600	72,004
Intangible assets subject to amortization, net of accumulated amortization of $109,313 and $103,752 (including related parties of $4,949 and $5,869)	65,880	49,412
Intangible assets not subject to amortization	209,153	216,653
Goodwill	68,728	58,043
Operating leases right of use asset	32,053	33,525
Other assets	8,474	7,643
Total assets	828,403	747,345
Current liabilities
Current maturities of long-term debt	4,694	3,000
Accounts payable and accrued expenses (including related parties of $2,131 and $2,087)	179,912	126,849
Operating lease liabilities	7,353	7,290
Total current liabilities	191,959	137,139
Long-term debt, less current maturities, net of unamortized debt issuance costs of $1,986 and $1,796	208,014	210,454
Long-term operating lease liabilities	29,851	31,775
Other long-term liabilities	80,893	3,732
Deferred income taxes	64,416	54,980
Total liabilities	575,133	438,080
Commitments and contingencies (note 6)
Redeemable noncontrolling interest		33,285
Stockholders' equity
Additional paid-in capital	780,426	828,813
Accumulated deficit	(526,362)	(551,786)
Accumulated other comprehensive income (loss)	(803)	(1,056)
Total stockholders' equity	253,270	275,980
Total liabilities and stockholders' equity	828,403	747,345
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