XML 61 R65.htm IDEA: XBRL DOCUMENT v2.4.0.8

Discontinued Operations (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Sep. 30, 2013	Dec. 31, 2009
Percentage Of Interest Sold In Subsidiary			100.00%
Receivable amount related to sale of subsidiary		$ 1.0
Discontinued gain (loss) from disposal of discontinued operation, before federal income tax	$ (1.5)

X

- Definition

This item represents the percentage of the company's interest in its subsidiary that was sold.

+ References

No definition available.

+ Details

Name:	sigi_PercentageOfInterestSoldInSubsidiary
Namespace Prefix:	sigi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Receivble amount related to sale of subsidiary

+ References

No definition available.

+ Details

Name:	sigi_ReceivableRelatedToSaleOfSubsidiary
Namespace Prefix:	sigi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of gain (loss), before tax expense or benefit and not previously recognized, resulting from the sale of a business component.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e957-107759



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration