Accumulated Other Comprehensive Income - Component of Accumulated Other Comprehensive Income (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
Equity [Abstract]
Unrealized gains on investment securities beginning balance	$ 4,143	$ 3,998	$ 4,524	$ 3,926
Unrealized gains on investment securities, Current period charge	(1,827)	375	(2,208)	447
Unrealized gains on investment securities ending balance	2,316	4,373	2,316	4,373
Defined benefit plans beginning balance	(4,814)	(4,204)	(4,814)	(4,204)
Defined benefit plans, Current period charge
Defined benefit plans ending balance	(4,814)	(4,204)	(4,814)	(4,204)
Beginning balance	(671)	(206)	(290)	(278)
Accumulated other comprehensive income loss, Current period change	(1,827)	375	(2,208)	447
Ending balance	$ (2,498)	$ 169	$ (2,498)	$ 169

Accumulated appreciation or loss, net of tax, in value of the total of available-for-sale securities at the end of an accounting period.

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The total of net gain (loss), prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in accumulated other comprehensive income associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost.

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

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-Name Statement of Financial Accounting Standard (FAS)

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- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References

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