CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' DEFICIT - 9 months ended Sep. 30, 2017 - USD ($) $ in Thousands	Total	Convertible Preferred Stock [Member]	Common Class A [Member]	Common Class B [Member]	Common Class C [Member]	Common Class D [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]
BALANCE at Dec. 31, 2016	$ (71,126)	$ 0	$ 2	$ 3	$ 3	$ 41	$ 981,688	$ (1,052,863)
Consolidated net loss	(9,397)	0	0	0	0	0	0	(9,397)
Repurchase of 2,086,828 shares of Class D common stock	(4,396)	0	0	0	0	(2)	(4,394)	0
Conversion of 51,467 shares of Class A common stock to Class D common stock	0	0	0	0	0	0	0	0
Adjustment of redeemable noncontrolling interests to estimated redemption value	2,771	0	0	0	0	0	2,771	0
Stock-based compensation expense	1,946	0	0	0	0	2	1,944	0
BALANCE at Sep. 30, 2017	$ (80,202)	$ 0	$ 2	$ 3	$ 3	$ 41	$ 982,009	$ (1,062,260)