$SIGI
Selective Insurance Group Inc Stock $sigi

$sigi Overview Financials Valuation SEC Filings Company Website

2020 Q3 Form 10-Q Financial Statement

#000023055720000018 Filed on July 31, 2020

Income Statement

Concept	2020 Q3	2020 Q2	2019 Q2
Revenue	$776.6M	$682.4M	$708.2M
YoY Change	9.31%	-3.64%	8.63%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin	$3.900M	$6.300M	$12.10M
YoY Change	-54.65%	-47.93%	266.67%
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$142.3M	$136.9M	$133.4M
YoY Change	4.19%	2.65%	8.76%
% of Gross Profit
Operating Expenses	$683.5M	$631.8M	$610.6M
YoY Change	8.18%	3.47%	6.51%
Operating Profit
YoY Change
Interest Expense	-$7.800M	-$7.900M	-$7.400M
YoY Change	5.41%	6.76%	21.31%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$85.26M	$42.69M	$90.23M
YoY Change	19.78%	-52.68%	24.41%
Income Tax	$15.38M	$8.510M	$17.96M
% Of Pretax Income	18.04%	19.93%	19.9%
Net Earnings	$69.88M	$34.18M	$72.27M
YoY Change	24.44%	-52.7%	22.86%
Net Earnings / Revenue	9.0%	5.01%	10.2%
Basic Earnings Per Share	$1.17	$0.57	$1.22
Diluted Earnings Per Share	$1.16	$0.57	$1.21
COMMON SHARES
Basic Shares Outstanding	59.81M shares	59.71M shares	59.23M shares
Diluted Shares Outstanding

Balance Sheet

Concept	2020 Q3	2020 Q2	2019 Q2
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$15.90M	$5.637M	$7.643M
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment	$78.44M	$78.77M	$73.68M
YoY Change	2.64%	6.91%	17.45%
Goodwill	$7.849M	$7.849M	$7.849M
YoY Change	0.0%	0.0%	0.0%
Intangibles
YoY Change
Long-Term Investments	$7.278B	$7.130B	$6.421B
YoY Change	11.08%	11.04%	13.34%
Other Assets	$15.10M	$5.000M	$21.80M
YoY Change	-0.66%	-77.06%	-65.51%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$9.515B	$9.306B	$8.576B
YoY Change	9.12%	8.52%	11.29%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$93.10M	$82.70M	$117.9M
YoY Change	-28.22%	-29.86%	38.06%
Deferred Revenue
YoY Change
Short-Term Debt	$167.0M	$252.0M	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$260.1M	$345.3M	$121.1M
YoY Change	96.45%	185.14%	33.81%
LONG-TERM LIABILITIES
Long-Term Debt	$550.6M	$550.6M	$550.8M
YoY Change	-0.02%	-0.04%	25.38%
Other Long-Term Liabilities	$346.4M	$305.6M	$280.2M
YoY Change	26.79%	9.06%	18.48%
Total Long-Term Liabilities	$897.0M	$856.2M	$831.0M
YoY Change	8.87%	3.03%	22.97%
TOTAL LIABILITIES
Total Short-Term Liabilities	$260.1M	$345.3M	$121.1M
Total Long-Term Liabilities	$897.0M	$856.2M	$831.0M
Total Liabilities	$7.121B	$7.007B	$6.516B
YoY Change	8.19%	7.54%	8.47%
SHAREHOLDERS EQUITY
Retained Earnings	$2.160B	$2.104B	$1.968B
YoY Change	7.31%	6.87%	10.59%
Common Stock	$646.8M	$642.9M	$614.0M
YoY Change	4.46%	4.7%	4.59%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$599.9M	$599.8M	$591.4M
YoY Change	1.2%	1.43%	1.2%
Treasury Stock Shares	44.13M shares	44.13M shares	44.00M shares
Shareholders Equity	$2.394B	$2.299B	$2.060B
YoY Change
Total Liabilities & Shareholders Equity	$9.515B	$9.306B	$8.576B
YoY Change	9.12%	8.52%	11.29%

Cashflow Statement

Concept	2020 Q3	2020 Q2	2019 Q2
OPERATING ACTIVITIES
Net Income	$69.88M	$34.18M	$72.27M
YoY Change	24.44%	-52.7%	22.86%
Depreciation, Depletion And Amortization	$142.3M	$136.9M	$133.4M
YoY Change	4.19%	2.65%	8.76%
Cash From Operating Activities	$183.5M	$158.1M	$118.5M
YoY Change	21.44%	33.42%	18.5%
INVESTING ACTIVITIES
Capital Expenditures	-$5.300M	-$4.200M	-$9.000M
YoY Change	-28.38%	-53.33%	95.65%
Acquisitions
YoY Change
Other Investing Activities	-$70.20M	-$102.5M	-$103.2M
YoY Change	-45.41%	-0.68%	218.52%
Cash From Investing Activities	-$75.50M	-$106.7M	-$112.3M
YoY Change	-44.49%	-4.99%	204.34%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-97.80M	-60.30M	-9.100M
YoY Change	676.19%	562.64%	-85.67%
NET CHANGE
Cash From Operating Activities	183.5M	158.1M	118.5M
Cash From Investing Activities	-75.50M	-106.7M	-112.3M
Cash From Financing Activities	-97.80M	-60.30M	-9.100M
Net Change In Cash	10.20M	-8.900M	-2.900M
YoY Change	308.0%	206.9%	625.0%
FREE CASH FLOW
Cash From Operating Activities	$183.5M	$158.1M	$118.5M
Capital Expenditures	-$5.300M	-$4.200M	-$9.000M
Free Cash Flow	$188.8M	$162.3M	$127.5M
YoY Change	19.12%	27.29%	21.89%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
	dei	Entity Small Business EntitySmallBusiness	false
CY2019Q4	sigi	Commercialmortgageloanfairvalue Commercialmortgageloanfairvalue	0	USD
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	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
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	dei	Document Type DocumentType	10-Q
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Document Period End Date DocumentPeriodEndDate	2020-06-30
	dei	Document Transition Report DocumentTransitionReport	false
	dei	Entity File Number EntityFileNumber	001-33067
	dei	Entity Registrant Name EntityRegistrantName	SELECTIVE INSURANCE GROUP, INC
	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	NJ
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	22-2168890
	dei	Entity Address Address Line1 EntityAddressAddressLine1	40 Wantage Avenue
	dei	Entity Address City Or Town EntityAddressCityOrTown	Branchville
	dei	Entity Address State Or Province EntityAddressStateOrProvince	NJ
	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	07890
	dei	City Area Code CityAreaCode	973
	dei	Local Phone Number LocalPhoneNumber	948-3000
	dei	Security12b Title Security12bTitle	Common Stock, par value $2 per share
	dei	Trading Symbol TradingSymbol	SIGI
	dei	Security Exchange Name SecurityExchangeName	NASDAQ
	dei	Amendment Flag AmendmentFlag	false
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q2
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2020
	dei	Entity Central Index Key EntityCentralIndexKey	0000230557
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
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CY2019Q2	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	133401000	USD
	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	273432000	USD
	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	263075000	USD
CY2020Q2	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	84601000	USD
CY2019Q2	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	86662000	USD
	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	179947000	USD
	us-gaap	Other Underwriting Expense OtherUnderwritingExpense	171741000	USD
CY2020Q2	us-gaap	Interest Expense Debt InterestExpenseDebt	7928000	USD
CY2019Q2	us-gaap	Interest Expense Debt InterestExpenseDebt	7366000	USD
	us-gaap	Interest Expense Debt InterestExpenseDebt	15529000	USD
	us-gaap	Interest Expense Debt InterestExpenseDebt	18892000	USD
CY2020Q2	us-gaap	Operating Costs And Expenses OperatingCostsAndExpenses	6345000	USD
CY2019Q2	us-gaap	Operating Costs And Expenses OperatingCostsAndExpenses	9566000	USD
	us-gaap	Operating Costs And Expenses OperatingCostsAndExpenses	15405000	USD
	us-gaap	Operating Costs And Expenses OperatingCostsAndExpenses	21976000	USD
CY2020Q2	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	639754000	USD
CY2019Q2	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	617979000	USD
	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	1288586000	USD
	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	1243247000	USD
CY2020Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	42693000	USD
CY2019Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	90225000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	58690000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	163919000	USD
CY2020Q2	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-1350000	USD
CY2019Q2	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	17958000	USD
	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	8536000	USD
	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	30539000	USD
CY2020Q2	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	9860000	USD
CY2019Q2	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	1000	USD
	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	735000	USD
	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-234000	USD
CY2020Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	8510000	USD
CY2019Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	17959000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	9271000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	30305000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	34183000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	72266000	USD
	us-gaap	Net Income Loss NetIncomeLoss	49419000	USD
	us-gaap	Net Income Loss NetIncomeLoss	133614000	USD
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.57
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.22
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.25
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.57
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.21
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.82
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.23
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	34183000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	72266000	USD
	us-gaap	Net Income Loss NetIncomeLoss	49419000	USD
	us-gaap	Net Income Loss NetIncomeLoss	133614000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	149127000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	66002000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	74882000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	147315000	USD
CY2020Q2	sigi	Non Credit Portionof Other Than Temporary Impairments Recognizedin Other Comprehensive Income NonCreditPortionofOtherThanTemporaryImpairmentsRecognizedinOtherComprehensiveIncome	29608000	USD
CY2019Q2	sigi	Non Credit Portionof Other Than Temporary Impairments Recognizedin Other Comprehensive Income NonCreditPortionofOtherThanTemporaryImpairmentsRecognizedinOtherComprehensiveIncome	0	USD
	sigi	Non Credit Portionof Other Than Temporary Impairments Recognizedin Other Comprehensive Income NonCreditPortionofOtherThanTemporaryImpairmentsRecognizedinOtherComprehensiveIncome	-22050000	USD
	sigi	Non Credit Portionof Other Than Temporary Impairments Recognizedin Other Comprehensive Income NonCreditPortionofOtherThanTemporaryImpairmentsRecognizedinOtherComprehensiveIncome	0	USD
CY2020Q2	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	25000	USD
CY2019Q2	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	17000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	5000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	24000	USD
CY2020Q2	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securities Netof Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesNetofTax	-1332000	USD
CY2019Q2	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securities Netof Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesNetofTax	-1027000	USD
	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securities Netof Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesNetofTax	7616000	USD
	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securities Netof Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesNetofTax	-1878000	USD
CY2020Q2	sigi	Debt Securities Availableforsale Allowancefor Credit Loss Net DebtSecuritiesAvailableforsaleAllowanceforCreditLossNet	-3890000	USD
CY2019Q2	sigi	Debt Securities Availableforsale Allowancefor Credit Loss Net DebtSecuritiesAvailableforsaleAllowanceforCreditLossNet	0	USD
	sigi	Debt Securities Availableforsale Allowancefor Credit Loss Net DebtSecuritiesAvailableforsaleAllowanceforCreditLossNet	8582000	USD
	sigi	Debt Securities Availableforsale Allowancefor Credit Loss Net DebtSecuritiesAvailableforsaleAllowanceforCreditLossNet	0	USD
CY2020Q2	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	-173488000	USD
CY2019Q2	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	-64958000	USD
	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	-69025000	USD
	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	-145413000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-595000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-524000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-1191000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-1049000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-595000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-524000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1191000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1049000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	174083000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	65482000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	70216000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	146462000	USD
CY2020Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	208266000	USD
CY2019Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	137748000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	119635000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	280076000	USD
CY2020Q2	us-gaap	Stockholders Equity StockholdersEquity	2298675000	USD
CY2019Q2	us-gaap	Stockholders Equity StockholdersEquity	2059544000	USD
CY2020Q2	us-gaap	Stockholders Equity StockholdersEquity	2298675000	USD
CY2019Q2	us-gaap	Stockholders Equity StockholdersEquity	2059544000	USD
CY2020Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.23
CY2019Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.20
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.46
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.40
CY2020Q1	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	59707545	shares
CY2019Q1	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	59222905	shares
CY2019Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	59461153	shares
CY2018Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	58948554	shares
CY2020Q2	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	7899	shares
CY2019Q2	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	5218	shares
	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	14874	shares
	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	10912	shares
CY2020Q2	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	97365	shares
CY2019Q2	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	101650	shares
	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	438601	shares
	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	473278	shares
CY2020Q2	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	1067	shares
CY2019Q2	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	1665	shares
	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	102886	shares
	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	104636	shares
CY2020Q2	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	59811742	shares
CY2019Q2	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	59328108	shares
CY2020Q2	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	59811742	shares
CY2019Q2	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	59328108	shares
	us-gaap	Net Income Loss NetIncomeLoss	49419000	USD
	us-gaap	Net Income Loss NetIncomeLoss	133614000	USD
	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	29634000	USD
	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	28327000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	11198000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	11654000	USD
	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	-7319000	USD
	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	4934000	USD
	sigi	Proceedsfromequityinvestmentsinexcessofcurrentyearearnings Proceedsfromequityinvestmentsinexcessofcurrentyearearnings	8488000	USD
	sigi	Proceedsfromequityinvestmentsinexcessofcurrentyearearnings Proceedsfromequityinvestmentsinexcessofcurrentyearearnings	2157000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	-32017000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	17478000	USD
	us-gaap	Gain Loss On Disposition Of Assets1 GainLossOnDispositionOfAssets1	-17000	USD
	us-gaap	Gain Loss On Disposition Of Assets1 GainLossOnDispositionOfAssets1	0	USD
	sigi	Increase Decrease In Reserves For Losses And Loss Expenses Net Of Reinsurance Recoverables IncreaseDecreaseInReservesForLossesAndLossExpensesNetOfReinsuranceRecoverables	101151000	USD
	sigi	Increase Decrease In Reserves For Losses And Loss Expenses Net Of Reinsurance Recoverables IncreaseDecreaseInReservesForLossesAndLossExpensesNetOfReinsuranceRecoverables	105082000	USD
	sigi	Increase Decrease In Unearned Premiums Net Of Prepaid Reinsurance IncreaseDecreaseInUnearnedPremiumsNetOfPrepaidReinsurance	89705000	USD
	sigi	Increase Decrease In Unearned Premiums Net Of Prepaid Reinsurance IncreaseDecreaseInUnearnedPremiumsNetOfPrepaidReinsurance	99152000	USD
	us-gaap	Increase Decrease In Income Taxes IncreaseDecreaseInIncomeTaxes	8340000	USD
	us-gaap	Increase Decrease In Income Taxes IncreaseDecreaseInIncomeTaxes	1698000	USD
	us-gaap	Increase Decrease In Premiums Receivable IncreaseDecreaseInPremiumsReceivable	44095000	USD
	us-gaap	Increase Decrease In Premiums Receivable IncreaseDecreaseInPremiumsReceivable	107190000	USD
	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	14269000	USD
	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	20516000	USD
	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	934000	USD
	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	1399000	USD
	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	-44082000	USD
	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	-29124000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	2753000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	22320000	USD
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-33770000	USD
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-13583000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	197385000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	165140000	USD
	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	961803000	USD
	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	891241000	USD
	sigi	Paymentstoacquirecommercialmortgageloans Paymentstoacquirecommercialmortgageloans	-17934000	USD
	sigi	Paymentstoacquirecommercialmortgageloans Paymentstoacquirecommercialmortgageloans	0	USD
	sigi	Paymentsto Acquire Equity Securities PaymentstoAcquireEquitySecurities	73879000	USD
	sigi	Paymentsto Acquire Equity Securities PaymentstoAcquireEquitySecurities	24699000	USD
	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	39400000	USD
	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	25822000	USD
	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	3368828000	USD
	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	3258852000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	302342000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	372159000	USD
	us-gaap	Proceeds From Sale And Collection Of Mortgage Notes Receivable ProceedsFromSaleAndCollectionOfMortgageNotesReceivable	54000	USD
	us-gaap	Proceeds From Sale And Collection Of Mortgage Notes Receivable ProceedsFromSaleAndCollectionOfMortgageNotesReceivable	0	USD
	sigi	Interest Paid Operatingand Investing Activities InterestPaidOperatingandInvestingActivities	14920000	USD
	sigi	Proceedsfrom Saleof Equity Securities ProceedsfromSaleofEquitySecurities	30094000	USD
	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	3278106000	USD
	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	3291878000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	1200000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	4643000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	461527000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	236705000	USD
	sigi	Proceedsfrom Saleof Equity Securities ProceedsfromSaleofEquitySecurities	1320000	USD
	us-gaap	Proceeds From Sale Of Other Investments ProceedsFromSaleOfOtherInvestments	53000	USD
	us-gaap	Proceeds From Sale Of Other Investments ProceedsFromSaleOfOtherInvestments	12609000	USD
	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	7349000	USD
	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	14489000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	12634000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	16985000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-422527000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-255022000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	26631000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	22940000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	6982000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	6715000	USD
	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	4731000	USD
	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	5100000	USD
	us-gaap	Proceeds From Debt Net Of Issuance Costs ProceedsFromDebtNetOfIssuanceCosts	387000000	USD
	us-gaap	Proceeds From Debt Net Of Issuance Costs ProceedsFromDebtNetOfIssuanceCosts	340757000	USD
	us-gaap	Repayments Of Debt RepaymentsOfDebt	135000000	USD
	us-gaap	Repayments Of Debt RepaymentsOfDebt	235000000	USD
	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	314000	USD
	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	596000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	222804000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	80606000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-2338000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-9276000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	7975000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	16919000	USD
CY2020Q2	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	5637000	USD
CY2019Q2	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	7643000	USD
	sigi	Percentof Commercial Mortgage Loans PercentofCommercialMortgageLoans	0.01
	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	314000	USD
	sigi	Interest Paid Operatingand Investing Activities InterestPaidOperatingandInvestingActivities	10512000	USD
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	0	USD
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	28000000	USD
	us-gaap	Operating Lease Payments OperatingLeasePayments	4443000	USD
	us-gaap	Operating Lease Payments OperatingLeasePayments	3994000	USD
	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	10000	USD
	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	7000	USD
	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	596000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	119000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	814000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	4358000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	12881000	USD
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CY2020Q2	us-gaap	Cash Cash	666000	USD
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CY2020Q2	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	-10395000	USD
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CY2020Q2	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	6358156000	USD
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CY2019Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	223372000	USD
CY2019Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	7738000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	6095620000	USD
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CY2020Q2	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Not Previously Recorded DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotPreviouslyRecorded	863000	USD
CY2020Q2	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Not To Sell Before Recovery Credit Loss Previously Recorded Expense Reversal DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal	-5720000	USD
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CY2020Q2	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Sell Before Recovery DebtSecuritiesAvailableForSaleAllowanceForCreditLossSellBeforeRecovery	-67000	USD
CY2020Q2	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	-10395000	USD
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	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Not Previously Recorded DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotPreviouslyRecorded	10930000	USD
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	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Securities Sold DebtSecuritiesAvailableForSaleAllowanceForCreditLossSecuritiesSold	-468000	USD
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CY2020Q2	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	-10395000	USD
CY2020Q2	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	315316000	USD
CY2020Q2	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearNetCarryingAmount	440000	USD
CY2020Q2	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Fair Value HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearFairValue	448000	USD
CY2020Q2	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	3639491000	USD
CY2020Q2	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount	16591000	USD
CY2020Q2	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	17843000	USD
CY2020Q2	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	2053058000	USD
CY2020Q2	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount	2511000	USD
CY2020Q2	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	2436000	USD
CY2020Q2	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	350291000	USD
CY2020Q2	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount	0	USD
CY2020Q2	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue	0	USD
CY2020Q2	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	6358156000	USD
CY2020Q2	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	19542000	USD
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CY2020Q2	us-gaap	Assets Held By Insurance Regulators AssetsHeldByInsuranceRegulators	27700000	USD
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CY2020Q2	sigi	Creditlossexpenseoninvestmentportfolio Creditlossexpenseoninvestmentportfolio	-4900000	USD
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CY2019Q2	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	2115000	USD
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CY2019Q2	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	2115000	USD
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CY2020Q2	sigi	Held To Maturity Securities Realized Gain HeldToMaturitySecuritiesRealizedGain	0	USD
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CY2019Q2	sigi	Short Term Investments Realized Gains ShortTermInvestmentsRealizedGains	2000	USD
	sigi	Short Term Investments Realized Gains ShortTermInvestmentsRealizedGains	337000	USD
	sigi	Short Term Investments Realized Gains ShortTermInvestmentsRealizedGains	16000	USD
CY2020Q2	sigi	Short Term Investments Realized Losses ShortTermInvestmentsRealizedLosses	1000	USD
CY2019Q2	sigi	Short Term Investments Realized Losses ShortTermInvestmentsRealizedLosses	1000	USD
	sigi	Short Term Investments Realized Losses ShortTermInvestmentsRealizedLosses	191000	USD
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CY2020Q2	sigi	Other Investments Realized Gains OtherInvestmentsRealizedGains	0	USD
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	sigi	Other Investments Realized Losses OtherInvestmentsRealizedLosses	5000	USD
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CY2020Q2	us-gaap	Finance Lease Liability FinanceLeaseLiability	539000	USD
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CY2020Q2	us-gaap	Finance Lease Liability FinanceLeaseLiability	539000	USD
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CY2020Q2	us-gaap	Long Term Debt And Capital Lease Obligations LongTermDebtAndCapitalLeaseObligations	550588000	USD
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CY2020Q2	sigi	Net Asset Value NetAssetValue	40400000	USD
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CY2020Q2	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	20727000	USD
CY2020Q2	sigi	Commercialmortgageloanfairvalue Commercialmortgageloanfairvalue	17949000	USD
CY2020Q2	us-gaap	Shortterm Debt Fair Value ShorttermDebtFairValue	252210000	USD
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	dei	Document Period End Date DocumentPeriodEndDate	2020-06-30
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CY2020Q2	us-gaap	Reinsurance Recoverables On Unpaid Losses Gross ReinsuranceRecoverablesOnUnpaidLossesGross	587127000	USD
CY2020Q2	us-gaap	Reinsurance Recoverables Allowance ReinsuranceRecoverablesAllowance	2396000	USD
CY2020Q2	us-gaap	Reinsurance Recoverables ReinsuranceRecoverables	584731000	USD
CY2020Q2	us-gaap	Reinsurance Recoverable Credit Quality Indicator Date Updated ReinsuranceRecoverableCreditQualityIndicatorDateUpdated	2020-06-30
CY2020Q1	us-gaap	Reinsurance Recoverables Allowance ReinsuranceRecoverablesAllowance	1502000	USD
CY2019Q4	us-gaap	Reinsurance Recoverables Allowance ReinsuranceRecoverablesAllowance	4400000	USD
CY2020Q2	us-gaap	Reinsurance Recoverable Credit Loss Expense Reversal ReinsuranceRecoverableCreditLossExpenseReversal	894000	USD
	us-gaap	Reinsurance Recoverable Credit Loss Expense Reversal ReinsuranceRecoverableCreditLossExpenseReversal	899000	USD
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CY2020Q2	us-gaap	Reinsurance Recoverable Allowance For Credit Loss Recovery ReinsuranceRecoverableAllowanceForCreditLossRecovery	0	USD
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CY2020Q2	us-gaap	Reinsurance Recoverables Allowance ReinsuranceRecoverablesAllowance	2396000	USD
CY2020Q2	us-gaap	Reinsurance Recoverables Allowance ReinsuranceRecoverablesAllowance	2396000	USD
CY2020Q2	us-gaap	Direct Premiums Written DirectPremiumsWritten	834643000	USD
CY2019Q2	us-gaap	Direct Premiums Written DirectPremiumsWritten	807367000	USD
	us-gaap	Direct Premiums Written DirectPremiumsWritten	1581074000	USD
	us-gaap	Direct Premiums Written DirectPremiumsWritten	1573761000	USD
CY2020Q2	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	6410000	USD
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CY2020Q2	us-gaap	Ceded Premiums Written CededPremiumsWritten	116301000	USD
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	us-gaap	Ceded Premiums Written CededPremiumsWritten	221448000	USD
	us-gaap	Ceded Premiums Written CededPremiumsWritten	211305000	USD
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CY2020Q2	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	6055000	USD
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	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	12228000	USD
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	us-gaap	Ceded Premiums Earned CededPremiumsEarned	218392000	USD
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CY2020Q2	us-gaap	Policyholder Benefits And Claims Incurred Gross PolicyholderBenefitsAndClaimsIncurredGross	451013000	USD
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CY2020Q2	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Ceded ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded	51364000	USD
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	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Ceded ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded	81733000	USD
	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Ceded ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded	102407000	USD
CY2020Q2	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	403949000	USD
CY2019Q2	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	380984000	USD
	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	804273000	USD
	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	767563000	USD
CY2020Q2	sigi	Policyholder Premium Credit PolicyholderPremiumCredit	0.15
	us-gaap	Schedule Of Liability For Unpaid Claims And Claims Adjustment Expense ScheduleOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense	<div style="line-height:120%;padding-top:4px;font-size:10pt;"><div style="padding-left:0px;text-indent:0px;line-height:normal;padding-top:10px;"><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman;font-size:10pt;width:100%;border-collapse:collapse;text-align:left;"><tr><td colspan="8"/></tr><tr><td style="width:74%;"/><td style="width:1%;"/><td style="width:1%;"/><td style="width:10%;"/><td style="width:1%;"/><td style="width:1%;"/><td style="width:11%;"/><td style="width:1%;"/></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:1px solid #000000;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:1px solid #000000;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="6" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:center;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;">Six Months ended June 30,</span></div></td></tr><tr><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">($ in thousands)</span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="3" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;">2020</span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">2019</span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Gross reserve for loss and loss expense, at beginning of year</span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;background-color:#ccffcc;border-top:1px solid #000000;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;">$</span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"><span>4,067,163</span></span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:1px solid #000000;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><span>3,893,868</span></span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Less: reinsurance recoverable on unpaid loss and loss expense, at beginning of year</span><span style="font-family:inherit;font-size:8pt;"><sup style="vertical-align:top;line-height:120%;font-size:5pt">1</sup></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"><span>547,066</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><span>537,388</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Net reserve for loss and loss expense, at beginning of year</span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"><span>3,520,097</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#ccffcc;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><span>3,356,480</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#ccffcc;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Incurred loss and loss expense for claims occurring in the:</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"> </span></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"> </span></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:12px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Current year</span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"><span>825,201</span></span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><span>783,938</span></span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:12px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Prior years</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"><span>(20,928</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-right:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;">)</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><span>(16,375</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-right:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">)</span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Total incurred loss and loss expense</span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"><span>804,273</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#ccffcc;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><span>767,563</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#ccffcc;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Paid loss and loss expense for claims occurring in the:</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"> </span></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"> </span></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:12px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Current year</span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"><span>221,422</span></span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><span>210,374</span></span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:12px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Prior years</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"><span>479,736</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><span>442,820</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Total paid loss and loss expense</span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"><span>701,158</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#ccffcc;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#ccffcc;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><span>653,194</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#ccffcc;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Net reserve for loss and loss expense, at end of period</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"><span>3,623,212</span></span></div></td><td style="vertical-align:bottom;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><span>3,470,849</span></span></div></td><td style="vertical-align:bottom;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;background-color:#d0ffd0;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Add: Reinsurance recoverable on unpaid loss and loss expense, at end of period</span></div></td><td style="vertical-align:bottom;background-color:#d0ffd0;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#d0ffd0;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"><span>553,694</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#d0ffd0;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;background-color:#d0ffd0;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#d0ffd0;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><span>556,203</span></span></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;background-color:#d0ffd0;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;">Gross reserve for loss and loss expense at end of period</span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:left;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;">$</span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;font-weight:bold;"><span>4,176,906</span></span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"> </span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><span>4,027,052</span></span></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;"><div style="text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;"><br/></span></div></td></tr></table></div><span style="font-family:inherit;font-size:10pt;"><br/></span></div><div style="line-height:120%;padding-top:4px;font-size:8pt;"><span style="font-family:inherit;font-size:8pt;"><sup style="vertical-align:top;line-height:120%;font-size:5pt">1</sup></span><span style="font-family:inherit;font-size:8pt;">Includes an adjustment of </span><span style="font-family:inherit;font-size:8pt;"><span>$2.9 million</span></span><span style="font-family:inherit;font-size:8pt;"> related to our adoption of ASU 2016-13. Refer to Note 2. "Adoption of Accounting Pronouncements" for additional information.</span></div>
CY2019Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	4067163000	USD
CY2018Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	3893868000	USD
CY2019Q4	us-gaap	Reinsurance Recoverable For Unpaid Claims And Claims Adjustments ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments	547066000	USD
CY2018Q4	us-gaap	Reinsurance Recoverable For Unpaid Claims And Claims Adjustments ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments	537388000	USD
CY2019Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	3520097000	USD
CY2018Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	3356480000	USD
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	825201000	USD
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	783938000	USD
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	804273000	USD
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	767563000	USD
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	221422000	USD
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	210374000	USD
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	479736000	USD
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	442820000	USD
	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	701158000	USD
	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	653194000	USD
CY2020Q2	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	3623212000	USD
CY2019Q2	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	3470849000	USD
CY2020Q2	us-gaap	Reinsurance Recoverable For Unpaid Claims And Claims Adjustments ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments	553694000	USD
CY2019Q2	us-gaap	Reinsurance Recoverable For Unpaid Claims And Claims Adjustments ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments	556203000	USD
CY2020Q2	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	4176906000	USD
CY2019Q2	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	4027052000	USD
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	825200000	USD
	us-gaap	Loss From Catastrophes LossFromCatastrophes	116400000	USD
	us-gaap	Loss From Catastrophes LossFromCatastrophes	50300000	USD
	sigi	Loss Reservefor Covid19 LossReserveforCOVID19	10000000.0	USD
	sigi	Loss Reservefor Covid19 LossReserveforCOVID19	10000000.0	USD
	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	4
CY2020Q2	us-gaap	Net Investment Income NetInvestmentIncome	34444000	USD
CY2019Q2	us-gaap	Net Investment Income NetInvestmentIncome	58505000	USD
	us-gaap	Net Investment Income NetInvestmentIncome	90411000	USD
	us-gaap	Net Investment Income NetInvestmentIncome	109123000	USD
CY2020Q2	us-gaap	Gain Loss On Investments GainLossOnInvestments	12649000	USD
CY2019Q2	us-gaap	Gain Loss On Investments GainLossOnInvestments	4027000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	-32017000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	17478000	USD
CY2020Q2	sigi	Total Investmentsrevenue TotalInvestmentsrevenue	47093000	USD
CY2019Q2	sigi	Total Investmentsrevenue TotalInvestmentsrevenue	62532000	USD
	sigi	Total Investmentsrevenue TotalInvestmentsrevenue	58394000	USD
	sigi	Total Investmentsrevenue TotalInvestmentsrevenue	126601000	USD
CY2020Q2	us-gaap	Revenues Revenues	682447000	USD
CY2019Q2	us-gaap	Revenues Revenues	708204000	USD
	us-gaap	Revenues Revenues	1347276000	USD
	us-gaap	Revenues Revenues	1407166000	USD
CY2020Q2	us-gaap	Net Investment Income NetInvestmentIncome	34444000	USD
CY2019Q2	us-gaap	Net Investment Income NetInvestmentIncome	58505000	USD
	us-gaap	Net Investment Income NetInvestmentIncome	90411000	USD
	us-gaap	Net Investment Income NetInvestmentIncome	109123000	USD
CY2020Q2	us-gaap	Gain Loss On Investments GainLossOnInvestments	12649000	USD
CY2019Q2	us-gaap	Gain Loss On Investments GainLossOnInvestments	4027000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	-32017000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	17478000	USD
CY2020Q2	sigi	Total Investmentsrevenue TotalInvestmentsrevenue	47093000	USD
CY2019Q2	sigi	Total Investmentsrevenue TotalInvestmentsrevenue	62532000	USD
	sigi	Total Investmentsrevenue TotalInvestmentsrevenue	58394000	USD
	sigi	Total Investmentsrevenue TotalInvestmentsrevenue	126601000	USD
CY2020Q2	sigi	Taxoninvestmentincome Taxoninvestmentincome	8558000	USD
CY2019Q2	sigi	Taxoninvestmentincome Taxoninvestmentincome	11729000	USD
	sigi	Taxoninvestmentincome Taxoninvestmentincome	9662000	USD
	sigi	Taxoninvestmentincome Taxoninvestmentincome	23849000	USD
CY2020Q2	sigi	Totalinvestmentsegmentincomeafterfederalincometax Totalinvestmentsegmentincomeafterfederalincometax	38535000	USD
CY2019Q2	sigi	Totalinvestmentsegmentincomeafterfederalincometax Totalinvestmentsegmentincomeafterfederalincometax	50803000	USD
	sigi	Totalinvestmentsegmentincomeafterfederalincometax Totalinvestmentsegmentincomeafterfederalincometax	48732000	USD
	sigi	Totalinvestmentsegmentincomeafterfederalincometax Totalinvestmentsegmentincomeafterfederalincometax	102752000	USD
CY2020Q2	sigi	Total Investmentsrevenue TotalInvestmentsrevenue	47093000	USD
CY2019Q2	sigi	Total Investmentsrevenue TotalInvestmentsrevenue	62532000	USD
	sigi	Total Investmentsrevenue TotalInvestmentsrevenue	58394000	USD
	sigi	Total Investmentsrevenue TotalInvestmentsrevenue	126601000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	58690000	USD
CY2020Q2	us-gaap	Interest Expense Debt InterestExpenseDebt	7928000	USD
CY2019Q2	us-gaap	Interest Expense Debt InterestExpenseDebt	7366000	USD
	us-gaap	Interest Expense Debt InterestExpenseDebt	15529000	USD
	us-gaap	Interest Expense Debt InterestExpenseDebt	18892000	USD
CY2020Q2	us-gaap	Other General Expense OtherGeneralExpense	6345000	USD
CY2019Q2	us-gaap	Other General Expense OtherGeneralExpense	9566000	USD
	us-gaap	Other General Expense OtherGeneralExpense	15405000	USD
	us-gaap	Other General Expense OtherGeneralExpense	21976000	USD
CY2020Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	42693000	USD
CY2019Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	90225000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	163919000	USD
CY2020Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	42693000	USD
CY2020Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	8510000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	34183000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	188768000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	39641000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	149127000	USD
CY2020Q2	sigi	Non Credit Portionof Other Than Temporary Impairments Recognizedin Other Comprehensive Income Gross NonCreditPortionofOtherThanTemporaryImpairmentsRecognizedinOtherComprehensiveIncomeGross	37479000	USD
CY2020Q2	sigi	Non Credit Portionof Other Than Temporary Impairments Recognizedin Other Comprehensive Income Tax NonCreditPortionofOtherThanTemporaryImpairmentsRecognizedinOtherComprehensiveIncomeTax	7871000	USD
CY2020Q2	sigi	Non Credit Portionof Other Than Temporary Impairments Recognizedin Other Comprehensive Income NonCreditPortionofOtherThanTemporaryImpairmentsRecognizedinOtherComprehensiveIncome	29608000	USD
CY2020Q2	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Before Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleBeforeTax	31000	USD
CY2020Q2	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleTax	6000	USD
CY2020Q2	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	25000	USD
CY2020Q2	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securitiesbefore Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesbeforeTax	-1686000	USD
CY2020Q2	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securities Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesTax	-354000	USD
CY2020Q2	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securities Netof Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesNetofTax	-1332000	USD
CY2020Q2	sigi	Debt Securities Availableforsale Allowancefor Credit Loss Gross DebtSecuritiesAvailableforsaleAllowanceforCreditLossGross	-4924000	USD
CY2020Q2	sigi	Debt Securities Availableforsale Allowancefor Credit Loss Tax DebtSecuritiesAvailableforsaleAllowanceforCreditLossTax	-1034000	USD
CY2020Q2	sigi	Debt Securities Availableforsale Allowancefor Credit Loss Net DebtSecuritiesAvailableforsaleAllowanceforCreditLossNet	-3890000	USD
CY2020Q2	sigi	Total Unrealized Gains Losses On Investment Securities Gross TotalUnrealizedGainsLossesOnInvestmentSecuritiesGross	219606000	USD
CY2020Q2	sigi	Total Unrealized Gains Losses On Investment Securities Tax TotalUnrealizedGainsLossesOnInvestmentSecuritiesTax	46118000	USD
CY2020Q2	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	-173488000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-753000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-158000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-595000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-753000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-158000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-595000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	220359000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	46276000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	174083000	USD
CY2020Q2	sigi	Comprehensive Income Loss Before Tax ComprehensiveIncomeLossBeforeTax	263052000	USD
CY2020Q2	sigi	Comprehensive Income Loss Tax ComprehensiveIncomeLossTax	54786000	USD
CY2020Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	208266000	USD
CY2019Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	90225000	USD
CY2019Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	17959000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	72266000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	83546000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	17544000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	66002000	USD
CY2019Q2	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Before Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleBeforeTax	21000	USD
CY2019Q2	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleTax	4000	USD
CY2019Q2	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	17000	USD
CY2019Q2	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securitiesbefore Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesbeforeTax	-1300000	USD
CY2019Q2	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securities Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesTax	-273000	USD
CY2019Q2	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securities Netof Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesNetofTax	-1027000	USD
CY2019Q2	sigi	Total Unrealized Gains Losses On Investment Securities Gross TotalUnrealizedGainsLossesOnInvestmentSecuritiesGross	82225000	USD
CY2019Q2	sigi	Total Unrealized Gains Losses On Investment Securities Tax TotalUnrealizedGainsLossesOnInvestmentSecuritiesTax	17267000	USD
CY2019Q2	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	-64958000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-664000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-140000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-524000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-664000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-140000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-524000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	82889000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	17407000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	65482000	USD
CY2019Q2	sigi	Comprehensive Income Loss Before Tax ComprehensiveIncomeLossBeforeTax	173114000	USD
CY2019Q2	sigi	Comprehensive Income Loss Tax ComprehensiveIncomeLossTax	35366000	USD
CY2019Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	137748000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	58690000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	9271000	USD
	us-gaap	Net Income Loss NetIncomeLoss	49419000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	94787000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	19905000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	74882000	USD
	sigi	Non Credit Portionof Other Than Temporary Impairments Recognizedin Other Comprehensive Income Gross NonCreditPortionofOtherThanTemporaryImpairmentsRecognizedinOtherComprehensiveIncomeGross	-27911000	USD
	sigi	Non Credit Portionof Other Than Temporary Impairments Recognizedin Other Comprehensive Income Tax NonCreditPortionofOtherThanTemporaryImpairmentsRecognizedinOtherComprehensiveIncomeTax	-5861000	USD
	sigi	Non Credit Portionof Other Than Temporary Impairments Recognizedin Other Comprehensive Income NonCreditPortionofOtherThanTemporaryImpairmentsRecognizedinOtherComprehensiveIncome	-22050000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Before Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleBeforeTax	6000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleTax	1000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	5000	USD
	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securitiesbefore Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesbeforeTax	9641000	USD
	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securities Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesTax	2025000	USD
	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securities Netof Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesNetofTax	7616000	USD
	sigi	Debt Securities Availableforsale Allowancefor Credit Loss Gross DebtSecuritiesAvailableforsaleAllowanceforCreditLossGross	10863000	USD
	sigi	Debt Securities Availableforsale Allowancefor Credit Loss Tax DebtSecuritiesAvailableforsaleAllowanceforCreditLossTax	2281000	USD
	sigi	Debt Securities Availableforsale Allowancefor Credit Loss Net DebtSecuritiesAvailableforsaleAllowanceforCreditLossNet	8582000	USD
	sigi	Total Unrealized Gains Losses On Investment Securities Gross TotalUnrealizedGainsLossesOnInvestmentSecuritiesGross	87374000	USD
	sigi	Total Unrealized Gains Losses On Investment Securities Tax TotalUnrealizedGainsLossesOnInvestmentSecuritiesTax	18349000	USD
	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	-69025000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-1507000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-316000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-1191000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-1507000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-316000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1191000	USD
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	88881000	USD
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	18665000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	70216000	USD
	sigi	Comprehensive Income Loss Before Tax ComprehensiveIncomeLossBeforeTax	147571000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	147315000	USD
	sigi	Comprehensive Income Loss Tax ComprehensiveIncomeLossTax	27936000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	119635000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	163919000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	30305000	USD
	us-gaap	Net Income Loss NetIncomeLoss	133614000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	186472000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	39157000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Before Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleBeforeTax	30000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleTax	6000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	24000	USD
	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securitiesbefore Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesbeforeTax	-2377000	USD
	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securities Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesTax	-499000	USD
	sigi	Oci Reclassification Adjustmentfrom Aoc Ifor Writedownof Securities Netof Tax OCIReclassificationAdjustmentfromAOCIforWritedownofSecuritiesNetofTax	-1878000	USD
	sigi	Total Unrealized Gains Losses On Investment Securities Gross TotalUnrealizedGainsLossesOnInvestmentSecuritiesGross	184065000	USD
	sigi	Total Unrealized Gains Losses On Investment Securities Tax TotalUnrealizedGainsLossesOnInvestmentSecuritiesTax	38652000	USD
	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	-145413000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-1328000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-279000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-1049000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-1328000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-279000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1049000	USD
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	185393000	USD
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	38931000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	146462000	USD
	sigi	Comprehensive Income Loss Before Tax ComprehensiveIncomeLossBeforeTax	349312000	USD
	sigi	Comprehensive Income Loss Tax ComprehensiveIncomeLossTax	69236000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	280076000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1191000	USD

Files In Submission

Name	View Source	Status
0000230557-20-000018-index-headers.html	Edgar Link	pending
0000230557-20-000018-index.html	Edgar Link	pending
0000230557-20-000018.txt	Edgar Link	pending
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report.css	Edgar Link	pending
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sigi-20200630.xsd	Edgar Link	pending
sigi-20200630_cal.xml	Edgar Link	unprocessable
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sigi-6302020x10q.htm	Edgar Link	pending
sigi-6302020x10q_htm.xml	Edgar Link	completed
sigi-ex116302020xq2.htm	Edgar Link	pending
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sigi-ex3126302020xq2.htm	Edgar Link	pending
sigi-ex3216302020xq2.htm	Edgar Link	pending
sigi-ex3226302020xq2.htm	Edgar Link	pending

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$SIGI
Selective Insurance Group Inc Stock $sigi

2020 Q3 Form 10-Q Financial Statement

#000023055720000018 Filed on July 31, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$SIGI Selective Insurance Group Inc Stock $sigi

2020 Q3 Form 10-Q Financial Statement

#000023055720000018 Filed on July 31, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$SIGI
Selective Insurance Group Inc Stock $sigi