Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Trade receivables, related parties	$ 6,534	$ 6,172
Trade receivables, allowance for doubtful accounts	4,757	3,790
Prepaid expenses and other current assets	18,418	18,021
Property and equipment, accumulated depreciation	192,182	191,183
Accumulated amortization of Intangible assets	105,578	103,752
Intangible assets subject to amortization, net	47,587	49,412
Accounts payable and accrued expenses	124,369	126,849
Unamortized debt issuance costs	1,689	1,796
Related Parties
Prepaid expenses and other current assets	274	274
Intangible assets subject to amortization, net	5,563	5,869
Accounts payable and accrued expenses	$ 2,042	$ 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	60,765,450	60,759,405
Common stock, shares outstanding	60,765,450	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	14,927,613	14,927,613
Common stock, shares outstanding	14,927,613	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