Estimated Amount Amortized from Accumulated Other Comprehensive Income Into Net Periodic Benefit Cost (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Transition obligation	$ (1)
Prior service cost	17
Net actuarial loss	44
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year, Total	$ 60