Business Segment, Geographic and Major Customer Information - Major Customers (Details) - Customer Concentration Risk - Sales	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Customer A
Segment Reporting Information [Line Items]
Percentage of revenue by major customers	13.30%	12.50%	12.90%	17.90%
Customer B
Segment Reporting Information [Line Items]
Percentage of revenue by major customers	8.80%	14.80%	9.60%	13.50%