Employer Sponsored Benefit Plans - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Cost of sales	$ 152,153	$ 124,989
Selling, product development and administrative expenses	25,471	25,350
Contributions made by company to domestic pension plan	1,200	$ 1,200
Accounting Standards Update 2017-07
Defined Benefit Plan Disclosure [Line Items]
Cost of sales	100
Selling, product development and administrative expenses	100
Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions during remainder of fiscal year	3,000
Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions during remainder of fiscal year	$ 4,000