Other Comprehensive Income - Other Comprehensive Income (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
Pre-Tax Amount
Change in unrealized gains/losses on securities available-for-sale	$ (2,032)		$ 335		$ 7,844		$ (13,494)
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	0	[1]	(3)	[1]	(41)	[1]	(5)	[1]
Adjustment to funded status of employee benefit plans	269		631		692		1,827
Other Comprehensive Income (Loss)	(1,763)		963		8,495		(11,672)
Tax (Expense) Benefit
Change in unrealized gains/losses on securities available-for-sale	712		(117)		(2,746)		4,723
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	0	[1]	1	[1]	15	[1]	2	[1]
Adjustment to funded status of employee benefit plans	(94)		(220)		(242)		(639)
Other Comprehensive Income (Loss)	618		(336)		(2,973)		4,086
Net of Tax Amount
Change in unrealized gains/losses on securities available-for-sale	(1,320)		218		5,098		(8,771)
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	0	[1]	(2)	[1]	(26)	[1]	(3)	[1]
Adjustment to funded status of employee benefit plans	175		411		450		1,188
Other Comprehensive Income (Loss)	$ (1,145)		$ 627		$ 5,522		$ (7,586)

[1] Reclassification adjustments are comprised of realized security gains. The gains have been reclassified out of accumulated other comprehensive income (loss) and have affected certain lines in the Consolidated Statements of Comprehensive Income as follows; the pre-tax amount is included in securities gains-net, the tax expense amount is included in the provision for income taxes and the net of tax amount is included in net income.