Weighted-Average Assumptions used in Measurement of Benefit Obligations and Net Periodic Benefit Expense (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	6.24%
Expected return on plan assets	6.24%
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit Obligation, Discount rate	4.78%	4.24%
Expected return on plan assets	6.24%	6.20%
Benefit Obligation, Rate of compensation increase	4.14%	4.13%
Net periodic benefit expense, Discount rate	4.23%	4.80%
Expected return on plan assets	6.24%	6.20%
Net periodic benefit expense, Rate of compensation increase	4.12%	4.10%
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit Obligation, Discount rate	4.91%	4.18%
Expected return on plan assets	0.00%	0.00%
Benefit Obligation, Rate of compensation increase	0.00%	0.00%
Net periodic benefit expense, Discount rate	4.18%	4.87%
Expected return on plan assets	0.00%	0.00%
Net periodic benefit expense, Rate of compensation increase	0.00%	0.00%