Segment, Geographical and Other Revenue Information - Concentration Risk (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Customer Concentration Risk [Member] | Customer A [Member] | Sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	27.00%	27.00%	33.00%	37.00%
Customer Concentration Risk [Member] | Customer B [Member] | Sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	28.00%		24.00%
Customer Concentration Risk [Member] | Customer C [Member] | Sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	10.00%	11.00%	17.00%	11.00%
Customer Concentration Risk [Member] | Customer D [Member] | Sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	15.00%	29.00%	11.00%	18.00%
Customer Concentration Risk [Member] | Customer E [Member] | Sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage		10.00%
Credit Concentration Risk [Member] | Customer A [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk, percentage			45.00%		31.00%
Credit Concentration Risk [Member] | Customer B [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk, percentage			10.00%
Credit Concentration Risk [Member] | Customer C [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk, percentage					16.00%
Credit Concentration Risk [Member] | Customer D [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk, percentage			10.00%		15.00%
Credit Concentration Risk [Member] | Customer F [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk, percentage					14.00%
Credit Concentration Risk [Member] | Customer G [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk, percentage			11.00%