XML 62 R49.htm IDEA: XBRL DOCUMENT v3.8.0.1

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Rental Commitments For Non-Cancelable Leases

($ in millions)		Capital Leases			Operating Leases		Total
2018		$	2.3		10.0		12.3
2019		0.1			7.5		7.6
2020		—			6.0		6.0
2021		—			3.7		3.7
2022		—			2.1		2.1
After 2022		—			2.6		2.6
Total minimum payment required		$	2.4		31.9		34.3

X

- Definition

Tabular disclosure of future minimum payments required in the aggregate and for each of the five succeeding fiscal years for capital and operating leases having initial or remaining non-cancelable lease terms in excess of one year and the total minimum rentals to be received in the future under non-cancelable subleases as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	sigi_ScheduleofFutureMinimumRentalCommitmentsForNonCancelableLeasesTableTextBlock
Namespace Prefix:	sigi_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- References

No definition available.

+ Details

Name:	us-gaap_CommitmentsAndContingenciesDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration