XML 110 R78.htm IDEA: XBRL DOCUMENT v3.24.0.1

Fair Value Measurements (Quantitative Disclosures of Financial Assets Measured and Recorded at Fair Value) (Details) - USD ($) $ in Thousands		Dec. 31, 2023	Dec. 31, 2022
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		$ 7,499,197	$ 6,612,107
Equity securities		187,155	162,000
Short-term investments		309,317	440,456
Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		7,499,197	6,612,107
Equity securities		187,155	162,000
Short-term investments		309,317	440,456
Total assets measured at fair value		7,995,669	7,214,563
U.S. Government and Government Agencies [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		205,035	189,239
U.S. Government and Government Agencies [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		205,035	189,239
Foreign Government [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		9,803	9,608
Foreign Government [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		9,803	9,608
Obligations of States and Political Subdivisions [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		585,965	918,018
Obligations of States and Political Subdivisions [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		585,965	918,018
Corporate Securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		2,711,239	2,335,025
Corporate Securities [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		2,711,239	2,335,025
Collateralized Loan Obligations and Other Asset-Backed Securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		1,834,827	1,485,973
Collateralized Loan Obligations and Other Asset-Backed Securities [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		1,834,827	1,485,973
Residential Mortgage Backed Securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		1,477,483	1,059,832
Residential Mortgage Backed Securities [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		1,477,483	1,059,832
Commercial Mortgage-backed Securities (CMBS) [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		674,845	614,412
Commercial Mortgage-backed Securities (CMBS) [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		674,845	614,412
Common Stock [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities	[1]	185,339	160,355
Preferred Stock [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities		1,816	1,645
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		34,056	109,240
Equity securities		22,398	57,491
Short-term investments		308,512	418,199
Total assets measured at fair value		364,966	584,930
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | U.S. Government and Government Agencies [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		34,056	109,240
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Foreign Government [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Corporate Securities [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Collateralized Loan Obligations and Other Asset-Backed Securities [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Commercial Mortgage-backed Securities (CMBS) [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		0	0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Common Stock [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities	[1]	20,582	55,846
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Preferred Stock [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities		1,816	1,645
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		6,914,306	6,154,509
Equity securities		0	0
Short-term investments		805	22,257
Total assets measured at fair value		6,915,111	6,176,766
Significant Other Observable Inputs (Level 2) [Member] | U.S. Government and Government Agencies [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		170,979	79,999
Significant Other Observable Inputs (Level 2) [Member] | Foreign Government [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		9,803	9,608
Significant Other Observable Inputs (Level 2) [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		578,131	911,357
Significant Other Observable Inputs (Level 2) [Member] | Corporate Securities [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		2,413,907	2,147,045
Significant Other Observable Inputs (Level 2) [Member] | Collateralized Loan Obligations and Other Asset-Backed Securities [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		1,589,514	1,332,631
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		1,477,483	1,059,832
Significant Other Observable Inputs (Level 2) [Member] | Commercial Mortgage-backed Securities (CMBS) [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		674,489	614,037
Significant Other Observable Inputs (Level 2) [Member] | Common Stock [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities	[1]	0	0
Significant Other Observable Inputs (Level 2) [Member] | Preferred Stock [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		550,835	348,358
Equity securities		854	897
Short-term investments		0	0
Total assets measured at fair value		551,689	349,255
Significant Unobservable Inputs (Level 3) [Member] | U.S. Government and Government Agencies [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Foreign Government [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		7,834	6,661
Significant Unobservable Inputs (Level 3) [Member] | Corporate Securities [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		297,332	187,980
Significant Unobservable Inputs (Level 3) [Member] | Collateralized Loan Obligations and Other Asset-Backed Securities [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		245,313	153,342
Significant Unobservable Inputs (Level 3) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Commercial Mortgage-backed Securities (CMBS) [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
AFS fixed income securities		356	375
Significant Unobservable Inputs (Level 3) [Member] | Common Stock [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities	[1]	854	897
Significant Unobservable Inputs (Level 3) [Member] | Preferred Stock [Member] | Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities		0	0
Fair Value Measured at Net Asset Value Per Share
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities		$ 163,900	$ 103,600
[1] Investments amounting to $163.9 million at December 31, 2023 and $103.6 million at December 31, 2022, were measured at fair value using the net asset value per share (or its practical expedient) and have not been classified in the fair value hierarchy. These investments are not redeemable and the timing of liquidations of the underlying assets is unknown at each reporting period. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to total assets measured at fair value.

X

- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481830/320-10-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483467/210-10-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482736/825-10-45-1A

+ Details

Name:	us-gaap_EquitySecuritiesFvNi
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

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

+ References

No definition available.

+ Details

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

X

- Definition

Amount of short-term investments classified as other.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1)(g))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(8))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.5)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

+ Details

Name:	us-gaap_OtherShortTermInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommonStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_NonredeemablePreferredStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: