CONSOLIDATED STATEMENT OF STOCKHOLDERS' DEFICIT - USD ($) shares in Thousands, $ in Thousands	Total	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Class A Common Stock	Class A Common Stock Common Stock	Class B Common Stock	Class B Common Stock Common Stock
Beginning balance at Dec. 31, 2015	$ (21,597)	$ 344,518	$ (366,459)	$ 7	$ (74)		$ 401		$ 10
Beginning balance (in shares) at Dec. 31, 2015							40,064		988
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(6,858)		(6,849)		(9)
Other comprehensive (loss) income	(75)			(75)
Issuances of Class A common stock	528	523					$ 5
Issuances of Class A common stock (in shares)							508
Stock-based compensation	3,393	3,393
Contributions from noncontrolling interest holder	59				59
Ending balance at Dec. 31, 2016	(24,550)	348,434	(373,308)	(68)	(24)		$ 406		$ 10
Ending balance (in shares) at Dec. 31, 2016						40,572	40,572	988	988
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(21,799)		(21,799)		0
Other comprehensive (loss) income	252			252
Issuances of Class A common stock	1,779	1,772					$ 7
Issuances of Class A common stock (in shares)							726
Stock-based compensation	6,432	6,432
Other	24				24
Ending balance at Dec. 31, 2017	(37,862)	356,638	(395,107)	184	0		$ 413		$ 10
Ending balance (in shares) at Dec. 31, 2017						41,298	41,298	988	988
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	6,420		6,420		0
Other comprehensive (loss) income	(1,474)			(1,474)
Issuances of Class A common stock	1,017	1,012					$ 5
Issuances of Class A common stock (in shares)							496
Stock-based compensation	8,445	8,445
Issuance of Class A common stock - acquisition	7,622	7,621					$ 1
Issuance of Class A common stock - acquisition (in shares)							150
Ending balance at Dec. 31, 2018	$ (15,832)	$ 373,716	$ (388,669)	$ (1,308)	$ 0		$ 419		$ 10
Ending balance (in shares) at Dec. 31, 2018						41,944	41,944	988	988