Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 53,512	$ 33,123
Marketable securities	74,684	91,662
Restricted cash	734	734
Trade receivables, (including related parties of $6,759 and $4,251) net of allowance for doubtful accounts of $3,549 and $2,890	63,879	71,406
Assets held for sale	6,878	950
Prepaid expenses and other current assets (including related parties of $274 and $274)	15,108	11,557
Total current assets	214,795	209,432
Property and equipment, net of accumulated depreciation of $190,381 and $188,579	76,315	79,642
Intangible assets subject to amortization, net of accumulated amortization of $101,268 and $99,819 (including related parties of $6,791 and $7,098)	10,192	16,772
Intangible assets not subject to amortization	216,853	252,544
Goodwill	45,711	46,511
Operating leases right of use asset	41,759	43,837
Other assets	7,506	7,462
Total assets	613,131	656,200
Current liabilities
Current maturities of long-term debt	3,000	3,000
Accounts payable and accrued expenses (including related parties of $2,236 and $2,147)	55,557	53,931
Operating lease liabilities	8,802	9,056
Total current liabilities	67,359	65,987
Long-term debt, less current maturities, net of unamortized debt issuance costs of $2,120 and $2,226	212,380	213,024
Long-term operating lease liabilities	39,476	41,387
Other long-term liabilities	3,611	3,371
Deferred income taxes	42,068	44,259
Total liabilities	364,894	368,028
Commitments and contingencies (note 6)
Stockholders' equity
Additional paid-in capital	832,216	836,170
Accumulated deficit	(583,468)	(547,876)
Accumulated other comprehensive income (loss)	(520)	(131)
Total stockholders' equity	248,237	288,172
Total liabilities and stockholders' equity	613,131	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