Accumulated Other Comprehensive Loss - Summary of Tax Benefit (Expense) for Various Components of Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Tax expense (benefit) associated with changes in:
Unrealized holding losses/gains on marketable securities	$ 12	$ 37	$ (104)	$ (22)
Fair value of cash flow hedges	142	137	258	0
Tax expense (benefit) associated with reclassification adjustments:
Amortization of unrecognized employee benefit costs	(769)	(701)	(1,575)	(1,406)
Realized gains from sale of marketable securities	17	4	19	15
Realized losses/gains from settlement of cash flow hedges	$ (35)	$ 16	$ (39)	$ (59)

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- Definition

Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

+ References

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-Publisher FASB

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- Definition

Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount of tax (expense) benefit of reclassification adjustment from accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans.

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No definition available.

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Amount of tax expense (benefit), before reclassification adjustments, related to increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

+ References

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Amount of tax expense (benefit) before reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities.

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-Publisher FASB

-Name Accounting Standards Codification

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