CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Preferred Stock [Member] Convertible Preferred Stock [Member]	Common Stock [Member] Common Stock Class A	Common Stock [Member] Common Stock Class B	Common Stock [Member] Common Stock Class C	Common Stock [Member] Common Stock Class D	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Total
BALANCE at Dec. 31, 2019	$ 0	$ 2	$ 3	$ 3	$ 39	$ 979,834	$ (796,806)	$ 183,075
Consolidated net loss	0	0	0	0	0	0	(8,113)	(8,113)
Stock-based compensation expense	0	0	0	0	0	2,294	0	2,294
Repurchase of shares of common stock	0	0	0	0	(3)	(3,609)	0	(3,612)
Issuance of shares of Class A common stock	0	2	0	0	0	14,671	0	14,673
Exercise of options for common stock	0	0	0	0	2	1,974	0	1,976
Adjustment of redeemable noncontrolling interests to estimated redemption value	0	0	0	0	0	(3,395)	0	(3,395)
BALANCE at Dec. 31, 2020	0	4	3	3	38	991,769	(804,919)	186,898
Consolidated net loss	0	0	0	0	0	0	38,352	38,352
Stock-based compensation expense	0	0	0	0	0	565	0	565
Repurchase of shares of common stock	0	0	0	0	(1)	(969)	0	(970)
Issuance of shares of Class A common stock	0	4	0	0	0	33,273	0	33,277
Exercise of options for common stock	0	0	0	0	0	397	0	397
Conversion of common stock	0	1	0	(1)	0	0	0	0
Adjustment of redeemable noncontrolling interests to estimated redemption value	0	0	0	0	0	(4,399)	0	(4,399)
BALANCE at Dec. 31, 2021	$ 0	$ 9	$ 3	$ 2	$ 37	$ 1,020,636	$ (766,567)	$ 254,120