$SIGI
Selective Insurance Group Inc Stock $sigi

$sigi Overview Financials Valuation SEC Filings Company Website

2019 Q4 Form 10-Q Financial Statement

#000023055719000028 Filed on October 31, 2019

Income Statement

Concept	2019 Q4	2019 Q3	2018 Q3
Revenue	$728.9M	$710.4M	$664.5M
YoY Change	13.36%	6.92%	6.95%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin	$2.900M	$8.600M	$7.500M
YoY Change	-14.71%	14.67%
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$12.90M	$136.6M	$124.5M
YoY Change	30.3%	9.69%	5.39%
% of Gross Profit
Operating Expenses	$620.2M	$631.8M	$591.3M
YoY Change	6.05%	6.85%	7.92%
Operating Profit
YoY Change
Interest Expense	-$7.400M	-$7.400M	-$6.100M
YoY Change	21.31%	21.31%	0.0%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$101.3M	$71.18M	$67.13M
YoY Change	94.29%	6.03%	-0.27%
Income Tax	$19.40M	$15.03M	$11.70M
% Of Pretax Income	19.15%	21.11%	17.42%
Net Earnings	$81.86M	$56.15M	$55.44M
YoY Change	78.89%	1.29%	18.66%
Net Earnings / Revenue	11.23%	7.9%	8.34%
Basic Earnings Per Share	$1.38	$0.94	$0.94
Diluted Earnings Per Share	$1.36	$0.93	$0.93
COMMON SHARES
Basic Shares Outstanding	59.40M shares	59.37M shares	58.84M shares
Diluted Shares Outstanding

Balance Sheet

Concept	2019 Q4	2019 Q3	2018 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$7.975M	$10.16M	$12.83M
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	$77.41M	$76.42M	$64.23M
YoY Change	18.64%	18.99%	-3.19%
Goodwill	$7.800M	$7.849M	$7.849M
YoY Change	-0.62%	0.0%	0.0%
Intangibles
YoY Change
Long-Term Investments	$6.689B	$6.552B	$5.861B
YoY Change	12.21%	11.78%	2.63%
Other Assets	$14.50M	$15.20M	$64.70M
YoY Change	-79.29%	-76.51%	22.31%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$8.797B	$8.719B	$7.987B
YoY Change	10.62%	9.17%	2.24%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$154.3M	$129.7M	$95.40M
YoY Change	32.22%	35.95%	-15.65%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$157.3M	$132.4M	$107.5M
YoY Change	33.31%	23.16%	-10.27%
LONG-TERM LIABILITIES
Long-Term Debt	$550.6M	$550.7M	$439.4M
YoY Change	25.28%	25.33%	0.09%
Other Long-Term Liabilities	$304.0M	$273.2M	$292.4M
YoY Change	9.51%	-6.57%	-9.84%
Total Long-Term Liabilities	$854.6M	$823.9M	$731.8M
YoY Change	19.17%	12.59%	-4.13%
TOTAL LIABILITIES
Total Short-Term Liabilities	$157.3M	$132.4M	$107.5M
Total Long-Term Liabilities	$854.6M	$823.9M	$731.8M
Total Liabilities	$6.602B	$6.582B	$6.248B
YoY Change	7.16%	5.34%	2.22%
SHAREHOLDERS EQUITY
Retained Earnings	$2.081B	$2.012B	$1.825B
YoY Change	11.95%	10.3%	8.67%
Common Stock	$625.5M	$619.2M	$591.0M
YoY Change	4.95%	4.77%	4.22%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$592.8M	$592.7M	$584.5M
YoY Change	1.4%	1.4%	1.11%
Treasury Stock Shares	44.02M shares	44.02M shares	43.90M shares
Shareholders Equity	$2.195B	$2.137B	$1.739B
YoY Change
Total Liabilities & Shareholders Equity	$8.797B	$8.719B	$7.987B
YoY Change	10.62%	9.17%	2.24%

Cashflow Statement

Concept	2019 Q4	2019 Q3	2018 Q3
OPERATING ACTIVITIES
Net Income	$81.86M	$56.15M	$55.44M
YoY Change	78.89%	1.29%	18.66%
Depreciation, Depletion And Amortization	$12.90M	$136.6M	$124.5M
YoY Change	30.3%	9.69%	5.39%
Cash From Operating Activities	$161.3M	$151.1M	$200.2M
YoY Change	-0.68%	-24.53%	2.77%
INVESTING ACTIVITIES
Capital Expenditures	-$6.600M	-$7.400M	-$4.500M
YoY Change	34.69%	64.44%	-6.25%
Acquisitions
YoY Change
Other Investing Activities	-$146.0M	-$128.6M	-$186.5M
YoY Change	1.81%	-31.05%	4.31%
Cash From Investing Activities	-$152.6M	-$136.0M	-$191.0M
YoY Change	2.9%	-28.8%	4.03%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-10.80M	-12.60M	-12.90M
YoY Change	8.0%	-2.33%	38.71%
NET CHANGE
Cash From Operating Activities	161.3M	151.1M	200.2M
Cash From Investing Activities	-152.6M	-136.0M	-191.0M
Cash From Financing Activities	-10.80M	-12.60M	-12.90M
Net Change In Cash	-2.100M	2.500M	-3.700M
YoY Change	-151.22%	-167.57%	-294.74%
FREE CASH FLOW
Cash From Operating Activities	$161.3M	$151.1M	$200.2M
Capital Expenditures	-$6.600M	-$7.400M	-$4.500M
Free Cash Flow	$167.9M	$158.5M	$204.7M
YoY Change	0.36%	-22.57%	2.56%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
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CY2018Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	5270798000	USD
	dei	Amendment Flag AmendmentFlag	false
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q3
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2019
	dei	Entity Central Index Key EntityCentralIndexKey	0000230557
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Small Business EntitySmallBusiness	false
CY2018Q4	sigi	Htm Securities Percentof Invested Assets HTMSecuritiesPercentofInvestedAssets	0.01
CY2018Q4	sigi	Maximumexposuretocreditconcentrationriskofthe Companysstockholdersequityotherthancertain U.S.Governmentagencies MaximumexposuretocreditconcentrationriskoftheCompanysstockholdersequityotherthancertainU.S.governmentagencies	0.10
CY2018Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	211657000	USD
CY2019Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	5706656000	USD
CY2018Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	2
CY2019Q3	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	2
CY2018Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	360000000	shares
CY2019Q3	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	360000000	shares
CY2018Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	102848394	shares
CY2019Q3	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	103421301	shares
CY2018Q4	us-gaap	Equity Securities Fv Ni Cost EquitySecuritiesFvNiCost	138144000	USD
CY2019Q3	us-gaap	Equity Securities Fv Ni Cost EquitySecuritiesFvNiCost	77779000	USD
CY2019Q1	us-gaap	Finance Lease Liability FinanceLeaseLiability	900000	USD
CY2018Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	43899840	shares
CY2019Q3	us-gaap	Treasury Stock Shares TreasuryStockShares	44021732	shares
	dei	Document Type DocumentType	10-Q
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Document Period End Date DocumentPeriodEndDate	2019-09-30
	dei	Document Transition Report DocumentTransitionReport	false
	dei	Entity File Number EntityFileNumber	001-33067
	dei	Entity Registrant Name EntityRegistrantName	SELECTIVE INSURANCE GROUP, INC
CY2019Q3	us-gaap	Premiums Receivable Allowance For Doubtful Accounts PremiumsReceivableAllowanceForDoubtfulAccounts	7800000	USD
	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	NJ
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	22-2168890
CY2018Q3	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0
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CY2018Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	5000000	shares
CY2019Q3	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	5000000	shares
CY2018Q3	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
	dei	Entity Address Address Line1 EntityAddressAddressLine1	40 Wantage Avenue
	dei	Entity Address City Or Town EntityAddressCityOrTown	Branchville
CY2018Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2019Q3	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
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	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	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
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	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	235097000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	159586000	USD
CY2019Q3	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	13805000	USD
CY2018Q3	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	10314000	USD
	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	44344000	USD
	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	23529000	USD
CY2019Q3	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	1223000	USD
CY2018Q3	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	1381000	USD
	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	989000	USD
	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	2878000	USD
CY2019Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	15028000	USD
CY2018Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11695000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	45333000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	26407000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	56150000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	55435000	USD
	us-gaap	Net Income Loss NetIncomeLoss	189764000	USD
	us-gaap	Net Income Loss NetIncomeLoss	133179000	USD
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.94
CY2018Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.94
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.20
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.26
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.93
CY2018Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.93
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.16
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.23
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	56150000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	55435000	USD
	us-gaap	Net Income Loss NetIncomeLoss	189764000	USD
	us-gaap	Net Income Loss NetIncomeLoss	133179000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	27168000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-17036000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	174483000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-103389000	USD
CY2019Q3	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	2000	USD
CY2018Q3	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	6000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	26000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	22000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-2229000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-8563000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-351000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-14424000	USD
CY2019Q3	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	-29395000	USD
CY2018Q3	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	8479000	USD
	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	-174808000	USD
	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	88987000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-525000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-420000	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	-1574000	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	-1260000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-525000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-420000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1574000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1260000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	29920000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-8059000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	176382000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-87727000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	86070000	USD
CY2018Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	47376000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	366146000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	45452000	USD
CY2019Q3	us-gaap	Stockholders Equity StockholdersEquity	2137376000	USD
CY2018Q3	us-gaap	Stockholders Equity StockholdersEquity	1738520000	USD
CY2019Q3	us-gaap	Stockholders Equity StockholdersEquity	2137376000	USD
CY2018Q3	us-gaap	Stockholders Equity StockholdersEquity	1738520000	USD
CY2019Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.20
CY2018Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.18
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.60
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.54
CY2019Q2	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	59328108	shares
CY2018Q2	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	58835052	shares
CY2018Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	58948554	shares
CY2017Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	58495122	shares
CY2019Q3	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	4738	shares
CY2018Q3	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	5310	shares
	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	15650	shares
	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	17683	shares
CY2019Q3	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	83979	shares
CY2018Q3	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	51482	shares
	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	557257	shares
	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	484491	shares
CY2019Q3	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	17256	shares
CY2018Q3	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	2859	shares
	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	121892	shares
	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	108311	shares
CY2019Q3	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	59399569	shares
CY2018Q3	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	58888985	shares
CY2019Q3	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	59399569	shares
CY2018Q3	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	58888985	shares
	us-gaap	Net Income Loss NetIncomeLoss	189764000	USD
	us-gaap	Net Income Loss NetIncomeLoss	133179000	USD
	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	42346000	USD
	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	34961000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	15857000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	12150000	USD
	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	8832000	USD
	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	4243000	USD
	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	2267000	USD
	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	3210000	USD
	us-gaap	Gain Loss On Disposition Of Assets1 GainLossOnDispositionOfAssets1	21000	USD
	us-gaap	Gain Loss On Disposition Of Assets1 GainLossOnDispositionOfAssets1	-62000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	15295000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	-16988000	USD
	sigi	Increase Decrease In Reserves For Losses And Loss Expenses Net Of Reinsurance Recoverables IncreaseDecreaseInReservesForLossesAndLossExpensesNetOfReinsuranceRecoverables	134951000	USD
	sigi	Increase Decrease In Reserves For Losses And Loss Expenses Net Of Reinsurance Recoverables IncreaseDecreaseInReservesForLossesAndLossExpensesNetOfReinsuranceRecoverables	144920000	USD
	sigi	Increase Decrease In Unearned Premiums Net Of Prepaid Reinsurance IncreaseDecreaseInUnearnedPremiumsNetOfPrepaidReinsurance	122460000	USD
	sigi	Increase Decrease In Unearned Premiums Net Of Prepaid Reinsurance IncreaseDecreaseInUnearnedPremiumsNetOfPrepaidReinsurance	120535000	USD
	us-gaap	Increase Decrease In Income Taxes IncreaseDecreaseInIncomeTaxes	2408000	USD
	us-gaap	Increase Decrease In Income Taxes IncreaseDecreaseInIncomeTaxes	18339000	USD
	us-gaap	Increase Decrease In Premiums Receivable IncreaseDecreaseInPremiumsReceivable	89962000	USD
	us-gaap	Increase Decrease In Premiums Receivable IncreaseDecreaseInPremiumsReceivable	79894000	USD
	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	26627000	USD
	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	22978000	USD
	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	1460000	USD
	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	-72000	USD
	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	-16261000	USD
	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	-36498000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	35810000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	13881000	USD
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	414000	USD
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-34437000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	316199000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	292485000	USD
	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	0	USD
	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	7150000	USD
	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	1330827000	USD
	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	1974253000	USD
	sigi	Paymentsto Acquire Equity Securities PaymentstoAcquireEquitySecurities	40233000	USD
	sigi	Paymentsto Acquire Equity Securities PaymentstoAcquireEquitySecurities	57834000	USD
	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	41248000	USD
	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	47238000	USD
	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	4108414000	USD
	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	2711360000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	461825000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	1382677000	USD
	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	4106643000	USD
	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	2572399000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	10062000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	3923000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	413220000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	456037000	USD
	sigi	Proceedsfrom Saleof Equity Securities ProceedsfromSaleofEquitySecurities	125302000	USD
	sigi	Proceedsfrom Saleof Equity Securities ProceedsfromSaleofEquitySecurities	79676000	USD
	us-gaap	Proceeds From Sale Of Other Investments ProceedsFromSaleOfOtherInvestments	18016000	USD
	us-gaap	Proceeds From Sale Of Other Investments ProceedsFromSaleOfOtherInvestments	3497000	USD
	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	19054000	USD
	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	23420000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	24424000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	11150000	USD
	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	35000	USD
	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	0	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-390989000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-287356000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	34440000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	30694000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	8071000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	6423000	USD
	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	5599000	USD
	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	5001000	USD
	us-gaap	Proceeds From Debt Net Of Issuance Costs ProceedsFromDebtNetOfIssuanceCosts	355757000	USD
	us-gaap	Proceeds From Debt Net Of Issuance Costs ProceedsFromDebtNetOfIssuanceCosts	130000000	USD
	us-gaap	Repayments Of Debt RepaymentsOfDebt	250000000	USD
	us-gaap	Repayments Of Debt RepaymentsOfDebt	130000000	USD
	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	811000	USD
	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	4891000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	68034000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-37007000	USD
	sigi	Cashand Restricted Cash Period Increase Decrease CashandRestrictedCashPeriodIncreaseDecrease	-6756000	USD
	sigi	Cashand Restricted Cash Period Increase Decrease CashandRestrictedCashPeriodIncreaseDecrease	-31878000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	16919000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	44710000	USD
CY2019Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	10163000	USD
CY2018Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	12832000	USD
	us-gaap	Interest Paid Net InterestPaidNet	19261000	USD
	us-gaap	Interest Paid Net InterestPaidNet	15449000	USD
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	42000000	USD
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	7193000	USD
	us-gaap	Operating Lease Payments OperatingLeasePayments	6062000	USD
	us-gaap	Operating Lease Payments OperatingLeasePayments	0	USD
	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	12000	USD
	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	0	USD
	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	811000	USD
	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	4891000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	824000	USD
	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	4114000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	13648000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	0	USD
	us-gaap	Noncash Or Part Noncash Acquisition Fixed Assets Acquired1 NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1	108000	USD
	us-gaap	Noncash Or Part Noncash Acquisition Fixed Assets Acquired1 NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1	0	USD
CY2019Q3	us-gaap	Cash Cash	516000	USD
CY2018Q4	us-gaap	Cash Cash	505000	USD
CY2019Q3	us-gaap	Restricted Cash RestrictedCash	9647000	USD
CY2018Q4	us-gaap	Restricted Cash RestrictedCash	16414000	USD
CY2019Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	10163000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	16919000	USD
CY2019Q3	sigi	Htm Securities Percentof Invested Assets HTMSecuritiesPercentofInvestedAssets	0.01
CY2019Q3	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	7747000	USD
CY2019Q3	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	26900000	USD
CY2019Q3	sigi	Net Unrealized Unrecognized Gains Losseson Heldto Maturity Securities NetUnrealizedUnrecognizedGainsLossesonHeldtoMaturitySecurities	1500000	USD
CY2018Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	37100000	USD
CY2018Q4	sigi	Net Unrealized Unrecognized Gains Losseson Heldto Maturity Securities NetUnrealizedUnrecognizedGainsLossesonHeldtoMaturitySecurities	1300000	USD
CY2019Q3	sigi	Unrealized Unrecognized Loss UnrealizedUnrecognizedLoss	100000	USD
CY2018Q4	sigi	Unrealized Unrecognized Loss UnrealizedUnrecognizedLoss	200000	USD
CY2019Q3	us-gaap	Available For Sale Securities Amortized Cost AvailableForSaleSecuritiesAmortizedCost	5706656000	USD
CY2019Q3	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	231328000	USD
CY2019Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	5930237000	USD
CY2018Q4	us-gaap	Available For Sale Securities Amortized Cost AvailableForSaleSecuritiesAmortizedCost	5270798000	USD
CY2018Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	47369000	USD
CY2018Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	45067000	USD
CY2018Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	5273100000	USD
CY2019Q3	sigi	Percent Of Securities In An Unrealized Unrecognized Loss Position PercentOfSecuritiesInAnUnrealizedUnrecognizedLossPosition	0.01
CY2018Q4	sigi	Percent Of Securities In An Unrealized Unrecognized Loss Position PercentOfSecuritiesInAnUnrealizedUnrecognizedLossPosition	0.02
CY2019Q3	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	310387000	USD
CY2019Q3	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearNetCarryingAmount	4754000	USD
CY2019Q3	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Fair Value HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearFairValue	4773000	USD
CY2019Q3	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	3296126000	USD
CY2019Q3	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount	16334000	USD
CY2019Q3	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	17589000	USD
CY2019Q3	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	2191633000	USD
CY2019Q3	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount	5837000	USD
CY2019Q3	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	5994000	USD
CY2019Q3	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	132091000	USD
CY2019Q3	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount	0	USD
CY2019Q3	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue	0	USD
CY2019Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	5930237000	USD
CY2019Q3	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	26925000	USD
CY2019Q3	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	28356000	USD
CY2019Q3	us-gaap	Assets Held By Insurance Regulators AssetsHeldByInsuranceRegulators	27100000	USD
CY2019Q3	us-gaap	Security Owned And Pledged As Collateral Fair Value SecurityOwnedAndPledgedAsCollateralFairValue	192500000	USD
CY2019Q3	sigi	Maximumexposuretocreditconcentrationriskofthe Companysstockholdersequityotherthancertain U.S.Governmentagencies MaximumexposuretocreditconcentrationriskoftheCompanysstockholdersequityotherthancertainU.S.governmentagencies	0.10
CY2019Q3	us-gaap	Net Investment Income NetInvestmentIncome	55826000	USD
CY2018Q3	us-gaap	Net Investment Income NetInvestmentIncome	52443000	USD
	us-gaap	Net Investment Income NetInvestmentIncome	164949000	USD
	us-gaap	Net Investment Income NetInvestmentIncome	141227000	USD
CY2019Q3	us-gaap	Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet	2300000	USD
CY2018Q3	us-gaap	Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet	1400000	USD
	us-gaap	Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet	3400000	USD
	us-gaap	Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet	5500000	USD
CY2019Q3	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	20425000	USD
CY2018Q3	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-751000	USD
	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	26752000	USD
	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	4034000	USD
CY2019Q3	us-gaap	Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet	2291000	USD
CY2018Q3	us-gaap	Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet	1426000	USD
	us-gaap	Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet	3366000	USD
	us-gaap	Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet	5459000	USD
CY2019Q3	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	18134000	USD
CY2018Q3	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	-2177000	USD
	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	23386000	USD
	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	-1425000	USD
CY2019Q3	sigi	Unrealized Gains Losseson Equity Securities UnrealizedGainsLossesonEquitySecurities	-20317000	USD
CY2018Q3	sigi	Unrealized Gains Losseson Equity Securities UnrealizedGainsLossesonEquitySecurities	-2610000	USD
	sigi	Unrealized Gains Losseson Equity Securities UnrealizedGainsLossesonEquitySecurities	-8091000	USD
	sigi	Unrealized Gains Losseson Equity Securities UnrealizedGainsLossesonEquitySecurities	-15563000	USD
CY2019Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	-2183000	USD
CY2018Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	-4787000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	15295000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	-16988000	USD
CY2019Q3	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	1109000	USD
CY2018Q3	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	5476000	USD
	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	1805000	USD
	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	4199000	USD
CY2019Q3	sigi	Unrealized Gain Losson Equity Securities Sold UnrealizedGainLossonEquitySecuritiesSold	-21426000	USD
CY2018Q3	sigi	Unrealized Gain Losson Equity Securities Sold UnrealizedGainLossonEquitySecuritiesSold	-8086000	USD
	sigi	Unrealized Gain Losson Equity Securities Sold UnrealizedGainLossonEquitySecuritiesSold	-9896000	USD
	sigi	Unrealized Gain Losson Equity Securities Sold UnrealizedGainLossonEquitySecuritiesSold	-19762000	USD
CY2019Q3	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	-20317000	USD
CY2018Q3	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	-2610000	USD
	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	-8091000	USD
	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	-15563000	USD
CY2019Q3	sigi	Held To Maturity Securities Realized Gain HeldToMaturitySecuritiesRealizedGain	0	USD
CY2018Q3	sigi	Held To Maturity Securities Realized Gain HeldToMaturitySecuritiesRealizedGain	0	USD
	sigi	Held To Maturity Securities Realized Gain HeldToMaturitySecuritiesRealizedGain	1000	USD
	sigi	Held To Maturity Securities Realized Gain HeldToMaturitySecuritiesRealizedGain	2000	USD
CY2019Q3	sigi	Held To Maturity Securities Disposal Security Realized Loss HeldToMaturitySecuritiesDisposalSecurityRealizedLoss	0	USD
CY2018Q3	sigi	Held To Maturity Securities Disposal Security Realized Loss HeldToMaturitySecuritiesDisposalSecurityRealizedLoss	0	USD
	sigi	Held To Maturity Securities Disposal Security Realized Loss HeldToMaturitySecuritiesDisposalSecurityRealizedLoss	15000	USD
	sigi	Held To Maturity Securities Disposal Security Realized Loss HeldToMaturitySecuritiesDisposalSecurityRealizedLoss	0	USD
CY2019Q3	us-gaap	Equity Securities Fv Ni Realized Gain EquitySecuritiesFvNiRealizedGain	21630000	USD
CY2018Q3	us-gaap	Equity Securities Fv Ni Realized Gain EquitySecuritiesFvNiRealizedGain	10584000	USD
	us-gaap	Equity Securities Fv Ni Realized Gain EquitySecuritiesFvNiRealizedGain	24868000	USD
	us-gaap	Equity Securities Fv Ni Realized Gain EquitySecuritiesFvNiRealizedGain	20209000	USD
CY2019Q3	us-gaap	Equity Securities Fv Ni Realized Loss EquitySecuritiesFvNiRealizedLoss	28000	USD
CY2018Q3	us-gaap	Equity Securities Fv Ni Realized Loss EquitySecuritiesFvNiRealizedLoss	1919000	USD
	sigi	Short Term Investments Realized Gains ShortTermInvestmentsRealizedGains	6000	USD
CY2019Q3	sigi	Short Term Investments Realized Losses ShortTermInvestmentsRealizedLosses	38000	USD
	us-gaap	Equity Securities Fv Ni Realized Loss EquitySecuritiesFvNiRealizedLoss	135000	USD
	us-gaap	Equity Securities Fv Ni Realized Loss EquitySecuritiesFvNiRealizedLoss	2249000	USD
CY2019Q3	sigi	Short Term Investments Realized Gains ShortTermInvestmentsRealizedGains	2000	USD
CY2018Q3	sigi	Short Term Investments Realized Gains ShortTermInvestmentsRealizedGains	3000	USD
	sigi	Short Term Investments Realized Gains ShortTermInvestmentsRealizedGains	18000	USD
CY2018Q3	sigi	Short Term Investments Realized Losses ShortTermInvestmentsRealizedLosses	1000	USD
	sigi	Short Term Investments Realized Losses ShortTermInvestmentsRealizedLosses	39000	USD
	sigi	Short Term Investments Realized Losses ShortTermInvestmentsRealizedLosses	5000	USD
CY2019Q3	sigi	Other Investments Realized Gains OtherInvestmentsRealizedGains	0	USD
CY2018Q3	sigi	Other Investments Realized Gains OtherInvestmentsRealizedGains	0	USD
	sigi	Other Investments Realized Gains OtherInvestmentsRealizedGains	7000	USD
	sigi	Other Investments Realized Gains OtherInvestmentsRealizedGains	0	USD
CY2019Q3	sigi	Other Investments Realized Losses OtherInvestmentsRealizedLosses	0	USD
CY2018Q3	sigi	Other Investments Realized Losses OtherInvestmentsRealizedLosses	5000	USD
	sigi	Other Investments Realized Losses OtherInvestmentsRealizedLosses	30000	USD
	sigi	Other Investments Realized Losses OtherInvestmentsRealizedLosses	5000	USD
CY2019Q3	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	20425000	USD
CY2018Q3	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-751000	USD
	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	26752000	USD
	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	4034000	USD
CY2019Q3	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	89700000	USD
CY2018Q3	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	444400000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	461800000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	1382700000	USD
CY2019Q3	sigi	Proceedsfrom Saleof Equity Securities ProceedsfromSaleofEquitySecurities	95200000	USD
CY2018Q3	sigi	Proceedsfrom Saleof Equity Securities ProceedsfromSaleofEquitySecurities	36100000	USD
	sigi	Proceedsfrom Saleof Equity Securities ProceedsfromSaleofEquitySecurities	125300000	USD
	sigi	Proceedsfrom Saleof Equity Securities ProceedsfromSaleofEquitySecurities	79700000	USD
CY2019Q3	us-gaap	Finance Lease Liability FinanceLeaseLiability	904000	USD
CY2018Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	0	USD
CY2019Q3	us-gaap	Debt Instrument Unamortized Discount Premium And Debt Issuance Costs Net DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet	10235000	USD
CY2019Q3	us-gaap	Long Term Debt And Capital Lease Obligations Including Current Maturities LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities	550669000	USD
CY2018Q4	us-gaap	Long Term Debt LongTermDebt	439540000	USD
CY2019Q3	us-gaap	Long Term Debt Fair Value LongTermDebtFairValue	657267000	USD
CY2018Q4	us-gaap	Long Term Debt Fair Value LongTermDebtFairValue	448622000	USD
CY2019Q3	us-gaap	Finance Lease Liability FinanceLeaseLiability	904000	USD
CY2018Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	0	USD
CY2019Q3	us-gaap	Long Term Debt And Capital Lease Obligations Including Current Maturities LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities	550669000	USD
CY2018Q4	us-gaap	Long Term Debt LongTermDebt	439540000	USD
CY2019Q3	sigi	Net Asset Value NetAssetValue	33200000	USD
CY2018Q4	sigi	Net Asset Value NetAssetValue	37300000	USD
CY2019Q3	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	28356000	USD
CY2018Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	38317000	USD
CY2019Q3	us-gaap	Direct Premiums Written DirectPremiumsWritten	785680000	USD
CY2018Q3	us-gaap	Direct Premiums Written DirectPremiumsWritten	752834000	USD
	us-gaap	Direct Premiums Written DirectPremiumsWritten	2359441000	USD
	us-gaap	Direct Premiums Written DirectPremiumsWritten	2220431000	USD
CY2019Q3	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	6882000	USD
CY2018Q3	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	7084000	USD
	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	18770000	USD
	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	19891000	USD
CY2019Q3	us-gaap	Ceded Premiums Written CededPremiumsWritten	115634000	USD
CY2018Q3	us-gaap	Ceded Premiums Written CededPremiumsWritten	108250000	USD
	us-gaap	Ceded Premiums Written CededPremiumsWritten	326939000	USD
	us-gaap	Ceded Premiums Written CededPremiumsWritten	308846000	USD
CY2019Q3	us-gaap	Premiums Written Net PremiumsWrittenNet	676928000	USD
CY2018Q3	us-gaap	Premiums Written Net PremiumsWrittenNet	651668000	USD
	us-gaap	Premiums Written Net PremiumsWrittenNet	2051272000	USD
	us-gaap	Premiums Written Net PremiumsWrittenNet	1931476000	USD
CY2019Q3	us-gaap	Direct Premiums Earned DirectPremiumsEarned	752872000	USD
CY2018Q3	us-gaap	Direct Premiums Earned DirectPremiumsEarned	706497000	USD
	us-gaap	Direct Premiums Earned DirectPremiumsEarned	2221257000	USD
	us-gaap	Direct Premiums Earned DirectPremiumsEarned	2086953000	USD
CY2019Q3	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	6356000	USD
CY2018Q3	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	6484000	USD
	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	18660000	USD
	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	19220000	USD
CY2019Q3	us-gaap	Ceded Premiums Earned CededPremiumsEarned	105608000	USD
CY2018Q3	us-gaap	Ceded Premiums Earned CededPremiumsEarned	98704000	USD
	us-gaap	Ceded Premiums Earned CededPremiumsEarned	311105000	USD
	us-gaap	Ceded Premiums Earned CededPremiumsEarned	295232000	USD
CY2019Q3	us-gaap	Premiums Earned Net Property And Casualty PremiumsEarnedNetPropertyAndCasualty	653620000	USD
CY2018Q3	us-gaap	Premiums Earned Net Property And Casualty PremiumsEarnedNetPropertyAndCasualty	614277000	USD
	us-gaap	Premiums Earned Net Property And Casualty PremiumsEarnedNetPropertyAndCasualty	1928812000	USD
	us-gaap	Premiums Earned Net Property And Casualty PremiumsEarnedNetPropertyAndCasualty	1810941000	USD
CY2019Q3	us-gaap	Policyholder Benefits And Claims Incurred Gross PolicyholderBenefitsAndClaimsIncurredGross	437618000	USD
CY2018Q3	us-gaap	Policyholder Benefits And Claims Incurred Gross PolicyholderBenefitsAndClaimsIncurredGross	477427000	USD
	us-gaap	Policyholder Benefits And Claims Incurred Gross PolicyholderBenefitsAndClaimsIncurredGross	1297975000	USD
	us-gaap	Policyholder Benefits And Claims Incurred Gross PolicyholderBenefitsAndClaimsIncurredGross	1289357000	USD
CY2019Q3	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Assumed ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountAssumed	4362000	USD
CY2018Q3	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Assumed ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountAssumed	6529000	USD
	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Assumed ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountAssumed	13975000	USD
	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Assumed ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountAssumed	16897000	USD
CY2019Q3	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Ceded ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded	43305000	USD
CY2018Q3	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Ceded ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded	104757000	USD
	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Ceded ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded	145712000	USD
	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Ceded ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded	175786000	USD
CY2019Q3	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	398675000	USD
CY2018Q3	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	379199000	USD
	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	1166238000	USD
	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	1130468000	USD
	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;">Nine Months ended September 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;">2019</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;">2018</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>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><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>3,771,240</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></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>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><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>585,855</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>3,356,480</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>3,185,385</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>1,200,878</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>1,148,032</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>(34,640</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>(17,564</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>1,166,238</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>1,130,468</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>384,436</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>369,036</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>631,589</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>610,734</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>1,016,025</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>979,770</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>3,506,693</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>3,336,083</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>548,938</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>589,072</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>4,055,631</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>3,925,155</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>
CY2018Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	3893868000	USD
CY2017Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	3771240000	USD
CY2018Q4	us-gaap	Reinsurance Recoverable For Unpaid Claims And Claims Adjustments ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments	537388000	USD
CY2017Q4	us-gaap	Reinsurance Recoverable For Unpaid Claims And Claims Adjustments ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments	585855000	USD
CY2018Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	3356480000	USD
CY2017Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	3185385000	USD
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	1200878000	USD
	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	1148032000	USD
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	1166238000	USD
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	1130468000	USD
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	384436000	USD
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	369036000	USD
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	631589000	USD
	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	610734000	USD
	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	1016025000	USD
	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	979770000	USD
CY2019Q3	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	3506693000	USD
CY2018Q3	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	3336083000	USD
CY2019Q3	us-gaap	Reinsurance Recoverable For Unpaid Claims And Claims Adjustments ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments	548938000	USD
CY2018Q3	us-gaap	Reinsurance Recoverable For Unpaid Claims And Claims Adjustments ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments	589072000	USD
CY2019Q3	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	4055631000	USD
CY2018Q3	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	3925155000	USD
	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	4
CY2019Q3	us-gaap	Net Investment Income NetInvestmentIncome	55826000	USD
CY2018Q3	us-gaap	Net Investment Income NetInvestmentIncome	52443000	USD
	us-gaap	Net Investment Income NetInvestmentIncome	164949000	USD
	us-gaap	Net Investment Income NetInvestmentIncome	141227000	USD
CY2019Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	-2183000	USD
CY2018Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	-4787000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	15295000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	-16988000	USD
CY2019Q3	sigi	Total Investment Revenues TotalInvestmentRevenues	53643000	USD
CY2018Q3	sigi	Total Investment Revenues TotalInvestmentRevenues	47656000	USD
	sigi	Total Investment Revenues TotalInvestmentRevenues	180244000	USD
	sigi	Total Investment Revenues TotalInvestmentRevenues	124239000	USD
CY2019Q3	us-gaap	Revenues Revenues	710425000	USD
CY2018Q3	us-gaap	Revenues Revenues	664471000	USD
	us-gaap	Revenues Revenues	2117591000	USD
CY2019Q3	us-gaap	Net Investment Income NetInvestmentIncome	55826000	USD
CY2018Q3	us-gaap	Net Investment Income NetInvestmentIncome	52443000	USD
	us-gaap	Net Investment Income NetInvestmentIncome	164949000	USD
	us-gaap	Net Investment Income NetInvestmentIncome	141227000	USD
	us-gaap	Revenues Revenues	1943076000	USD
CY2019Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	-2183000	USD
CY2018Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	-4787000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	15295000	USD
	us-gaap	Gain Loss On Investments GainLossOnInvestments	-16988000	USD
CY2019Q3	sigi	Total Investment Revenues TotalInvestmentRevenues	53643000	USD
CY2018Q3	sigi	Total Investment Revenues TotalInvestmentRevenues	47656000	USD
	sigi	Total Investment Revenues TotalInvestmentRevenues	180244000	USD
	sigi	Total Investment Revenues TotalInvestmentRevenues	124239000	USD
CY2019Q3	sigi	Taxoninvestmentincome Taxoninvestmentincome	10884000	USD
CY2018Q3	sigi	Taxoninvestmentincome Taxoninvestmentincome	8562000	USD
	sigi	Taxoninvestmentincome Taxoninvestmentincome	34733000	USD
	sigi	Taxoninvestmentincome Taxoninvestmentincome	21405000	USD
CY2019Q3	sigi	Total Investment Income After Federal Income Tax TotalInvestmentIncomeAfterFederalIncomeTax	42759000	USD
CY2018Q3	sigi	Total Investment Income After Federal Income Tax TotalInvestmentIncomeAfterFederalIncomeTax	39094000	USD
	sigi	Total Investment Income After Federal Income Tax TotalInvestmentIncomeAfterFederalIncomeTax	145511000	USD
	sigi	Total Investment Income After Federal Income Tax TotalInvestmentIncomeAfterFederalIncomeTax	102834000	USD
CY2019Q3	sigi	Total Investment Revenues TotalInvestmentRevenues	53643000	USD
CY2018Q3	sigi	Total Investment Revenues TotalInvestmentRevenues	47656000	USD
	sigi	Total Investment Revenues TotalInvestmentRevenues	180244000	USD
	sigi	Total Investment Revenues TotalInvestmentRevenues	124239000	USD
CY2019Q3	us-gaap	Interest Expense Debt InterestExpenseDebt	7397000	USD
CY2018Q3	us-gaap	Interest Expense Debt InterestExpenseDebt	6073000	USD
	us-gaap	Interest Expense Debt InterestExpenseDebt	26289000	USD
	us-gaap	Interest Expense Debt InterestExpenseDebt	18350000	USD
CY2019Q3	us-gaap	Other General Expense OtherGeneralExpense	6369000	USD
CY2018Q3	us-gaap	Other General Expense OtherGeneralExpense	7450000	USD
	us-gaap	Other General Expense OtherGeneralExpense	28345000	USD
	us-gaap	Other General Expense OtherGeneralExpense	22065000	USD
CY2019Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	71178000	USD
CY2018Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	67130000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	235097000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	159586000	USD
CY2019Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	71178000	USD
CY2019Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	15028000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	56150000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	34392000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	7224000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	27168000	USD
CY2019Q3	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Before Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleBeforeTax	3000	USD
CY2019Q3	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleTax	1000	USD
CY2019Q3	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	2000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-2821000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	-592000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-2229000	USD
CY2019Q3	sigi	Total Unrealized Gains Losses On Investment Securities Gross TotalUnrealizedGainsLossesOnInvestmentSecuritiesGross	37210000	USD
CY2019Q3	sigi	Total Unrealized Gains Losses On Investment Securities Tax TotalUnrealizedGainsLossesOnInvestmentSecuritiesTax	7815000	USD
CY2019Q3	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	-29395000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-665000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-140000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-525000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-665000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-140000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-525000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	37875000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	7955000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	29920000	USD
CY2018Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11695000	USD
CY2019Q3	sigi	Comprehensive Income Loss Before Tax ComprehensiveIncomeLossBeforeTax	109053000	USD
CY2019Q3	sigi	Comprehensive Income Loss Tax ComprehensiveIncomeLossTax	22983000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	86070000	USD
CY2018Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	67130000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	55435000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-21565000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-4529000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-17036000	USD
CY2018Q3	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Before Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleBeforeTax	8000	USD
CY2018Q3	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleTax	2000	USD
CY2018Q3	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	6000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-10839000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	-2276000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-8563000	USD
CY2018Q3	sigi	Total Unrealized Gains Losses On Investment Securities Gross TotalUnrealizedGainsLossesOnInvestmentSecuritiesGross	-10734000	USD
CY2018Q3	sigi	Total Unrealized Gains Losses On Investment Securities Tax TotalUnrealizedGainsLossesOnInvestmentSecuritiesTax	-2255000	USD
CY2018Q3	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	8479000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-532000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-112000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-420000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-532000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-112000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-420000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-10202000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-2143000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-8059000	USD
CY2018Q3	sigi	Comprehensive Income Loss Before Tax ComprehensiveIncomeLossBeforeTax	56928000	USD
CY2018Q3	sigi	Comprehensive Income Loss Tax ComprehensiveIncomeLossTax	9552000	USD
CY2018Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	47376000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	235097000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	45333000	USD
	us-gaap	Net Income Loss NetIncomeLoss	189764000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	220864000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	46381000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	174483000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Before Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleBeforeTax	33000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleTax	7000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	26000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-444000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	-93000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-351000	USD
	sigi	Total Unrealized Gains Losses On Investment Securities Gross TotalUnrealizedGainsLossesOnInvestmentSecuritiesGross	221275000	USD
	sigi	Total Unrealized Gains Losses On Investment Securities Tax TotalUnrealizedGainsLossesOnInvestmentSecuritiesTax	46467000	USD
	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	-174808000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-1993000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-419000	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	-1574000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-1993000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-419000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1574000	USD
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	223268000	USD
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	46886000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	176382000	USD
	sigi	Comprehensive Income Loss Before Tax ComprehensiveIncomeLossBeforeTax	458365000	USD
	sigi	Comprehensive Income Loss Tax ComprehensiveIncomeLossTax	92219000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	366146000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	159586000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	26407000	USD
	us-gaap	Net Income Loss NetIncomeLoss	133179000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-130873000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-27484000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-103389000	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Before Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleBeforeTax	28000	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	22000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-18258000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	-3834000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-14424000	USD
	sigi	Total Unrealized Gains Losses On Investment Securities Gross TotalUnrealizedGainsLossesOnInvestmentSecuritiesGross	-112643000	USD
	sigi	Total Unrealized Gains Losses On Investment Securities Tax TotalUnrealizedGainsLossesOnInvestmentSecuritiesTax	-23656000	USD
	sigi	Total Unrealized Gains Losseson Investment Securities TotalUnrealizedGainsLossesonInvestmentSecurities	88987000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-1595000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-335000	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	-1260000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-1595000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-335000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1260000	USD
	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-111048000	USD
	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-23321000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-87727000	USD
	sigi	Comprehensive Income Loss Before Tax ComprehensiveIncomeLossBeforeTax	48538000	USD
	sigi	Comprehensive Income Loss Tax ComprehensiveIncomeLossTax	3086000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	45452000	USD
	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	0	USD
	sigi	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Non Credit Other Than Temporary Impaired Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForNonCreditOtherThanTemporaryImpairedSecuritiesNetOfTax	0	USD
	sigi	Amortization Of Net Unrealized Gains Losses On Held To Maturity Transferred From Available For Sale Netof Tax AmortizationOfNetUnrealizedGainsLossesOnHeldToMaturityTransferredFromAvailableForSaleNetofTax	26000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-351000	USD
CY2019Q3	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	217000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-1574000	USD
CY2019Q1	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	20700000	USD
CY2019Q1	us-gaap	Operating Lease Liability OperatingLeaseLiability	21000000.0	USD
CY2019Q1	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	900000	USD
CY2019Q3	us-gaap	Operating Lease Expense OperatingLeaseExpense	2234000	USD
	us-gaap	Operating Lease Expense OperatingLeaseExpense	6631000	USD
	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	816000	USD
CY2019Q3	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	5000	USD
	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	12000	USD
CY2019Q3	sigi	Finance Lease Expense FinanceLeaseExpense	222000	USD
	sigi	Finance Lease Expense FinanceLeaseExpense	828000	USD
CY2019Q3	us-gaap	Variable Lease Cost VariableLeaseCost	-548000	USD
	us-gaap	Variable Lease Cost VariableLeaseCost	120000	USD
CY2019Q3	us-gaap	Short Term Lease Cost ShortTermLeaseCost	502000	USD
	us-gaap	Short Term Lease Cost ShortTermLeaseCost	1677000	USD
CY2019Q3	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P6Y
CY2019Q3	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P2Y
CY2019Q3	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.034
CY2019Q3	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.020
CY2019Q3	sigi	Total Leases Due Remainderofthe Fiscal Year TotalLeasesDueRemainderoftheFiscalYear	2242000	USD
CY2019Q3	us-gaap	Finance Lease Liability Payments Due Next Twelve Months FinanceLeaseLiabilityPaymentsDueNextTwelveMonths	451000	USD
CY2019Q3	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	28348000	USD
CY2019Q3	us-gaap	Operating Lease Liability OperatingLeaseLiability	29218000	USD
CY2019Q3	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	899000	USD
CY2019Q3	us-gaap	Finance Lease Liability FinanceLeaseLiability	904000	USD
CY2019Q3	us-gaap	Finance Lease Liability Payments Remainder Of Fiscal Year FinanceLeaseLiabilityPaymentsRemainderOfFiscalYear	171000	USD
CY2019Q3	us-gaap	Lessee Operating Lease Liability Payments Remainder Of Fiscal Year LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear	2071000	USD
CY2019Q3	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	8164000	USD
CY2019Q3	sigi	Total Leases Due Next12 Months TotalLeasesDueNext12Months	8615000	USD
CY2019Q3	us-gaap	Finance Lease Liability Payments Due Year Two FinanceLeaseLiabilityPaymentsDueYearTwo	248000	USD
CY2019Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	6033000	USD
CY2019Q3	sigi	Total Leases Due In Two Years TotalLeasesDueInTwoYears	6281000	USD
CY2019Q3	us-gaap	Finance Lease Liability Payments Due Year Three FinanceLeaseLiabilityPaymentsDueYearThree	54000	USD
CY2019Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	4443000	USD
CY2019Q3	sigi	Total Leases Due In Three Years TotalLeasesDueInThreeYears	4497000	USD
CY2019Q3	us-gaap	Finance Lease Liability Payments Due Year Four FinanceLeaseLiabilityPaymentsDueYearFour	0	USD
CY2019Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	3232000	USD
CY2019Q3	sigi	Total Leases Due In Four Years TotalLeasesDueInFourYears	3232000	USD
CY2019Q3	us-gaap	Finance Lease Liability Payments Due Year Five FinanceLeaseLiabilityPaymentsDueYearFive	0	USD
CY2019Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	11446000	USD
CY2019Q3	sigi	Total Leases Due Thereafter TotalLeasesDueThereafter	11446000	USD
CY2019Q3	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	924000	USD
CY2019Q3	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	35389000	USD
CY2019Q3	sigi	Total Minimum Payment Required TotalMinimumPaymentRequired	36313000	USD
CY2019Q3	us-gaap	Finance Lease Liability Undiscounted Excess Amount FinanceLeaseLiabilityUndiscountedExcessAmount	20000	USD
CY2019Q3	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	3230000	USD
CY2019Q3	sigi	Total Imputed Interest TotalImputedInterest	3250000	USD
CY2019Q3	sigi	Finance Lease Liability Not Yet Commenced FinanceLeaseLiabilityNotYetCommenced	0	USD
CY2019Q3	sigi	Operating Lease Liability Not Yet Commenced OperatingLeaseLiabilityNotYetCommenced	2941000	USD
CY2019Q3	sigi	Total Lease Liability Not Yet Commenced TotalLeaseLiabilityNotYetCommenced	2941000	USD
CY2019Q3	us-gaap	Finance Lease Liability FinanceLeaseLiability	904000	USD
CY2019Q3	us-gaap	Operating Lease Liability OperatingLeaseLiability	29218000	USD
CY2019Q3	sigi	Total Lease Liability TotalLeaseLiability	30122000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due Current CapitalLeasesFutureMinimumPaymentsDueCurrent	728000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	7762000	USD
CY2018Q4	sigi	Total Leases Due Next12 Months TotalLeasesDueNext12Months	8490000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due In Two Years CapitalLeasesFutureMinimumPaymentsDueInTwoYears	141000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	7355000	USD
CY2018Q4	sigi	Total Leases Due In Two Years TotalLeasesDueInTwoYears	7496000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due In Three Years CapitalLeasesFutureMinimumPaymentsDueInThreeYears	22000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	5083000	USD
CY2018Q4	sigi	Total Leases Due In Three Years TotalLeasesDueInThreeYears	5105000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due In Four Years CapitalLeasesFutureMinimumPaymentsDueInFourYears	0	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	3641000	USD
CY2018Q4	sigi	Total Leases Due In Four Years TotalLeasesDueInFourYears	3641000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due In Five Years CapitalLeasesFutureMinimumPaymentsDueInFiveYears	0	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	2900000	USD
CY2018Q4	sigi	Total Leases Due In Five Years TotalLeasesDueInFiveYears	2900000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due Thereafter CapitalLeasesFutureMinimumPaymentsDueThereafter	0	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	9698000	USD
CY2018Q4	sigi	Total Leases Due Thereafter TotalLeasesDueThereafter	9698000	USD
CY2018Q4	us-gaap	Capital Leases Future Minimum Payments Due CapitalLeasesFutureMinimumPaymentsDue	891000	USD
CY2018Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	36439000	USD
CY2018Q4	sigi	Total Minimum Payment Required TotalMinimumPaymentRequired	37330000	USD

Files In Submission

Name	View Source	Status
0000230557-19-000028-index-headers.html	Edgar Link	pending
0000230557-19-000028-index.html	Edgar Link	pending
0000230557-19-000028.txt	Edgar Link	pending
0000230557-19-000028-xbrl.zip	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
MetaLinks.json	Edgar Link	pending
R1.htm	Edgar Link	pending
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R8.htm	Edgar Link	pending
R9.htm	Edgar Link	pending
report.css	Edgar Link	pending
Show.js	Edgar Link	pending
sigi-20190930.xsd	Edgar Link	pending
sigi-20190930_cal.xml	Edgar Link	unprocessable
sigi-20190930_def.xml	Edgar Link	unprocessable
sigi-20190930_lab.xml	Edgar Link	unprocessable
sigi-20190930_pre.xml	Edgar Link	unprocessable
sigi-9302019x10q.htm	Edgar Link	pending
sigi-9302019x10q_htm.xml	Edgar Link	completed
sigi-ex119302019xq3.htm	Edgar Link	pending
sigi-ex3119302019xq3.htm	Edgar Link	pending
sigi-ex3129302019xq3.htm	Edgar Link	pending
sigi-ex3219302019xq3.htm	Edgar Link	pending
sigi-ex3229302019xq3.htm	Edgar Link	pending

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$SIGI
Selective Insurance Group Inc Stock $sigi

2019 Q4 Form 10-Q Financial Statement

#000023055719000028 Filed on October 31, 2019

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$SIGI Selective Insurance Group Inc Stock $sigi

2019 Q4 Form 10-Q Financial Statement

#000023055719000028 Filed on October 31, 2019

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$SIGI
Selective Insurance Group Inc Stock $sigi