Components of Net Periodic Pension Cost (Detail) - Pension Plans, Defined Benefit - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Service cost, net of employee contributions	$ 7.1	$ 6.7	$ 22.1	$ 20.2
Interest cost	5.2	5.4	15.1	15.9
Expected return on plan assets	(7.9)	(7.2)	(23.5)	(20.8)
Amortization	3.1	2.6	8.9	7.5
Net periodic pension cost	$ 7.5	$ 7.5	$ 22.6	$ 22.8