Concentration of Credit 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
Net accounts receivable | Customer concentration | Company A
Concentration Risk [Line Items]
Risk concentration			18.00%
Net accounts receivable | Customer concentration | Company B
Concentration Risk [Line Items]
Risk concentration			13.00%
Net accounts receivable | Customer concentration | Company C
Concentration Risk [Line Items]
Risk concentration					24.00%
Total revenue | Customer concentration | Company A
Concentration Risk [Line Items]
Risk concentration	17.00%
Total revenue | Customer concentration | Company B
Concentration Risk [Line Items]
Risk concentration	18.00%
Total revenue | Customer concentration | Company C
Concentration Risk [Line Items]
Risk concentration	20.00%
Total revenue | Customer concentration | Company D
Concentration Risk [Line Items]
Risk concentration		10.00%		22.00%
Total revenue | Customer concentration | Company E
Concentration Risk [Line Items]
Risk concentration		12.00%
Total revenue | Customer concentration | Company F
Concentration Risk [Line Items]
Risk concentration		16.00%
Total revenue | Customer concentration | Company G
Concentration Risk [Line Items]
Risk concentration		19.00%
Total revenue | Customer concentration | Company H
Concentration Risk [Line Items]
Risk concentration		20.00%		15.00%
Financial institution A | Cash and cash equivalents | Concentration of credit risk
Concentration Risk [Line Items]
Risk concentration			57.00%		82.00%
Financial institution B | Cash and cash equivalents | Concentration of credit risk
Concentration Risk [Line Items]
Risk concentration			31.00%		12.00%
Financial institution C | Cash and cash equivalents | Concentration of credit risk
Concentration Risk [Line Items]
Risk concentration			12.00%