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v2.3.0.11

Discontinued Operations (Narrative) (Details) (USD $) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2011 securities years | Jun. 30, 2010 | Jun. 30, 2011 securities years | Jun. 30, 2010 | Dec. 31, 2009
Discontinued Operations [Abstract] |  |  |  |  |
Percentage of interest sold in Selective HR |  |  |  |  | 100.00%
Period over which proceeds are scheduled to be received | 10 |  | 10 |  |
Estimated sales price of Selective HR | $ 6,900,000 |  | $ 6,900,000 |  |
Sales price received on subsidiary | 2,400,000 |  | 2,400,000 |  |
After-tax charge | $ 0 | $ (1,325,000) | $ 0 | $ (2,115,000) |

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- Definition This item represents the estimated proceeds associated with the sale of a subsidiary. + Details
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Namespace Prefix: | sigi
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition This item represents the percentage of the company's interest in its subsidiary that was sold. + Details
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Balance Type: | na
Period Type: | instant

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- Definition The number of years over which the proceeds from sale of subsidiary are scheduled to be received. + Details
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Balance Type: | na
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- Definition Amount of sales price for sale of subsidiary that has been received as of the balance sheet date. + Details
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Balance Type: | debit
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- Definition Gain (loss) after tax expense (benefit), not previously recognized and resulting from the sale of a business component, which is recognized at the date of sale. A gain (loss) reflects the amount by which the consideration received exceeds (is exceeded by) the net carrying amount (reflecting previous provisions for loss on disposal, if any) of the disposal group. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 43 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 47 -Subparagraph b + Details
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