Amounts in Accumulated Other Comprehensive Loss Expected to be Recognized Next Fiscal Year (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 41.0
Net prior service credit
Total	41.0
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss
Net prior service credit	(26.9)
Total	$ (26.9)