Accumulated Other Comprehensive Loss - Net Change and Ending Balances for Various Components of Accumulated Other Comprehensive Loss (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			$ (45,865)	$ (82,375)
Net Change	(2,358)	4,773	5,733	4,602
Ending balance	(40,132)	(77,773)	(40,132)	(77,773)
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			277	(1,543)
Net Change			(1,945)	97
Ending balance	(1,668)	(1,446)	(1,668)	(1,446)
Unrecognized Employee Benefit Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(47,462)	(81,783)
Net Change			7,749	4,331
Ending balance	(39,713)	(77,452)	(39,713)	(77,452)
Unrealized Holding Gains on Marketable Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			1,007	633
Net Change			54	245
Ending balance	1,061	878	1,061	878
Realized (Gains) Losses from Settlement of Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			313	318
Net Change			(125)	(71)
Ending balance	$ 188	$ 247	$ 188	$ 247