Schedule of Effective Income Tax Rate Reconciliation (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Provision Income Tax [Line Items]
Statutory Rate Times Pre-tax Income	$ 12,153	$ 9,791	$ 6,660
Add (Subtract) the Tax Effect of:
Income from Tax-exempt Loans and Investments	(1,007)	(780)	(533)
State Income Tax, Net of Federal Tax Effect	494	99	105
General Business Tax Credits	(547)	(370)	(365)
Company Owned Life Insurance	(341)	(385)	(282)
Gain on American Community Bancorp, Inc, Stock	0	(366)	0
Other Differences	(83)	(263)	38
Total Income Taxes	$ 10,669	$ 7,726	$ 5,623

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to pretax Income or Loss from continuing operations; income tax expense or benefit may include interest and penalties on tax uncertainties based on the entity's accounting policy.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to other deductions received under enacted tax laws not otherwise listed in the existing taxonomy.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to nondeductible life insurance premiums under enacted tax laws.

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The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to state and local income tax expense or benefit.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to income that is exempt from income taxes under enacted tax laws.

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