Significant Customers & Concentration of Credit Risk (Details Textual) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Concentration Risk [Line Items]
Unbilled accounts receivable		$ 110,122		$ 119,335
Single Customer
Concentration Risk [Line Items]
Unbilled accounts receivable		18,400
Single Financial Services Customer
Concentration Risk [Line Items]
Unbilled accounts receivable		$ 23,100
Revenue | Single Customer
Concentration Risk [Line Items]
Concentration risk percentage	14.00%	15.00%
Revenue | Single Financial Services Customer
Concentration Risk [Line Items]
Concentration risk percentage		14.00%	13.00%
Revenue | Automotive Industry
Concentration Risk [Line Items]
Concentration risk percentage		23.00%	23.00%
Revenue | Financial & Insurance Industry [Member]
Concentration Risk [Line Items]
Concentration risk percentage		20.00%	19.00%
Accounts Receivable | Single Customer
Concentration Risk [Line Items]
Concentration risk percentage		17.00%
Accounts Receivable | Single Financial Services Customer
Concentration Risk [Line Items]
Concentration risk percentage		15.00%