Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Trade receivables, related parties	$ 6,327	$ 6,172
Trade receivables, allowance for doubtful accounts	5,377	3,790
Prepaid expenses and other current assets	23,345	18,021
Property and equipment, accumulated depreciation	190,121	191,183
Accumulated amortization of Intangible assets	107,404	103,752
Intangible assets subject to amortization, net	45,760	49,412
Accounts payable and accrued expenses	141,767	126,849
Unamortized debt issuance costs	2,138	1,796
Related Parties
Prepaid expenses and other current assets	274	274
Intangible assets subject to amortization, net	5,255	5,869
Accounts payable and accrued expenses	$ 2,122	$ 2,087
Class A common stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	260,000,000	260,000,000
Common stock, shares issued	61,189,644	60,759,405
Common stock, shares outstanding	61,189,644	60,759,405
Class B common stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	14,807,613	14,927,613
Common stock, shares outstanding	14,807,613	14,927,613
Class U common stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	9,352,729	9,352,729
Common stock, shares outstanding	9,352,729	9,352,729