CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Retained Earnings	Accumulated Other Comprehensive Loss	Total
Beginning balance, shares at Dec. 31, 2013	24,016
Beginning balance, value at Dec. 31, 2013	$ 73,422	$ 22,275	$ (1,095)	$ 94,602
Common stock issued upon exercise of options and warrants, shares	1,525
Common stock issued upon exercise of options and warrants	$ 3,256			3,256
Pension benefit obligation			(3,956)	(3,956)
Stock-based compensation	$ 3,835			3,835
Net income		29,516		29,516
Ending balance, shares at Dec. 31, 2014	25,541
Ending balance, value at Dec. 31, 2014	$ 80,513	51,791	(5,051)	127,253
Common stock issued upon exercise of options and warrants, shares	1,140
Common stock issued upon exercise of options and warrants	$ 1,726			1,726
Repurchase of common stock, shares	(1,064)
Repurchase of common stock, value	$ (5,926)			(5,926)
Pension benefit obligation			(1,599)	(1,599)
Stock-based compensation	$ 5,024			5,024
Net income		34,681		34,681
Ending balance, shares at Dec. 31, 2015	25,617
Ending balance, value at Dec. 31, 2015	$ 81,337	86,472	(6,650)	161,159
Common stock issued upon exercise of options and warrants, shares	448
Common stock issued upon exercise of options and warrants	$ 706			706
Repurchase of common stock, shares	(2,478)
Repurchase of common stock, value	$ (10,468)			(10,468)
Pension benefit obligation			(32)	(32)
Stock-based compensation	$ 5,553			5,553
Net income		29,300		29,300
Ending balance, shares at Dec. 31, 2016	23,587
Ending balance, value at Dec. 31, 2016	$ 77,128	$ 115,772	$ (6,682)	$ 186,218