Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue from Contract with Customer [Abstract]
Percentage of total revenue accounted for percentage-of-completion revenue, less than	0.10%	0.10%	0.10%	0.10%
Product sales as a percentage of total revenue	95.00%	95.00%	95.00%	95.00%
Disaggregation of Revenue [Line Items]
Revenue	$ 59,086	$ 85,177	$ 119,602	$ 165,131
Cost of revenue (excluding depreciation and amortization)	46,738	58,574	92,439	110,199
Products
Disaggregation of Revenue [Line Items]
Revenue	57,630	83,835	116,881	162,350
Cost of revenue (excluding depreciation and amortization)	45,511	57,052	90,028	107,741
Services
Disaggregation of Revenue [Line Items]
Revenue	1,456	1,342	2,721	2,781
Cost of revenue (excluding depreciation and amortization)	$ 1,227	$ 1,522	$ 2,411	$ 2,458