Consolidated statement of changes in stockholders' equity - 6 months ended Jun. 30, 2018 - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member] Class A Common Stock [Member]	Common Stock [Member] Class B Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning balance at Dec. 31, 2017	$ 60,591	$ 2	$ 4	$ 232,156	$ (166,499)	$ (5,072)
Beginning balance (in shares) at Dec. 31, 2017		26,725	36,508
Net income	5,433				5,433
Follow-on public offering, net of offering costs of $370	135,201	$ 1	$ (1)	135,201
Follow-on public offering, net of offering costs of $370 (shares)		5,731	(1,675)
Adjustment for acquisitions	(96)			(96)
Conversion from Class B to Class A		1,662	(1,662)
Exercise of stock options	1,669	$ 1		1,668
Exercise of stock options (in shares)		2,400
Stock-based compensation	650			650
Foreign currency translation, net of tax	(1,842)					(1,842)
Retirement related benefit plans, net of tax	106					106
Ending balance at Jun. 30, 2018	$ 201,712	$ 4	$ 3	$ 369,579	$ (161,066)	$ (6,808)
Ending balance (in shares) at Jun. 30, 2018		36,518	33,171