Annual report pursuant to Section 13 and 15(d)

Amount of Prior Service Cost and Actuarial Loss Included in Accumulated Other Comprehensive Loss that is Expected to Be Recognized in Net Periodic Benefit Cost (Parenthetical) (Detail)

v2.4.0.6
Amount of Prior Service Cost and Actuarial Loss Included in Accumulated Other Comprehensive Loss that is Expected to Be Recognized in Net Periodic Benefit Cost (Parenthetical) (Detail) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2011
Pension Benefits
 
Defined Benefit Plan Disclosure [Line Items]  
Actuarial loss, taxes $ 5.8
Prior service cost, taxes 0.3
Other Benefits
 
Defined Benefit Plan Disclosure [Line Items]  
Actuarial loss, taxes 0.4
Prior service cost, taxes $ (0.1)