Retirement Benefit Obligations - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions to benefit plan	$ 900,000
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Contributions to benefit plan	0
Supplemental Employee Retirement Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Contributions to benefit plan	13,000
Expected additional contribution to SERP plan	$ 40,000