Income Taxes (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of tax expense at the Federal statutory tax rate
Tax expense at the Federal statutory tax rate	$ 27,651	$ 24,744	$ 22,976
Increase (decrease) in tax expense from:
Tax-exempt income, net	(783)	(904)	(648)
Modified endowment life contracts	(870)	(809)	(705)
State tax expense, net of Federal tax benefit	3,652	3,916	3,098
Federal tax credits	(2,455)	(1,227)	(1,914)
Other, net	(91)	(644)	530
Total income taxes	$ 27,104	$ 25,076	$ 23,337

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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 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 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 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 tax credits generated or utilized under enacted tax laws during the period.

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