Represents the committed amount of investment in limited partnership made by the company.

No definition available.

Name:	saft_InvestmentInLimitedPartnershipCommittedAmount
Namespace Prefix:	saft_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The length of the lease extension under the amended lease agreement.

+ References

No definition available.

+ Details

Name:	saft_LesseeLeasingArrangementsOperatingLeasesAdditionalTermOfContract
Namespace Prefix:	saft_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of renewal terms under operating leases.

+ References

No definition available.

+ Details

Name:	saft_LesseeLeasingArrangementsOperatingLeasesNumberOfRenewalTerms
Namespace Prefix:	saft_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of contribution made by the company to the limited partnership investment.

+ References

No definition available.

+ Details

Name:	saft_LimitedPartnershipInvestmentMade
Namespace Prefix:	saft_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the amount of remaining committed capital due to be called.

+ References

No definition available.

+ Details

Name:	saft_LimitedPartnershipInvestmentToBeMade
Namespace Prefix:	saft_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the amount of the provision reserved for collectability of the reinsurance recoverables in arbitration.

+ References

No definition available.

+ Details

Name:	saft_ReinsuranceRecoverableArbitrationAllowanceForCollectability
Namespace Prefix:	saft_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of reinsurance recoverable in arbitration including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

+ References

No definition available.

+ Details

Name:	saft_ReinsuranceRecoverableInArbitration
Namespace Prefix:	saft_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Term of the lessee's leasing arrangement renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_LesseeLeasingArrangementsOperatingLeasesRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 3)
-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41502-112717

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

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

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41502-112717

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 3)
-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697

+ Details

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

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

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

- Definition

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717

+ Details

Name:	us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_TypeOfArrangementAxis=us-gaap_LeaseAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies (Details) $ in Thousands		12 Months Ended
Commitments and Contingencies (Details) $ in Thousands	Apr. 05, 2007 item	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 15, 2015 USD ($)
Lease of office space
Rental Expense		$ 4,242	$ 4,293	$ 4,236
Minimum annual rental payments due
2017		3,990
2018		3,963
2019		192
Total minimum lease payments		8,145
Investment in limited partnership, committed amount		40,000
Contribution made		19,757
Contributions to be made		$ 20,243
Reinsurance recoverables in arbitration					$ 22,838
Provision for collectability of the reinsurance recoverables in arbitration			$ 0
Eight Amendment to lease agreement
Minimum annual rental payments due
Lease extension, additional term commencing on January 1, 2009	10 years
Number of renewal terms \| item	1
Renewal term	5 years