Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefit (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	$ 11.9	$ 15.6
Additions for Tax Positions Taken in Prior Years	3.9	3.0
Reductions for Tax Positions Taken in Prior Years	(2.7)	(5.5)
Reductions Resulting from Expiration of Statutes	(0.8)	(1.2)
Ending Balance	$ 12.3	$ 11.9