Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Common stock [Member]	Additional paid-in capital [Member]	Retained earnings [Member]	Treasury stock [Member]	Accumulated other comprehensive income (loss), net [Member]	Total
Balance in the beginning at Dec. 31, 2015	$ 513	$ 997,926	$ 38,670	$ (419,660)	$ 95	$ 617,544
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			13,069			13,069
Stock-based compensation		2,692				2,692
Issuance under purchase and equity compensation plans, including (gain) loss on reissuance of treasury stock	1	(2,953)		2,669		(283)
Repurchase of shares				(87,310)		(87,310)
Cash dividends declared			(4,392)			(4,392)
Other comprehensive income (loss)					8,452	8,452
Balance in the ending at Sep. 30, 2016	514	997,665	47,347	(504,301)	8,547	549,772
Balance in the beginning at Dec. 31, 2016	514	984,087	55,454	(502,104)	(1,762)	536,189
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			24,698			24,698
Stock-based compensation		2,771				2,771
Issuance under purchase and equity compensation plans, including (gain) loss on reissuance of treasury stock	1	(12,898)		5,850		(7,047)
Cash dividends declared			(6,794)			(6,794)
Warrant exercise		(1,933)		1,933
Other comprehensive income (loss)					427	427
Balance in the ending at Sep. 30, 2017	$ 515	$ 972,027	$ 73,358	$ (494,321)	$ (1,335)	$ 550,244