XML 158 R89.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Indebtedness (Narrative) (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Dec. 31, 2005 | Dec. 31, 2019 | Dec. 31, 2018 | Aug. 05, 2019 | Mar. 31, 2019 | Mar. 07, 2019 | Dec. 31, 2004
Maximum borrowing percentage |  | 10.00% |  |  |  |  |
Borrowing threshold of FHLBI |  | 20 |  |  |  |  |
Debt Issuance Costs, Gross |  |  |  |  | $ 3,300 |  |
Long-term debt |  | $ 550,597 | $ 439,540 |  |  |  |
Five Point Three Hundred Seventy Five [Member] |  |  |  |  |  |  |
Long-term Debt, Gross |  | $ 300,000 |  |  | $ 300,000 |  |
Interest Rate |  | 5.375% |  |  |  |  |
Discount for notes issued |  | $ 5,900 |  |  |  |  |
Net proceeds from the issuance |  | 290,800 |  |  |  |  |
Five Point Eight Hundred Seventy Five Percent Senior Notes [Member] |  |  |  |  |  |  |
Long-term Debt, Gross |  | $ 185,000 |  |  |  |  |
Interest Rate |  | 5.875% |  |  |  |  |
Debt Retirement Costs Before Tax |  | $ 4,200 |  |  |  |  |
Debt Retirement Costs Net of Tax |  | 3,300 |  |  |  |  |
Proceeds From Debt Issuance After Redemption |  | 106,000 |  |  |  |  |
Three Point Zero Three Percent Borrowing From Federal Home Loan Bank Due December 16, 2026 [Member] |  |  |  |  |  |  |
Long-term Debt, Gross |  | $ 60,000 |  |  |  |  |
Interest Rate |  | 3.03% |  |  |  |  |
Federal Home Loan Bank Advances |  |  | 45,000 |  |  |  |
Net proceeds from the issuance |  |  | 15,000 |  |  |  |
Six Point Seventy Percent Senior Notes due 2035 [Member] |  |  |  |  |  |  |
Long-term Debt, Gross |  | $ 100,000 |  |  |  |  |
Interest Rate |  | 6.70% |  |  |  |  |
Acceleration of principal |  | $ 10,000 |  |  |  |  |
Discount for notes issued | $ 700 |  |  |  |  |  |
Effective yield | 6.754% |  |  |  |  |  |
Net proceeds from the issuance | $ 50,000 |  |  |  |  |  |
Seven Point Twenty Five Percent Senior Notes due 2034 [Member] |  |  |  |  |  |  |
Long-term Debt, Gross |  | $ 50,000 |  |  |  |  |
Interest Rate |  | 7.25% |  |  |  |  |
Acceleration of principal |  | $ 10,000 |  |  |  |  |
Discount for notes issued |  |  |  |  |  |  | $ 100
Effective yield |  |  |  |  |  |  | 7.27%
Bond proceeds to Insurance Subsidiaries as capital |  |  |  |  |  |  | $ 25,000
Line of Credit expires Dec.20, 2022 [Member] |  |  |  |  |  |  |
Line of credit borrowing capacity |  | 50,000 | 30,000 |  |  |  |
Line of credit, maximum borrowing capacity |  | 125,000 | 50,000 |  |  |  |
Acceleration of principal |  | $ 20,000 |  |  |  |  |
Maximum borrowing percentage |  | 10.00% |  |  |  |  |
One Point Sixty One Percent Borrowing From Federal Home Loan Bank Due July 21, 2021 [Member] |  |  |  |  |  |  |
Long-term Debt, Gross |  | $ 25,000 |  |  |  |  |
Interest Rate |  | 1.61% |  |  |  |  |
One Point Fifty Six Percent Borrowing From Federal Home Loan Bank Due August 16, 2021 [Member] |  |  |  |  |  |  |
Long-term Debt, Gross |  | $ 25,000 |  |  |  |  |
Interest Rate |  | 1.56% |  |  |  |  |
Two Point Sixty Four Percent Borrowing From Federal Home Loan Bank Due March 28, 2019 [Member] |  |  |  |  |  |  |
Federal Home Loan Bank Advances |  |  |  |  |  | $ 50,000 |
Federal Home Loan Bank, Advances, Interest Rate |  |  |  |  |  | 2.64% |
Two Point Twenty Nine Percent Borrowing From Federal Home Loan Bank Due August 12, 2019 [Member] |  |  |  |  |  |  |
Federal Home Loan Bank Advances |  |  |  | $ 15,000 |  |  |
Federal Home Loan Bank, Advances, Interest Rate |  |  |  | 2.29% |  |  |
Federal Home Loan Bank of Indianapolis [Member] |  |  |  |  |  |  |
Aggregate investment in FHLBI |  | $ 2,800 |  |  |  |  |
Federal Home Loan Bank of New York [Member] |  |  |  |  |  |  |
Aggregate investment in FHLBI |  | $ 3,100 | $ 2,700 |  |  |  |

X
- Definition The cash inflow from the bond proceeds contributed to the Insurance Subsidiaries as capital. + References No definition available. + Details
Name: | sigi_BondProceeds
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount of debt discount that was originally recognized at the issuance of the instrument. + References No definition available. + Details
Name: | sigi_DebtInstrumentDiscount
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount, before tax, of debt retirement costs. + References No definition available. + Details
Name: | sigi_DebtRetirementCostsBeforeTax
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount, net of tax, of debt retirement costs. + References No definition available. + Details
Name: | sigi_DebtRetirementCostsNetofTax
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This amount is a multiple of the Company's aggregate investment in the Federal Home Loan Bank representing the Company's ability to borrow from the Federal Home Loan Bank. + References No definition available. + Details
Name: | sigi_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMultipleAmount
Namespace Prefix: | sigi_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The maximum collaterized borrowing percentage from SISE and SISC admitted assets + References No definition available. + Details
Name: | sigi_MaximumBorrowingPercentage
Namespace Prefix: | sigi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition This element represents the amount of concurrent debt outstanding which, if accelerated for any reason of default, causes an event of default on the referenced debt. + References No definition available. + Details
Name: | sigi_PrincipalAccelerationAmountStateofDefault
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Remaining proceeds from the issuance of debt, net of issuance costs and after the redemption of previous debt outstanding. + References No definition available. + Details
Name: | sigi_ProceedsFromDebtIssuanceAfterRedemption
Namespace Prefix: | sigi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870 Reference 2: 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(16)) -URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910 Reference 3: 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(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6036836-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399 + Details
Name: | us-gaap_DeferredFinanceCostsGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of Federal Home Loan Bank (FHLBank) advances to member financial institutions. + References No definition available. + Details
Name: | us-gaap_FederalHomeLoanBankAdvances
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Interest rate of advances made and reported by Federal Home Loan Bank (FHLBank). + References No definition available. + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 325 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=75031641&loc=d3e63345-112809 + Details
Name: | us-gaap_FederalHomeLoanBankStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870 Reference 2: 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(a)(16)) -URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: 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(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebtPercentageBearingFixedInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromDebtNetOfIssuanceCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=sigi_FivePointThreeHundredSeventyFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=sigi_FivePointEightHundredSeventyFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=sigi_ThreePointZeroThreePercentBorrowingFromFederalHomeLoanBankDueDecember162026Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=sigi_SixPointSeventyPercentSeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=sigi_SevenPointTwentyFivePercentSeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=sigi_OnePointSixtyOnePercentBorrowingFromFederalHomeLoanBankDueJuly212021Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=sigi_OnePointFiftySixPercentBorrowingFromFederalHomeLoanBankDueAugust162021Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortTermDebtTypeAxis=sigi_OnePointSeventyFivePercentBorrowingFromFederalHomeLoanBankDueMarch202018Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortTermDebtTypeAxis=sigi_OnePointNinetyEightPercentBorrowingFromFederalHomeLoanBankDueApril182018Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_FederalHomeLoanBankAdvancesBranchOfFHLBBankAxis=srt_FederalHomeLoanBankOfIndianapolisMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_FederalHomeLoanBankAdvancesBranchOfFHLBBankAxis=srt_FederalHomeLoanBankOfNewYorkMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |