Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 60,516	$ 79,954
Products	44,514	50,691
Services	1,187	934
Cost of revenue (excluding depreciation and amortization)	$ 45,701	$ 51,625
Percentage of total revenue accounted for percentage-of-completion revenue, less than	0.10%	0.10%
Product sales as a percentage of total revenue	95.00%	95.00%
Products
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 59,250	$ 78,514
Services
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 1,266	$ 1,440