Federal Income Taxes (Reconciliation) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Reconciliation [Abstract]
Income tax expense at statutory rate of 35%	$ 55,133	$ 49,594	$ 49,204
Dividend received deduction	(1,076)	(1,140)	(1,292)
Tax exempt interest	(2,155)	(2,065)	(1,977)
Tax adjustment on foreign currency	(358)	(214)	245
Adjustments pertaining to prior tax years	1	(273)	1,244
Nondeductible insurance	160	160	160
Nondeductible meals	277	121	112
Amortization of life interest in a trust	0	0	116
Other, net	(49)	(733)	211
Income Tax Expense (Benefit)	$ 51,933us-gaap_IncomeTaxExpenseBenefit	$ 45,450us-gaap_IncomeTaxExpenseBenefit	$ 48,023us-gaap_IncomeTaxExpenseBenefit
Statutory Rate	35.00%

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

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

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Amount 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 deduction for dividend.

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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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