Employee Benefit Plans (Detail) - Assumed Average Annual Rate of Increase in the Per Capita Cost of Covered Benefits	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Post-Retirement Benefit Plan Pre-Age 65 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Health care cost trend rate	8.00%	8.00%
Ultimate trend rate	5.00%	5.00%
Year rate reaches ultimate trend rate	2027	2024
Post-Retirement Benefit Plan Age 65 and Older [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Health care cost trend rate	6.50%	8.00%
Ultimate trend rate	5.00%	5.00%
Year rate reaches ultimate trend rate	2021	2024