Concentration of Credit Risk (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Net accounts receivable | Customer concentration | Company A
Concentration Risk [Line Items]
Risk concentration			11.00%
Net accounts receivable | Customer concentration | Company B
Concentration Risk [Line Items]
Risk concentration			10.00%
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	13.00%
Total revenue | Customer concentration | Company B
Concentration Risk [Line Items]
Risk concentration	12.00%
Total revenue | Customer concentration | Company C
Concentration Risk [Line Items]
Risk concentration	11.00%
Total revenue | Customer concentration | Company D
Concentration Risk [Line Items]
Risk concentration		22.00%		13.00%
Total revenue | Customer concentration | Company E
Concentration Risk [Line Items]
Risk concentration		21.00%		12.00%
Total revenue | Customer concentration | Company F
Concentration Risk [Line Items]
Risk concentration		19.00%		11.00%
Total revenue | Customer concentration | Company G
Concentration Risk [Line Items]
Risk concentration		15.00%
Total revenue | Customer concentration | Company H
Concentration Risk [Line Items]
Risk concentration				31.00%
Total revenue | Customer concentration | Company I
Concentration Risk [Line Items]
Risk concentration				15.00%
Financial institution A | Cash and cash equivalents | Concentration of credit risk
Concentration Risk [Line Items]
Risk concentration			58.00%		82.00%
Financial institution B | Cash and cash equivalents | Concentration of credit risk
Concentration Risk [Line Items]
Risk concentration			28.00%		12.00%