Weighted - Average Assumptions Used to Determine Net Periodic Benefit Cost (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Benefits
Schedule of Net Periodic Benefit Costs Weighted Average Assumptions [Line Items]
Expected long-term return on plan assets	7.75%	7.75%	7.50%
Rate of compensation increase	4.25%	4.75%	4.75%
Pension Benefits | Minimum
Schedule of Net Periodic Benefit Costs Weighted Average Assumptions [Line Items]
Discount rate	3.90%	4.70%	5.40%
Pension Benefits | Maximum
Schedule of Net Periodic Benefit Costs Weighted Average Assumptions [Line Items]
Discount rate	4.25%	4.90%	5.75%
Other Postretirement Benefits | Minimum
Schedule of Net Periodic Benefit Costs Weighted Average Assumptions [Line Items]
Discount rate	3.90%	4.60%	5.25%
Other Postretirement Benefits | Maximum
Schedule of Net Periodic Benefit Costs Weighted Average Assumptions [Line Items]
Discount rate	4.00%	4.80%	5.50%