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	(3,910)		(3,910)
Other comprehensive income	568			568
Issuances of Class A common stock	310	306				$ 4
Issuances of Class A common stock (in shares)						402
Stock-based compensation	2,077	2,077
Ending balance at Mar. 31, 2018	$ (38,817)	$ 359,021	$ (398,999)	$ 734		$ 417		$ 10
Ending balance (in shares) at Mar. 31, 2018					41,700	41,700	988	988