Segment Reporting - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues, less transaction-based expenses	$ 1,144,000	$ 1,143,000	$ 1,178,000	$ 1,164,000	$ 1,138,000	$ 1,078,000	$ 1,129,000	$ 1,154,000	$ 4,629,000	$ 4,499,000	$ 3,338,000
Operating expenses									2,250,000	2,332,000	1,588,000
Operating income	$ 592,000	$ 596,000	$ 609,000	$ 582,000	$ 558,000	$ 474,000	$ 551,000	$ 584,000	2,379,000	2,167,000	1,750,000
Trading and Clearing Segment
Segment Reporting Information [Line Items]
Revenues, less transaction-based expenses									2,128,000	2,102,000	2,062,000
Operating expenses									779,000	825,000	915,000
Operating income									1,349,000	1,277,000	1,147,000
Data and Listings Segment
Segment Reporting Information [Line Items]
Revenues, less transaction-based expenses									2,501,000	2,397,000	1,276,000
Operating expenses									1,471,000	1,507,000	673,000
Operating income									$ 1,030,000	$ 890,000	$ 603,000