Comprehensive Income - Changes in Accumulated Other Comprehensive Income, Net of Tax, by Component (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), balance at beginning of period	$ (46,224)
Other comprehensive income (loss) before reclassifications	(10,200)
Amounts reclassified from accumulated other comprehensive income	(500)
Net current period other comprehensive income (loss)	(10,700)	(1,076)	(11,416)
Accumulated other comprehensive income (loss), balance at end of period	(56,924)	(46,224)
Unrealized Net Gains (Losses) on Securities Available for Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), balance at beginning of period	9,269
Other comprehensive income (loss) before reclassifications	(20,643)
Amounts reclassified from accumulated other comprehensive income	(500)
Net current period other comprehensive income (loss)	(21,143)
Accumulated other comprehensive income (loss), balance at end of period	(11,874)
Non-Credit Related Loss on Debt Securities not Expected to be Sold [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), balance at beginning of period	(8,039)
Other comprehensive income (loss) before reclassifications	1,847
Amounts reclassified from accumulated other comprehensive income
Net current period other comprehensive income (loss)	1,847
Accumulated other comprehensive income (loss), balance at end of period	(6,192)
Unrealized Losses on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), balance at beginning of period	(171)
Other comprehensive income (loss) before reclassifications	(6,415)
Amounts reclassified from accumulated other comprehensive income
Net current period other comprehensive income (loss)	(6,415)
Accumulated other comprehensive income (loss), balance at end of period	(6,586)
Unrecognized Pension and Postretirement Obligations [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), balance at beginning of period	(47,283)
Other comprehensive income (loss) before reclassifications	15,011
Amounts reclassified from accumulated other comprehensive income
Net current period other comprehensive income (loss)	15,011
Accumulated other comprehensive income (loss), balance at end of period	$ (32,272)