Weighted - Average Assumptions Used to Determine Benefit Obligations (Detail)	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	4.25%	4.25%
Pension Benefits | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.70%	3.90%
Pension Benefits | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.90%	4.25%
Other Postretirement Benefits | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.60%	3.90%
Other Postretirement Benefits | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.70%	4.00%