Pensions and Other Postretirement Benefits - Schedule of Amounts Included in Accumulated Other Comprehensive Income Expected To Be Recognized In Net Periodic Benefit Costs (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Pension Benefits
Schedule of Pension and Other Postretirement Benefits Recognized in Accumulated Other Comprehensive Income (Loss) [Line Items]
Loss recognition	$ 15,937
Prior service cost recognition	66
Transition obligation recognition	2
Other Benefits
Schedule of Pension and Other Postretirement Benefits Recognized in Accumulated Other Comprehensive Income (Loss) [Line Items]
Loss recognition	320
Prior service cost recognition	(335)
Transition obligation recognition	$ 0