Amounts Recognized In Accumulated Other Comprehensive Loss (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Retirement Plans [Line Items]
Net loss	$ 23.4	$ 38.9
After tax amount	113.1	106.3	85.2	91.2
Pension Plans, Defined Benefit
Retirement Plans [Line Items]
Net loss	178.2	165.7
Prior service credit	(5.1)	(5.4)
Before tax amount	173.1	160.3
After tax amount	$ 111.1	$ 104.2