Segment Information - Accounts Receivable (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 D [Domain] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Entity-Wide Revenue, Major Customer, Percentage					18.70%
Customer C [Domain]
Concentration Risk [Line Items]
Entity-Wide Revenue, Major Customer, Percentage		17.70%
Customer C [Domain] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Entity-Wide Revenue, Major Customer, Percentage					14.50%
Customer B [Domain]
Concentration Risk [Line Items]
Entity-Wide Revenue, Major Customer, Percentage	32.60%	30.30%	34.60%	23.10%
Customer B [Domain] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Entity-Wide Revenue, Major Customer, Percentage			27.50%		19.10%
Customer A [Domain]
Concentration Risk [Line Items]
Entity-Wide Revenue, Major Customer, Percentage				25.50%