Items to be Recognized in 2014 as Component of Net Periodic Cost (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013
Pension Benefits [Member]
Items to be recognized in 2014 as a component of net periodic cost
Net actuarial loss (gain)	$ 826
Prior service cost (credit)	1,189
Net periodic cost (credit) to be recorded in 2014	2,015
Other Postretirement Benefits [Member]
Items to be recognized in 2014 as a component of net periodic cost
Net actuarial loss (gain)	(330)
Prior service cost (credit)	(2,854)
Net periodic cost (credit) to be recorded in 2014	$ (3,184)

Amount included in accumulated other comprehensive income (AOCI) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position, including gain (loss), prior service cost (credit), and transition asset (obligation).

No definition available.

Name:	us-gaap_DefinedBenefitPlanAmountToBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration