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	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income tax expense (benefit) associated with changes in:
Unrecognized employee benefit costs	$ (15,890)	$ 5,256	$ 12,958
Unrealized holding gains/losses on marketable securities	(232)	(80)	15
Fair value of cash flow hedges	149	(61)	427
Income tax expense (benefit) associated with reclassification adjustments:
Amortization of unrecognized employee benefit costs	(3,156)	(3,547)	(2,066)
Realized gains/losses from sale of marketable securities	30	42	(7)
Realized gains/losses from settlement of cash flow hedges	$ (146)	$ (67)	$ 230