Net Deferred Tax Asset and Income Taxes (Schedule of Income Tax Rate Reconciliation) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Tax expense at Federal statutory rate	$ 17,805	$ 14,926	$ 12,024
(Decrease) increase in taxes resulting from:
Tax-exempt income	(1,220)	(1,220)	(1,145)
Dividends received deduction	(12)	(32)	(48)
BOLI	(857)	(678)	(660)
Federal tax credits	(364)	(364)	(231)
State income tax expense, net of federal income tax benefit	358	315	229
Other	88	(25)	133
Total income tax expense	$ 15,798	$ 12,922	$ 10,302

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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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 the deduction for dividends paid or received under enacted tax laws.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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The sum of other amounts reflected in the reconciliation of the statutory tax provision (benefit) to the actual tax provision (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, 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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Income Tax Reconciliation, Bank Owned Life Insurance Income (Expense)

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