XML 63 R34.htm IDEA: XBRL DOCUMENT v3.2.0.727

Investments (Other Investment Portfolio by Strategy and the Remaining Commitment Amount Associated With Each Strategy) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Carrying Value	$ 85,420	$ 99,203
Other Investments [Member]
Carrying Value	85,420	99,203
Remaining Commitment	64,530
Alternative Investments [Member]
Carrying Value	74,188	92,968
Remaining Commitment	62,261
Secondary Private Equity Member | Alternative Investments [Member]
Carrying Value	18,997	21,807
Remaining Commitment	7,072
Private Equity [Member] | Alternative Investments [Member]
Carrying Value	16,027	20,126
Remaining Commitment	8,823
Energy Power Generation [Member] | Alternative Investments [Member]
Carrying Value	9,662	14,445
Remaining Commitment	19,610
Real Estate Strategy [Member] | Alternative Investments [Member]
Carrying Value	8,242	11,452
Remaining Commitment	9,975
Mezzanine Financing [Member] | Alternative Investments [Member]
Carrying Value	7,563	9,853
Remaining Commitment	13,383
Distressed debt [Member] | Alternative Investments [Member]
Carrying Value	7,000	8,679
Remaining Commitment	3,048
Venture Capital [Member] | Alternative Investments [Member]
Carrying Value	6,697	6,606
Remaining Commitment	350
Other Securities [Member]
Carrying Value	11,232	$ 6,235
Remaining Commitment	$ 2,269

X

- Definition

This item represents contractual obligations to invest additional amounts on our other investment portfolio. These additional investments may or may not be required.

+ References

No definition available.

+ Details

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

X

- Definition

Other investments not otherwise specified in the taxonomy.

+ References

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



-Publisher FASB



-Name Accounting Standards Codification



-Topic 210



-SubTopic 10



-Section S99



-Paragraph 1



-Subparagraph (SX 210.5-02.12)



-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



Reference 2: 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(f,g))



-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_OtherInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_OtherInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_PartnershipInterestMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSectorAxis=sigi_SecondaryPrivateEquityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSectorAxis=us-gaap_PrivateEquityFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSectorAxis=sigi_EnergyPowerGenerationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSectorAxis=sigi_RealEstateStrategyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSectorAxis=sigi_MezzanineFinancingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSectorAxis=sigi_DistressedDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSectorAxis=us-gaap_VentureCapitalFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSectorAxis=sigi_OtherSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: