Description of Business and Summary of Significant Accounting Policies (Segment Reporting) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) ProductService_Groups	Jun. 30, 2017 USD ($)
Accounting Policies [Abstract]
Total revenue, international percentage			57.80%	36.90%
Number of product/service groups | ProductService_Groups			4
Segment Reporting Information [Line Items]
Operating revenue	$ 124,626	$ 87,387	$ 232,856	$ 166,490
Exchanges [Member]
Segment Reporting Information [Line Items]
Operating revenue	101,581	60,373	183,439	112,987
Broker Systems [Member]
Segment Reporting Information [Line Items]
Operating revenue	3,696	3,595	7,306	7,383
RCS [Member]
Segment Reporting Information [Line Items]
Operating revenue	19,007	22,663	41,274	44,515
Carrier Systems [Member]
Segment Reporting Information [Line Items]
Operating revenue	$ 342	$ 756	$ 837	$ 1,605