Benefit Plans - Weighted Average Assumptions Used to Determine Benefit Obligations (Detail)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.40%	3.60%	4.50%
Expected long term rate of return on plan assets	7.50%
Expected long term rate of return on plan assets, minimum rate		7.50%	7.50%
Expected long term rate of return on plan assets, maximum rate		7.80%	8.00%
Rate of compensation increase, minimum rate	3.50%	3.50%	4.00%
Rate of compensation increase, maximum rate	5.50%	5.50%	5.50%
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.20%	3.50%	4.30%
Expected long term rate of return on plan assets	5.30%	5.30%	5.30%