Concentration of Credit Risk (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total revenue | One Customer
Concentration Risk [Line Items]
Risk concentration	27.00%	28.00%	3.00%
Customer concentration | Accounts Receivable | One Customer
Concentration Risk [Line Items]
Risk concentration	10.00%	24.00%
Customer concentration | Total revenue | Customer A
Concentration Risk [Line Items]
Risk concentration		13.00%
Customer concentration | Total revenue | Customer B
Concentration Risk [Line Items]
Risk concentration		18.00%
Customer concentration | Total revenue | Customer C
Concentration Risk [Line Items]
Risk concentration			87.00%
Financial Institution A | Concentration of Credit Risk | Cash and Cash Equivalents
Concentration Risk [Line Items]
Risk concentration	43.00%	82.00%
Financial Institution B | Concentration of Credit Risk | Cash and Cash Equivalents
Concentration Risk [Line Items]
Risk concentration	46.00%	12.00%