Accumulated Other Comprehensive Loss - Summary of Income Tax Expense (Benefit) Associated with Various Components of Other Comprehensive Income (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
Tax expense (benefit) associated with changes in:
Unrecognized employee benefit costs	$ 0	$ 0	$ (2,739)	$ 0
Unrealized holding losses/gains on marketable securities	37	(55)	(60)	(159)
Fair value of cash flow hedges	40	(93)	107	165
Tax expense (benefit) associated with reclassification adjustments:
Amortization of unrecognized employee benefit costs	(462)	(774)	(1,404)	(2,349)
Realized gains from sale of marketable securities	13	9	32	28
Realized gains/losses from settlement of cash flow hedges	$ 8	$ (87)	$ (33)	$ (126)