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Income Taxes (Income Tax Expense Differed From Statutory Federal Income Tax Rate) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
Statutory federal tax rate	35.00%	35.00%	35.00%
Tax exempt interest income	(5.60%)	(5.60%)	(6.10%)
Tax credits and adjustments	(6.70%)	0.30%	(0.70%)
Non-taxable earnings on company owned life insurance	(1.40%)	(2.20%)	(1.80%)
State taxes, net of federal tax benefit	1.10%	0.80%	0.70%
Nondeductible expenses	0.30%	0.20%	0.30%
Goodwill and contingent consideration adjustments	0.30%	(0.90%)	(0.30%)
Other, net	(0.10%)	0.10%
Effective tax rate	22.90%	27.70%	27.10%

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Effective Income Tax Rate Reconciliation Non Taxable Earnings On Company Owned Life Insurance

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to nondeductible expenses.

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