Restructuring and Impairment Charges - Narrative (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017 USD ($) Segment	Sep. 30, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Number of operating segments (allocated to) | Segment	3
Arizona
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 600	$ 2,400
Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		361
Expected cost to be paid	1,100	$ 1,100
Brightvolt, Inc.
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	$ 300