Changes in Accumulated Other Comprehensive Income by Component (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ (14,571)	$ (11,883)	$ (10,698)
Net sales	1,436,499	1,230,754	1,193,975
Income before income taxes	195,699	182,621	157,946
Tax benefit	(136,284)	(47,020)	(36,566)
Total reclassifications in the period	59,415	135,601	$ 121,380
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications in the period	(7,914)	(7,667)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains and Losses on Cash Flow Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(787)	(618)
Tax benefit	257	221
Income from continuing operations	(530)	(397)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains and Losses on Cash Flow Hedges | Interest Rate Contracts [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	(545)	(557)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains and Losses on Cash Flow Hedges | Foreign Exchange Contracts [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net sales	(242)	(61)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Pension and Other Postretirement Benefit Items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(11,166)	(11,163)
Tax benefit	3,782	3,893
Income from continuing operations	(7,384)	(7,270)
Amortization of prior-service credits, net	(378)	163
Amortization of actuarial losses	(10,833)	(11,326)
Curtailment gain	187	0
Settlement loss	$ (142)	$ 0