Significant Customers & Concentration of Credit Risk (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Concentration Risk [Line Items]
Unbilled accounts receivable	$ 107,640		$ 119,335
Single Customer
Concentration Risk [Line Items]
Unbilled accounts receivable	14,600
Single Financial Services Customer
Concentration Risk [Line Items]
Unbilled accounts receivable	$ 25,300
Revenue | Single Customer
Concentration Risk [Line Items]
Concentration risk percentage	15.00%	13.00%
Revenue | Single Financial Services Customer
Concentration Risk [Line Items]
Concentration risk percentage	14.00%	14.00%
Revenue | Automotive Industry
Concentration Risk [Line Items]
Concentration risk percentage	22.00%	22.00%
Revenue | Financial & Insurance Industry [Member]
Concentration Risk [Line Items]
Concentration risk percentage	20.00%	20.00%
Accounts Receivable | Single Customer
Concentration Risk [Line Items]
Concentration risk percentage	14.00%
Accounts Receivable | Single Financial Services Customer
Concentration Risk [Line Items]
Concentration risk percentage	17.00%