XML 126 R33.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Investments (Held-To-Maturity Securities Disclosure) (Details) (USD $) | 6 Months Ended |
--- | --- | ---
Jun. 30, 2013 Securities | Dec. 31, 2012
Schedule of Held-to-maturity Securities [Line Items] |  |
Amortized Cost | $ 476,894,000 | $ 550,143,000
Net Unrealized Gains (Losses) | 2,613,000 | 3,926,000
Carrying Value | 479,507,000 | 554,069,000
Unrecognized Holding Gains | 28,152,000 | 40,615,000
Unrecognized Holding Losses | (34,000) | (23,000)
Fixed maturity securities, held-to-maturity, fair value | 507,625,000 | 594,661,000
Held To Maturity securities average duration | 2 years 3 months 18 days |
Number of held to maturity securities transferred to available-for-sale | 10 |
Securities reclassified from the HTM category to AFS carrying value | 22,900,000 |
Securities reclassified from the HTM category to AFS net unrecognized gain | 1,100,000 |
Foreign Government [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Amortized Cost | 5,292,000 | 5,292,000
Net Unrealized Gains (Losses) | 172,000 | 212,000
Carrying Value | 5,464,000 | 5,504,000
Unrecognized Holding Gains | 194,000 | 367,000
Unrecognized Holding Losses | 0 | 0
Fixed maturity securities, held-to-maturity, fair value | 5,658,000 | 5,871,000
Obligations of States and Political Subdivisions [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Amortized Cost | 421,460,000 | 491,180,000
Net Unrealized Gains (Losses) | 4,947,000 | 6,769,000
Carrying Value | 426,407,000 | 497,949,000
Unrecognized Holding Gains | 20,520,000 | 28,996,000
Unrecognized Holding Losses | (34,000) | (23,000)
Fixed maturity securities, held-to-maturity, fair value | 446,893,000 | 526,922,000
Corporate Securities [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Amortized Cost | 35,983,000 | 38,285,000
Net Unrealized Gains (Losses) | (643,000) | (812,000)
Carrying Value | 35,340,000 | 37,473,000
Unrecognized Holding Gains | 3,541,000 | 4,648,000
Unrecognized Holding Losses | 0 | 0
Fixed maturity securities, held-to-maturity, fair value | 38,881,000 | 42,121,000
Asset-backed Securities [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Amortized Cost | 6,536,000 | 6,980,000
Net Unrealized Gains (Losses) | (824,000) | (1,052,000)
Carrying Value | 5,712,000 | 5,928,000
Unrecognized Holding Gains | 868,000 | 1,170,000
Unrecognized Holding Losses | 0 | 0
Fixed maturity securities, held-to-maturity, fair value | 6,580,000 | 7,098,000
Commercial Mortgage-backed Securities ("CMBS") [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Amortized Cost | 7,623,000 | 8,406,000
Net Unrealized Gains (Losses) | (1,039,000) | (1,191,000)
Carrying Value | 6,584,000 | 7,215,000
Unrecognized Holding Gains | 3,029,000 | 5,434,000
Unrecognized Holding Losses | 0 | 0
Fixed maturity securities, held-to-maturity, fair value | $ 9,613,000 | $ 12,649,000

X
- Definition This item represents debt securities categorized as held-to-maturity, at cost, net of adjustments made for amortization and net unrealized gains (losses) resulting from: (i) other-than-temporary impairments and (ii) a previous available-for-sale designation. + References No definition available. + Details
Name: | sigi_HeldToMaturitySecuritiesAmortizedCost
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Held to maturity securities average duration. + References No definition available. + Details
Name: | sigi_HeldToMaturitySecuritiesAverageDuration
Namespace Prefix: | sigi_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition As of the balance sheet date, the excess of fair value over carrying value of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding gain. + References No definition available. + Details
Name: | sigi_HeldToMaturitySecuritiesGrossUnrecognizedHoldingGains
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition As of the balance sheet date, the excess of carrying value over fair value of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding loss. + References No definition available. + Details
Name: | sigi_HeldToMaturitySecuritiesGrossUnrecognizedHoldingLosses
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The remaining aggregate increase (decrease) in the market value of held-to-maturity securities either (i) prior to the securities' transfer to a held-to-maturity designation or (ii) resulting from a non-credit other-than-temporary impairment. + References No definition available. + Details
Name: | sigi_HeldToMaturitySecuritiesNetUnrealizedGainsLosses
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the number of held-to-maturity securities reclassified to available-for-sale securities due to an unanticipated significant deterioration in credit quality. + References No definition available. + Details
Name: | sigi_NumberOfHeldToMaturitySecuritiesTransferredSecurityAtCarryingValue
Namespace Prefix: | sigi_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity. The held-to-maturity category is for those securities that the entity has the positive intent and ability to hold until maturity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 10 -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 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 43 -Section A -Paragraph 5 -Chapter 3 -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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 11 -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 Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 19 -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 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 17 -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 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7534914&loc=d3e22054-111558 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 7 -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 8: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 43 -Section A -Paragraph 4 -Chapter 3 -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 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.6) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 10: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 11: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 8 -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 12: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 9 -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_HeldToMaturitySecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the aggregate fair value of investments in debt securities as of the balance sheet date and which are categorized as held-to-maturity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 19 -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 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 137 -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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27232-111563 + Details
Name: | us-gaap_HeldToMaturitySecuritiesFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition For any transfer of securities categorized as held-to-maturity, this item represents the net carrying amount of the transferred security to another category of investments in debt and equity securities (trading or available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 22 -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 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27405-111563 + Details
Name: | us-gaap_HeldToMaturitySecuritiesTransferredSecurityAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the unrealized gain (loss) recognized in other comprehensive income (a separate component of shareholders' equity) as a result of securities categorized as held-to-maturity being transferred to the available-for-sale securities category. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27405-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13, 22 -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_HeldToMaturitySecuritiesTransferredToAvailableForSaleSecuritiesUnrealizedGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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