Basis of Presentation - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gain (loss) on disposition of assets	$ 383	$ 0	$ (942)
Selling, general and administrative expenses	42,540	40,012		$ 83,137	$ 74,580
Other operating (income) expense, net		0		3,974	942
Other income (expense), net	$ (34)	260		$ 32	1,379
Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Selling, general and administrative expenses		$ (400)			(800)
Other income (expense), net					$ 400