The Amounts in AOCI That are Expected to be Amortized as Net Expense (Income) During Next Fiscal Year (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Pension Plans, Defined Benefit
Schedule of Pension and Other Postretirment Benefits Expected Benefit Payments [Line Items]
Amount of net prior service cost	$ (139)
Amount of net loss	5,144
Other Postretirement Benefit Plans, Defined Benefit
Schedule of Pension and Other Postretirment Benefits Expected Benefit Payments [Line Items]
Amount of net prior service cost	0
Amount of net loss	$ 352