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Segment Information (Income From Continuing Operations, Before Federal Income Tax) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]
Net investment income	$ 35,534	$ 32,870
Net realized investment gains	7,218	3,355
Investment income, before federal income tax	42,752	36,225
Tax on investment income	11,575	9,205
Total investment income, after federal income tax	31,177	27,020
Total Standard Commercial Lines [Member]
Segment Reporting Information [Line Items]
Underwriting (loss) gain, before federal income tax	(3,630)	6,102
Total standard Personal Lines [Member]
Segment Reporting Information [Line Items]
Underwriting (loss) gain, before federal income tax	(2,360)	5,973
Total Standard Insurance Operations [Member]
Segment Reporting Information [Line Items]
Underwriting (loss) gain, before federal income tax	(5,990)	12,075
GAAP combined ratio	101.40%	96.90%
Statutory combined ratio	101.10%	96.80%
Excess And Surplus Operations [Member]
Segment Reporting Information [Line Items]
Underwriting (loss) gain, before federal income tax	$ 975	$ 86
GAAP combined ratio	97.00%	99.70%
Statutory combined ratio	97.90%	98.20%

X

- Definition

The income earned from investments in securities and other investments including dividends, interest, and returns on other investments. This item does not include realized gains (losses).

+ References

No definition available.

+ Details

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X

- Definition

The statutory combined ratio (expressed as a percentage) is the sum of: (i) the loss and loss expense ratio; (ii) the underwriting ratio; and (iii) the dividend ratio. The loss and loss expense ratio as well as the dividend ratio is calculated by dividing loss and loss expenses, as well as dividends to policyholders, by net premiums earned. The underwriting expense ratio is calculated by dividing underwriting expenses by net premiums written.

+ References

No definition available.

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X

- Definition

Taxes paid on investment income

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X

- Definition

Total investment income, after federal income tax

+ References

No definition available.

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X

- Definition

The income earned from investments in securities and other investments including dividends, interest, and returns on other investments, including realized gains/losses.

+ References

No definition available.

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X

- Definition

Net premiums earned and other insurance income less net loss and loss expenses incurred, loss adjustment expenses, policy acquisition costs and other underwriting expenses.

+ References

No definition available.

+ Details

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X

- Definition

Ratio of non-life losses and loss expenses, non-life acquisition expenses and non-life general and administrative expenses, to non-life net premiums earned.

+ References

No definition available.

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X

- Definition

The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.3(a))

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 325

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6485959&loc=d3e22529-158502



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 3

-Subparagraph a

-Article 7

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