Schedule of Target Assets Allocation (Detail)	12 Months Ended
	Dec. 31, 2013
Passive And Active Fixed Income | Barclays U.S. Long Government/Credit Bond Index | Fixed Income Funds
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target assets allocation percentage	90.00%
Equity (Large Cap) | S&P 500 Stock Index | Equity Securities
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target assets allocation percentage	7.00%
International Equity | MSCI EAFE Index | Equity Securities
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target assets allocation percentage	3.00%