CONSOLIDATED STATEMENT OF STOCKHOLDERS' DEFICIT - USD ($) shares in Thousands, $ in Thousands	Total	Additional Paid-In Capital	Accumulated Deficit	Accumulated other comprehensive income	Class A Common Stock	Class A Common Stock Common Stock	Class B Common Stock	Class B Common Stock Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting principle			$ 18	$ (18)
Beginning balance at Dec. 31, 2017	$ (37,862)	$ 356,638	(395,107)	184		$ 413		$ 10
Beginning balance (in shares) at Dec. 31, 2017					41,298	41,298	988	988
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(2,206)		(2,206)
Other comprehensive income	483			483
Issuances of Class A common stock	671	666				$ 5
Issuances of Class A common stock (in shares)						467
Stock-based compensation	4,198	4,198
Ending balance at Jun. 30, 2018	$ (34,716)	$ 361,502	$ (397,295)	$ 649		$ 418		$ 10
Ending balance (in shares) at Jun. 30, 2018					41,765	41,765	988	988