Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2013	32,240,795
Balance at Dec. 31, 2013	$ 3,223	$ 109,765	$ 131,178	$ (14,984)	$ (18,962)	$ 210,220
Net income			57,303			57,303
Other comprehensive loss					(26,019)	(26,019)
Exercise of stock options (in shares)	596,135
Exercise of stock options	$ 61	4,142				4,203
Vested restricted stock		(161)		161
Stock option expense		2,491				2,491
Restricted stock expense		395				395
Performance stock expense		2,116				2,116
Excess tax benefits		517				517
Balance (in shares) at Dec. 31, 2014	32,836,930
Balance at Dec. 31, 2014	$ 3,284	119,265	188,481	(14,823)	(44,981)	251,226
Net income			57,217			57,217
Other comprehensive loss					(10,468)	(10,468)
Exercise of stock options (in shares)	691,985
Exercise of stock options	$ 69	5,747				5,816
Vested restricted stock		(76)		76
Stock option expense		2,975				2,975
Restricted stock expense		353				353
Performance stock expense		2,271				2,271
Excess tax benefits		1,445				$ 1,445
Balance (in shares) at Dec. 31, 2015	33,528,915					33,528,915
Balance at Dec. 31, 2015	$ 3,353	131,980	245,698	(14,747)	(55,449)	$ 310,835
Net income			81,678			81,678
Other comprehensive loss					(10,071)	(10,071)
Exercise of stock options (in shares)	398,680
Exercise of stock options	$ 40	4,901				4,941
Vested restricted stock		(92)		92
Stock option expense		3,816				3,816
Restricted stock expense		489				489
Performance stock expense		3,461				3,461
Excess tax benefits		10,278				$ 10,278
Balance (in shares) at Dec. 31, 2016	33,927,595					33,927,595
Balance at Dec. 31, 2016	$ 3,393	153,681	$ 327,376	(13,503)	$ (65,520)	$ 405,427
Vested performance shares		$ (1,152)		$ 1,152