Restructuring - Summary of Restructuring Activity (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost And Reserve [Line Items]
Balance at January 1, 2018		$ 1,188
Charges to expense	$ 2,072	119	$ 7,132
Cash payments		(1,197)
Non-cash utilization		(16)
Balance at September 30, 2018		94
Employee Reduction [Member]
Restructuring Cost And Reserve [Line Items]
Balance at January 1, 2018		1,098
Charges to expense		31
Cash payments		(1,035)
Balance at September 30, 2018		94
Accelerated Depreciation [Member]
Restructuring Cost And Reserve [Line Items]
Charges to expense		16
Non-cash utilization		(16)
Other Exit Costs [Member]
Restructuring Cost And Reserve [Line Items]
Balance at January 1, 2018		90
Charges to expense		72
Cash payments		$ (162)