Segment Reporting - Revenue by Product Group (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues
Total Revenues	$ 121,581	$ 120,610	$ 242,416	$ 245,278
Execution Services
Revenues
Total Revenues	86,797	83,408	173,084	173,201
Workflow Technology
Revenues
Total Revenues	23,352	23,094	46,452	46,687
Analytics
Revenues
Total Revenues	11,057	11,345	22,200	22,280
Corporate
Revenues
Total Revenues	$ 375	$ 2,763	$ 680	$ 3,110

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration