Schedule of Amounts Recognized in Accumulated Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Pension and Other Postretirement Benefits Recognized in Accumulated Other Comprehensive Income (Loss) [Line Items]
Deferred taxes	$ (12,192)	$ (11,582)	$ (12,297)
Defined Benefit Pension Plans
Schedule of Pension and Other Postretirement Benefits Recognized in Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service cost	493	656
Deferred taxes	380	321
Total recognized in other comprehensive income, net of tax	873	977
Post-Retirement Benefit Plans
Schedule of Pension and Other Postretirement Benefits Recognized in Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service cost	(2,829)	(3,427)
Total recognized in other comprehensive income before tax	(2,829)	(3,427)
Deferred taxes	(664)	(445)
Total recognized in other comprehensive income, net of tax	$ (3,493)	$ (3,872)