Consolidated Statements of Changes In Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Loss on Pension Benefit Obligation	Currency Translation Adjustments	Foreign Currency Hedge Adjustment	Commodity Hedge Adjustment	Interest Rate Hedge Adjustment	Accumulated Earnings
Beginning Balance at Dec. 31, 2013	$ 232,094	$ 232,067	$ (9,582)	$ (1,058)	$ (4,064)			$ (81)	$ 14,812
Beginning Balance (in shares) at Dec. 31, 2013		34,929,000
Exercise of Common Stock options for cash	$ 7,176	$ 9,595	(2,419)
Exercise of Common Stock options for cash (in shares)	731,142	731,000
Tax benefit from Exercises of Common Stock options	$ 1,831		1,831
Common Stock issued to Board of Directors and employees	2,706	$ 2,706
Common Stock issued to Board of Directors and employees (in shares)		105,000
Stock option compensation	1,946		1,946
Cancelation of restricted stock	(1,113)	$ (1,113)
Cancelation of restricted stock (in shares)		(68,000)
Net gain (loss) on pension benefit obligation, net	(1,615)			(1,615)
Currency translation, net	(18,996)				(18,996)
Foreign currency hedge, net	(10)					$ (10)
Interest rate hedge, net	81							$ 81
Net income	70,119								70,119
Ending Balance at Dec. 31, 2014	294,219	$ 243,255	(8,224)	(2,673)	(23,060)	(10)			84,931
Ending Balance (in shares) at Dec. 31, 2014		35,697,000
Exercise of Common Stock options for cash	$ 9,273	$ 12,146	(2,873)
Exercise of Common Stock options for cash (in shares)	571,723	571,000
Tax benefit from Exercises of Common Stock options	$ 6,681		6,681
Common Stock issued to Board of Directors and employees	3,734	$ 3,734
Common Stock issued to Board of Directors and employees (in shares)		108,000
Stock option compensation	3,025		3,025
Cancelation of restricted stock	(2,216)	$ (2,216)
Cancelation of restricted stock (in shares)		(54,000)
Net gain (loss) on pension benefit obligation, net	613			613
Currency translation, net	(26,212)		109		(26,321)
Foreign currency hedge, net	10					10
Commodity hedge, net	(229)						$ (229)
Net income	95,393								95,393
Ending Balance at Dec. 31, 2015	$ 384,291	$ 256,919	(1,282)	(2,060)	(49,381)		(229)		180,324
Ending Balance (in shares) at Dec. 31, 2015	36,321,775	36,322,000
Exercise of Common Stock options for cash	$ 1,438	$ 1,939	(501)
Exercise of Common Stock options for cash (in shares)	112,875	113,000
Tax benefit from Exercises of Common Stock options	$ 7,509		7,509
Common Stock issued to Board of Directors and employees	4,589	$ 4,589
Common Stock issued to Board of Directors and employees (in shares)		137,000
Stock option compensation	4,597		4,597
Cancelation of restricted stock	(1,196)	$ (1,196)
Cancelation of restricted stock (in shares)		(38,000)
Net gain (loss) on pension benefit obligation, net	(490)			(490)
Currency translation, net	(16,381)				(16,381)
Foreign currency hedge, net	(1,020)					(1,020)
Commodity hedge, net	470						470
Net income	76,598								76,598
Ending Balance at Dec. 31, 2016	$ 460,405	$ 262,251	$ 10,323	$ (2,550)	$ (65,762)	$ (1,020)	$ 241		$ 256,922
Ending Balance (in shares) at Dec. 31, 2016	36,534,464	36,534,000