Goodwill and Other Intangible Assets - Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Goodwill, Beginning balance	$ 2,882	$ 1,387
Acquisitions	113	1,602
Dispositions	(35)
Reclassifications		(75)
Other (primarily Fx)	(11)	(32)
Goodwill, Ending balance	2,949	2,882
Ratings
Goodwill [Roll Forward]
Goodwill, Beginning balance	114	122
Acquisitions	0	0
Dispositions	0
Reclassifications		0
Other (primarily Fx)	(5)	(8)
Goodwill, Ending balance	109	114
Market and Commodities Intelligence
Goodwill [Roll Forward]
Goodwill, Beginning balance	2,392	889
Acquisitions	106	1,602
Dispositions	(35)
Reclassifications		(75)
Other (primarily Fx)	(6)	(24)
Goodwill, Ending balance	2,457	2,392
Indices
Goodwill [Roll Forward]
Goodwill, Beginning balance	376	376
Acquisitions	7	0
Dispositions	0
Reclassifications		0
Other (primarily Fx)	0	0
Goodwill, Ending balance	$ 383	$ 376