Postretirement Benefit Plans - Fair Value Changes Within Asset Categories for which Fair Value Measurements Use Significant Unobservable Inputs Level 3 (Detail) (Insurance Contracts [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Insurance Contracts [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 2,426	$ 2,437
Sale proceeds (benefit payments)	(178)	(175)
Change in unrealized gain	135	120
Foreign exchange impact	(142)	44
Ending balance	$ 2,241	$ 2,426