XML 50 R38.htm IDEA: XBRL DOCUMENT v3.19.1

Investments (Other Investment Portfolio by Strategy and the Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy) (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Carrying Value		$ 176,225	$ 178,938
Other Investments [Member]
Carrying Value		176,225	178,938
Remaining Commitment		217,261	202,270
Maximum Exposure to Loss	[1]	393,486	381,208
Alternative Investments [Member]
Carrying Value		151,733	153,896
Remaining Commitment		217,261	202,270
Maximum Exposure to Loss	[1]	368,994	356,166
Private Equity [Member] | Alternative Investments [Member]
Carrying Value		92,371	84,352
Remaining Commitment		101,297	93,688
Maximum Exposure to Loss	[1]	193,668	178,040
Private Credit [Member] | Alternative Investments [Member]
Carrying Value		30,518	41,682
Remaining Commitment		90,812	81,453
Maximum Exposure to Loss	[1]	121,330	123,135
Real Assets [Member] | Alternative Investments [Member]
Carrying Value		28,844	27,862
Remaining Commitment		25,152	27,129
Maximum Exposure to Loss	[1]	53,996	54,991
Other Securities [Member]
Carrying Value		24,492	25,042
Remaining Commitment		0	0
Maximum Exposure to Loss	[1]	$ 24,492	$ 25,042
[1] The maximum exposure to loss includes both the carry value of these investments and the related unfunded commitments. In addition, tax credits that have been previously recognized in Other securities are subject to the risk of recapture, which we do not consider significant.

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

Amount of investments classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-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

+ Details

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

X

- Definition

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=108788376&loc=d3e5747-111685

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=108788376&loc=d3e5728-111685

+ Details

Name:	us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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=srt_PartnershipInterestMember
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_PrivateCreditFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSectorAxis=sigi_RealAssetsMember
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: