Segment Reporting - Revenue by Product Group (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Total Revenues	$ 131,484
Revenue in Analytics for functionality but not a separate performance obligation from products and services provided by Workflow Technology and Execution Services	500
Execution Services
Revenues
Total Revenues	94,356
Workflow Technology
Revenues
Total Revenues	26,575
Analytics
Revenues
Total Revenues	10,039
Corporate
Revenues
Total Revenues	$ 514
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenues
Total Revenues		$ 120,835
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Execution Services
Revenues
Total Revenues		86,287
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Workflow Technology
Revenues
Total Revenues		23,100
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Analytics
Revenues
Total Revenues		11,143
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Corporate
Revenues
Total Revenues		$ 305