GOODWILL AND OTHER INTANGIBLE ASSETS - Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Beginning Balance				$ 3,591.0	$ 3,591.0	$ 3,758.2
Goodwill acquired during year					46.5	52.8
Purchase accounting adjustments					(7.4)	(161.2)
Impairments during the year	$ (65.0)	$ 0.0	$ 0.0	0.0	(65.0)
Write-offs related to disposition and assets held for sale					(7.1)	(7.5)
Changes due to foreign currency fluctuations					46.0	(51.3)
Ending Balance	3,604.0				3,604.0	3,591.0
Domestic and Canada RCS
Goodwill [Roll Forward]
Beginning Balance				2,811.8	2,811.8	2,842.7
Goodwill acquired during year					36.9	41.5
Purchase accounting adjustments					(10.1)	(77.2)
Impairments during the year					0.0
Write-offs related to disposition and assets held for sale					0.0	0.0
Changes due to foreign currency fluctuations					11.6	4.8
Ending Balance	2,850.2				2,850.2	2,811.8
International Regulated and Compliance Services
Goodwill [Roll Forward]
Beginning Balance				498.4	498.4	632.5
Goodwill acquired during year					4.9	8.4
Purchase accounting adjustments					1.2	(78.9)
Impairments during the year					(65.0)
Write-offs related to disposition and assets held for sale					(7.1)	(7.5)
Changes due to foreign currency fluctuations					34.4	(56.1)
Ending Balance	466.8				466.8	498.4
Other
Goodwill [Roll Forward]
Beginning Balance				$ 280.8	280.8	283.0
Goodwill acquired during year					4.7	2.9
Purchase accounting adjustments					1.5	(5.1)
Impairments during the year					0.0
Write-offs related to disposition and assets held for sale					0.0	0.0
Changes due to foreign currency fluctuations					0.0	0.0
Ending Balance	$ 287.0				$ 287.0	$ 280.8