Condensed Consolidated Statements of Changes in Stockholders' Equity - 6 months ended Jun. 30, 2017 - USD ($) shares in Thousands, $ in Thousands	Common Stock Common Class A	Common Stock Common Class B	Additional Paid-In Capital	Treasury Stock Common Class A	Retained Earnings	Accumulated Other Comprehensive Loss	Total
Balance at the beginning of the period at Dec. 31, 2016	$ 2	$ 2	$ 261,051	$ (35,069)	$ 43,837	$ (483)	$ 269,340
Balance at the beginning of the period (in shares) at Dec. 31, 2016	24,944	20,801
Consolidated Statements of Changes in Stockholders' Equity
Net income					7,926		7,926
Purchase of common stock				(295)			(295)
Purchase of common stock (in shares)	196
Stock-based compensation			2,122				2,122
Exercise of warrants			4				4
Exercise of warrants (in shares)	0
Other comprehensive loss						(340)	(340)
Balance at the end of the period at Jun. 30, 2017	$ 2	$ 2	$ 263,177	$ (35,364)	$ 51,763	$ (823)	$ 278,757
Balance at the end of the period (in shares) at Jun. 30, 2017	25,140	20,801