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Federal Income Taxes (Reconciliation of Federal Income Tax on Income at the Corporate Rate to the Effective Tax Rate) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Tax at statutory rate of 35%	$ 76,984	$ 81,442	$ 68,996
Tax-advantaged interest	(12,126)	(13,164)	(12,926)
Dividends received deduction	(1,114)	(1,817)	(1,121)
Other	(2,284)	370	355
Total federal income tax expense	$ 61,460	$ 66,831	$ 55,304

X

- Definition

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 investment income that is tax advantaged. Tax advantaged investment securities generally are, by statute, tax-reduced, tax-deferred, or tax-free.

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
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-Topic 235
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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