Significant Accounting Policies - Reclassification (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales	$ 149,000	$ 142,473
Selling, general and administrative expenses	31,523	33,332
Other income (expense)	$ (2,107)	(2,786)
Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales		143,356
Selling, general and administrative expenses		32,975
Other income (expense)		(2,260)
Accounting Standards Update 2017-07 | Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales		(883)
Selling, general and administrative expenses		357
Other income (expense)		$ (526)