Segment, Geographical and Other Revenue Information - Concentration Risk (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2016
Customer Concentration Risk [Member] | Customer A [Member] | Sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	48.00%	38.00%
Customer Concentration Risk [Member] | Customer B [Member] | Sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage		20.00%
Customer Concentration Risk [Member] | Customer C [Member] | Sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage		19.00%
Customer Concentration Risk [Member] | Customer D [Member] | Sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	24.00%
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	46.00%		31.00%
Credit Concentration Risk [Member] | Customer C [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	12.00%		15.00%
Credit Concentration Risk [Member] | Customer E [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk, percentage			16.00%
Credit Concentration Risk [Member] | Customer F [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	13.00%		14.00%