XML 129 R116.htm IDEA: XBRL DOCUMENT v3.8.0.1

Statutory Financial Information, Capital Requirements and Restrictions on Dividends and Transfers of Funds (Statutory Financial Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statutory unassigned surplus	$ 1,137.3	$ 1,048.2
Statutory surplus	1,672.9	1,583.8
Statutory net income	221.2	202.3	$ 195.8
Selective Insurace Company of America (SICA) [Member]
Statutory unassigned surplus	455.5	414.4
Statutory surplus	609.7	568.6
Statutory net income	84.6	72.2	69.6
Selective Way Insurance Company (SWIC) [Member]
Statutory unassigned surplus	276.1	260.5
Statutory surplus	325.1	309.5
Statutory net income	43.6	41.2	42.3
Selective Insurance Company of South Carolina (SICSC) [Member]
Statutory unassigned surplus	112.9	110.6
Statutory surplus	144.1	141.9
Statutory net income	17.9	17.4	15.9
Selective Insurance Company of the Southeast (SICSE) [Member]
Statutory unassigned surplus	86.2	83.5
Statutory surplus	111.8	109.1
Statutory net income	14.7	13.4	12.1
Selective Insurance Company of New York (SICNY) [Member]
Statutory unassigned surplus	78.8	74.1
Statutory surplus	106.5	101.8
Statutory net income	13.4	12.9	12.7
Selective Insurance Company of New England (SICNE) [Member]
Statutory unassigned surplus	16.1	13.6
Statutory surplus	46.3	43.7
Statutory net income	6.3	5.9	5.5
Selective Auto Insurance Company of New Jersey (SAICNJ) [Member]
Statutory unassigned surplus	42.1	36.9
Statutory surplus	84.9	79.8
Statutory net income	11.4	11.5	10.8
Mesa Underwriting Specialty Insurance Company (MUSIC) [Member]
Statutory unassigned surplus	21.4	16.7
Statutory surplus	89.9	85.2
Statutory net income	10.3	9.7	9.5
Selective Casualty Insurance Company (SCIC) [Member]
Statutory unassigned surplus	34.5	26.6
Statutory surplus	109.0	101.0
Statutory net income	13.4	12.6	12.1
Selective Fire and Casualty Insurance Company (SFCIC) [Member]
Statutory unassigned surplus	13.7	11.3
Statutory surplus	45.6	43.2
Statutory net income	$ 5.6	$ 5.5	$ 5.3

X

- Definition

The amount of statutory unassigned surplus as of the balance sheet date using prescribed or permitted statutory accounting practices (rather than GAAP, if different) of the state or country.

+ References

No definition available.

+ Details

Name:	sigi_StatutoryAccountingPracticesStatutoryUnassignedSurplus
Namespace Prefix:	sigi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

The amount of statutory capital and surplus (stockholders' equity) as of the balance sheet date using prescribed or permitted statutory accounting practices (rather than GAAP, if different) of the state or country.

+ References

Reference 1: 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(a)(23)(c))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6486098&loc=d3e24708-158529

+ Details

Name:	us-gaap_StatutoryAccountingPracticesStatutoryCapitalAndSurplusBalance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount of net income for the period determined using accounting principles prescribed or permitted by insurance regulators.

+ References

Reference 1: 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(a)(23)(c))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_StatutoryAccountingPracticesStatutoryNetIncomeAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

Name:	sigi_StatutoryDataAxis=sigi_SelectiveInsuranceCompanyOfAmericaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	sigi_StatutoryDataAxis=sigi_SelectiveWayInsuranceCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	sigi_StatutoryDataAxis=sigi_SelectiveInsuranceCompanyOfSouthCarolinaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	sigi_StatutoryDataAxis=sigi_SelectiveInsuranceCompanyOfSoutheastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	sigi_StatutoryDataAxis=sigi_SelectiveInsuranceCompanyOfNewYorkMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	sigi_StatutoryDataAxis=sigi_SelectiveInsuranceCompanyOfNewEnglandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	sigi_StatutoryDataAxis=sigi_SelectiveAutoInsuranceCompanyOfNewJerseyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	sigi_StatutoryDataAxis=sigi_MesaUnderwritingSpecialtyInsuranceCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	sigi_StatutoryDataAxis=sigi_SelectiveCasualtyInsuranceCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	sigi_StatutoryDataAxis=sigi_SelectiveFireAndCasualtyInsuranceCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: