Summary of Pre-Tax Net Actuarial Losses and Prior Service Cost Recognized in Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Pension Plans
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Net actuarial losses	$ 84.6	$ 142.7
Net prior service costs	(3.3)	(4.0)
Total recognized in AOCI- pretax	(87.9)	(146.7)
Other Retirement Plans
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Net actuarial losses	2.4	6.0
Net prior service costs	0	0
Total recognized in AOCI- pretax	$ (2.4)	$ (6.0)