XML 41 R53.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Segment Information (Revenue From Continuing Operations by Segment) (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended
--- | ---
Mar. 31, 2013 | Mar. 31, 2012
Segment Reporting Information [Line Items] |  |
Total net premiums earned | $ 420,940 | $ 378,829
Other income | 2,784 | 3,533
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 | 459,885 | 419,272
Total revenues | 459,949 | 419,348
Commercial Automobile [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 74,347 | 70,484
Workers Compensation [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 66,084 | 65,811
General Liability [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 97,703 | 90,143
Commercial Property [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 53,415 | 49,371
Business Owners' Policies [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 18,540 | 16,857
Bonds Segment [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 4,764 | 4,663
Other Commercial [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 2,992 | 3,168
Total standard Commercial Lines [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 317,845 | 300,497
Personal Automobile [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 38,393 | 37,456
Homeowners [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 31,135 | 27,958
Other Personal [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 3,508 | 3,195
Total standard Personal Lines [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 73,036 | 68,609
Total Standard Insurance Operations [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 390,881 | 369,106
Total insurance operations revenues | 393,601 | 372,563
Miscellaneous Income [Member] |  |
Segment Reporting Information [Line Items] |  |
Other income | 2,720 | 3,457
Excess And Surplus Operations [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 30,059 | 9,723
Other Income [Member] |  |
Segment Reporting Information [Line Items] |  |
Other income | $ 64 | $ 76

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 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 Revenue from insurance services, including net premiums earned, gain on sale of insurance block, agency management fees and insurance contract fees and commissions. + 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 210.7-04.1,4) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 + Details
Name: | us-gaap_InsuranceServicesRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Reflects the sum of all other revenue and income recognized by the entity in the period not otherwise specified in the income statement. + 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 210.7-04.4) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 4 -Article 7 + Details
Name: | us-gaap_OtherIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Premiums recognized as revenue in the period earned on all property and casualty insurance and reinsurance contracts after subtracting any amounts ceded to another insurer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 18 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (b),(c) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 113 -Paragraph 27 -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. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.1) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 1 -Article 7 + Details
Name: | us-gaap_PremiumsEarnedNetPropertyAndCasualty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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
- Definition Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains. + 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 210.5-03.1) -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 1 -Article 5 + Details
Name: | us-gaap_Revenues
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

X
- Definition Amount of total revenue for the reportable segments, including revenue from external customers, transactions with other operating segments of the same entity, and (gross) interest revenue. All considered to be "operating revenue" for purposes of the taxonomy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (a),(b),(c) -URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8736-108599 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 131 -Paragraph 27 -Subparagraph a, b, c -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_SegmentReportingInformationRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration