Employee Benefits - Asset Target Allocations Prescribed by Pension Funds' Investment Policies (Detail)	12 Months Ended
	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Total Target Allocation	100.00%
Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Target Allocation	46.00%
Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Target Allocation	28.00%
Convertible securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Target Allocation	5.00%
Other assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Target Allocation	21.00%