Amounts Recognized in Consolidated Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	$ (108.5)	$ (252.7)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Current benefit payment liability	(0.8)	(0.8)
Accrued benefit liability	(77.7)	(184.9)
Net amount recognized	(78.5)	(185.7)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Current benefit payment liability	(3.5)	(5.5)
Accrued benefit liability	(30.7)	(67.8)
Net amount recognized	$ (34.2)	$ (73.3)