Accumulated Other Comprehensive Loss - Net Change and Ending Balances for Various Components of Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Loss (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (82,375)	$ (79,290)
Net Change	(171)	3,215
Ending balance	(82,546)	(76,075)
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1,543)	(4,736)
Net Change	(2,750)	594
Ending balance	(4,293)	(4,142)
Unrecognized Employee Benefit Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(81,783)	(75,225)
Net Change	2,787	2,517
Ending balance	(78,996)	(72,708)
Unrealized Holding Gains on Marketable Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	633	562
Net Change	159	13
Ending balance	792	575
Realized Losses (Gains) from Settlement of Cash Flow Hedges: [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	318	109
Net Change	(367)	91
Ending balance	$ (49)	$ 200