GOODWILL AND OTHER INTANGIBLE ASSETS (Changes in Amount of Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Beginning Balance	$ 3,974.3	$ 2,571.0
Acquisitions	92.4	1,456.3
Adjustments to initial purchase price allocation	1.0	(6.4)
Foreign currency translation	116.3	(46.6)
Ending Balance	4,184.0	3,974.3
U.S. Information Solutions
Goodwill [Roll Forward]
Beginning Balance	1,071.3	1,071.3
Acquisitions	0.0	0.0
Adjustments to initial purchase price allocation	0.0	0.0
Foreign currency translation	0.0	0.0
Ending Balance	1,071.3	1,071.3
International
Goodwill [Roll Forward]
Beginning Balance	1,814.6	441.5
Acquisitions	43.9	1,411.6
Adjustments to initial purchase price allocation	1.0	(6.2)
Foreign currency translation	109.9	(32.3)
Ending Balance	1,969.4	1,814.6
Workforce Solutions
Goodwill [Roll Forward]
Beginning Balance	952.1	907.6
Acquisitions	0.0	44.7
Adjustments to initial purchase price allocation	0.0	(0.2)
Foreign currency translation	0.0	0.0
Ending Balance	952.1	952.1
Global Consumer Solutions
Goodwill [Roll Forward]
Beginning Balance	136.3	150.6
Acquisitions	48.5	0.0
Adjustments to initial purchase price allocation	0.0	0.0
Foreign currency translation	6.4	(14.3)
Ending Balance	$ 191.2	$ 136.3