Activity related to Unrecognized Tax Benefit (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Schedule of Unrecognized Tax Benefits [Line Items]
Unrecognized tax benefits	$ 145.3	$ 88.9
Acquisitions	7.7	5.2
Tax positions taken during the current period	77.9	48.1
Tax positions taken during a prior period	(12.5)	3.7
Settlements with taxing authorities	(8.7)	(0.5)
Other	(0.7)	(0.1)
Unrecognized tax benefits, December 31,	$ 209.0	$ 145.3