Other Comprehensive Income - Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Pre-Tax Amount
Change in unrealized gains/losses on securities available-for-sale	$ 5,401		$ (12,061)		$ 9,876		$ (13,829)
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	(40)	[1]	0	[1]	(41)	[1]	(2)	[1]
Adjustment to funded status of employee benefit plans	211		598		423		1,196
Other Comprehensive Income (Loss)	5,572		(11,463)		10,258		(12,635)
Tax (Expense) Benefit
Change in unrealized gains/losses on securities available-for-sale	(1,891)		4,221		(3,457)		4,840
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	15	[1]	0	[1]	15	[1]	1	[1]
Adjustment to funded status of employee benefit plans	(74)		(210)		(148)		(419)
Other Comprehensive Income (Loss)	(1,950)		4,011		(3,590)		4,422
Net of Tax Amount
Change in unrealized gains/losses on securities available-for-sale	3,510		(7,840)		6,419		(8,989)
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	(25)	[1]	0	[1]	(26)	[1]	(1)	[1]
Adjustment to funded status of employee benefit plans	137		388		275		777
Other Comprehensive Income (Loss)	$ 3,622		$ (7,452)		$ 6,668		$ (8,213)

[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.