CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total
Balance at Dec. 31, 2013	$ 609	$ 170,283	$ 316,224	$ (1,140)	$ (69,471)	$ 416,505
Balance (in shares) at Dec. 31, 2013	60,885,920				6,242,326
Increase (Decrease) in Stockholders' Equity
Net income			49,370			49,370
Other comprehensive income (loss), net of tax (Note 12)				(26,370)		(26,370)
Employee and director stock plans	$ 3	6,155				6,158
Employee and director stock plans (in shares)	237,339
Share repurchase (Note 11)					$ (39,725)	(39,725)
Share repurchase (Note 11) (in shares)					1,930,841
Treasury stock purchased					$ (465)	(465)
Treasury stock purchased (in shares)					23,205
Balance at Dec. 31, 2014	$ 612	176,438	365,594	(27,510)	$ (109,661)	405,473
Balance (in shares) at Dec. 31, 2014	61,123,259				8,196,372
Increase (Decrease) in Stockholders' Equity
Net income			43,463			43,463
Other comprehensive income (loss), net of tax (Note 12)				(14,120)		(14,120)
Cash dividends			(10,430)			(10,430)
Employee and director stock plans	$ 1	5,238				5,239
Employee and director stock plans (in shares)	177,294
Share repurchase (Note 11)					$ (34,952)	(34,952)
Share repurchase (Note 11) (in shares)					2,002,444
Treasury stock purchased					$ (682)	(682)
Treasury stock purchased (in shares)					33,796
Balance at Dec. 31, 2015	$ 613	181,676	398,627	(41,630)	$ (145,295)	393,991
Balance (in shares) at Dec. 31, 2015	61,300,553				10,232,612
Increase (Decrease) in Stockholders' Equity
Net income			13,797			13,797
Other comprehensive income (loss), net of tax (Note 12)				(11,969)		(11,969)
Cash dividends			(10,138)			(10,138)
Employee and director stock plans	$ 2	4,115				4,117
Employee and director stock plans (in shares)	230,472
Share repurchase (Note 11)					$ (8,201)	(8,201)
Share repurchase (Note 11) (in shares)					518,576
Treasury stock purchased					$ (454)	(454)
Treasury stock purchased (in shares)					29,813
Balance at Dec. 31, 2016	$ 615	$ 185,791	$ 402,286	$ (53,599)	$ (153,950)	$ 381,143
Balance (in shares) at Dec. 31, 2016	61,531,025				10,781,001