v2.4.0.6
Postretirement Benefit Plans - Summary of Weighted Average Assumptions Used to Calculate Projected Benefit Obligations (Detail)
Dec. 31, 2012
Dec. 31, 2011
Pension Plans, Postretirement and Other Employee Benefits [Line Items]    
Discount rate 3.50% 4.40%
Rate of compensation increase 2.40% 3.10%