Accumulated Other Comprehensive Income (Loss) (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Amounts reclassified out of accumulated other comprehensive loss
Cost of products sold (excluding depreciation)	$ (94,057)	$ (102,456)	$ (186,472)	$ (196,282)
Restructuring	18		42
Income before income tax provision	19,779	16,089	33,872	28,001
Tax (expense) or benefit	(6,809)	(5,205)	(11,088)	(9,379)
Net income	12,970	10,884	22,784	18,622
Amount Reclassified from Accumulated Other Comprehensive Loss
Amounts reclassified out of accumulated other comprehensive loss
Net income			(183)
Gains and losses on cash flow hedges | Amount Reclassified from Accumulated Other Comprehensive Loss
Amounts reclassified out of accumulated other comprehensive loss
Income before income tax provision			24
Tax (expense) or benefit			(19)
Net income			5
Gains and losses on cash flow hedges | Amount Reclassified from Accumulated Other Comprehensive Loss | Foreign Exchange Contracts
Amounts reclassified out of accumulated other comprehensive loss
Cost of products sold (excluding depreciation)			430
Gains and losses on cash flow hedges | Amount Reclassified from Accumulated Other Comprehensive Loss | Natural Gas Contracts
Amounts reclassified out of accumulated other comprehensive loss
Cost of products sold (excluding depreciation)			(406)
Pension Benefit Adjustments | Amount Reclassified from Accumulated Other Comprehensive Loss
Amounts reclassified out of accumulated other comprehensive loss
Prior-service costs			(38)
Actuarial losses			(1,920)
Income before income tax provision			(1,958)
Tax (expense) or benefit			738
Net income			(1,220)
Foreign Currency Translation Adjustments | Amount Reclassified from Accumulated Other Comprehensive Loss
Amounts reclassified out of accumulated other comprehensive loss
Restructuring			1,032
Income before income tax provision			1,032
Net income			$ 1,032