Components of Pension Expense (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Schedule of Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets [Line Items]
Service cost	$ 17.0	$ 18.9
Interest on projected benefit obligation	23.0	20.3
Expected return on assets	(32.0)	(29.9)
Amortization of prior service costs	0.3	0.3
Recognized actuarial loss	5.2	10.9
Net pension expense	$ 13.5	$ 20.5