XML 14 R54.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Segment Information (Income From Continuing Operations, Before Federal Income Tax) (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended
--- | ---
Mar. 31, 2013 | Mar. 31, 2012
Segment Reporting Information [Line Items] |  |
Net investment income | $ 32,870 | $ 32,628
Net realized investment gains | 3,355 | 4,358
Total investment revenues | 36,225 | 36,986
Total all segments | 48,386 | 35,623
Interest expense | (5,831) | (4,700)
General corporate and other expenses | (13,687) | (7,732)
Income from continuing operations before federal income tax | 28,868 | 23,191
Total standard Commercial Lines [Member] |  |
Segment Reporting Information [Line Items] |  |
Underwriting gain (loss), before federal income tax | 6,102 | 409
Total standard Personal Lines [Member] |  |
Segment Reporting Information [Line Items] |  |
Underwriting gain (loss), before federal income tax | 5,973 | 3,121
Total Standard Insurance Operations [Member] |  |
Segment Reporting Information [Line Items] |  |
Underwriting gain (loss), before federal income tax | 12,075 | 3,530
GAAP combined ratio | 96.90% | 99.00%
Statutory combined ratio | 96.80% | 98.00%
Excess And Surplus Operations [Member] |  |
Segment Reporting Information [Line Items] |  |
Underwriting gain (loss), before federal income tax | $ 86 | $ (4,893)
GAAP combined ratio | 99.70% | 150.30%
Statutory combined ratio | 98.20% | 120.30%

X
- Definition The GAAP combined ratio (expressed as a percentage) is a calculation wherein the sum of: (i) loss and loss adjustment expenses (ii) underwriting expenses and (iii) dividends to policyholders is divided by net premiums earned. + References No definition available. + Details
Name: | sigi_GaapCombinedRatio
Namespace Prefix: | sigi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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
Name: | sigi_NetInvestmentIncomeEarned
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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. + Details
Name: | sigi_StatutoryCombinedRatio
Namespace Prefix: | sigi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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. + Details
Name: | sigi_TotalInvestmentRevenues
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Total of all reportable segments' income or loss from continuing operations, before federal income taxes. + References No definition available. + Details
Name: | sigi_TotalSegmentIncomeLossFromContinuingOperationsBeforeFederalIncomeTax
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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
Name: | sigi_UnderwritingIncomeLossBeforeFederalIncomeTaxes
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, and noncontrolling interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 10 -Article 5 + Details
Name: | us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 8 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 34 -Paragraph 21 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_InterestExpenseDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of general expenses not normally included in Other Operating Costs and Expenses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.6) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 6 -Article 5 + Details
Name: | us-gaap_OtherGeneralExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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 + Details
Name: | us-gaap_RealizedInvestmentGainsLosses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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