XML 81 R53.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Commitments and Contingencies (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2011
Commitments and Contingencies [Abstract] |
Future Minimum Rental Commitments [Text Block] |
($ in millions) |  |
2012 | $ | 9.0
2013 |  | 6.0
2014 |  | 4.0
2015 |  | 2.6
2016 |  | 2.0
After 2016 |  | 1.8
Total minimum payment required | $ | 25.4

X
- Definition Tabular disclosure of the future minimum rental commitments for non-cancelable leases. + References No definition available. + Details
Name: | sigi_FutureMinimumRentalCommitmentsTextBlock
Namespace Prefix: | sigi_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_CommitmentsAndContingenciesDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration