Retirement Plans - Summary of Plan's Weighted Average Asset Allocations (Detail)	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	100.00%	100.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	69.00%	66.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	24.00%	27.00%
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	7.00%	7.00%