Amounts Recognized in Other Comprehensive Income (Loss) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Total	$ 390.9	$ (919.0)	$ 285.1
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Amortization of Net actuarial loss	31.9
Amortization of Net prior service credit	0
Amounts arising during the period, Net actuarial	(456.0)
Amounts arising during the period, Net prior service credit	0
Amounts arising during the period, Settlements	95.7
Amounts arising during the period, Foreign currency loss	1.2
Total	(327.2)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Amortization of Net actuarial loss	0
Amortization of Net prior service credit	(25.8)
Amounts arising during the period, Net actuarial	(43.8)
Amounts arising during the period, Net prior service credit	5.7
Amounts arising during the period, Settlements	0
Amounts arising during the period, Foreign currency loss	0.2
Total	$ (63.7)