Investments - Schedule of Changes in Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning Balance	$ 528,447	$ 705,193
Included in realized gains/losses	0	0
Included in other comprehensive income	828	(40,169)
Acquisitions	0	0
Sales	0	0
Amortization	1,143	1,124
Other	(13,277)	(20,640)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending Balance	$ 517,141	$ 645,508
Percentage of total	3.00%	3.00%
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Realized gains (losses)	Realized gains (losses)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Asset, Gain (Loss), Statement of Other Comprehensive Income or Comprehensive Income [Extensible Enumeration]	Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent
Asset- backed Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning Balance	$ 0	$ 0
Included in realized gains/losses	0	0
Included in other comprehensive income	0	0
Acquisitions	0	0
Sales	0	0
Amortization	0	0
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending Balance	$ 0	$ 0
Percentage of total	0.00%	0.00%
Collateralized debt obligations
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning Balance	$ 50,364	$ 63,505
Included in realized gains/losses	0	0
Included in other comprehensive income	(4,542)	(3,809)
Acquisitions	0	0
Sales	0	0
Amortization	1,141	1,123
Other	(1,461)	(1,281)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending Balance	$ 45,502	$ 59,538
Percentage of total	0.00%	0.00%
Corporates
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning Balance	$ 478,083	$ 641,688
Included in realized gains/losses	0	0
Included in other comprehensive income	5,370	(36,360)
Acquisitions	0	0
Sales	0	0
Amortization	2	1
Other	(11,816)	(19,359)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending Balance	$ 471,639	$ 585,970
Percentage of total	3.00%	3.00%

Fair value, measurement with unobservable inputs reconciliation, recurring basis, asset, amortization.

No definition available.

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- Definition

Other adjustments, including capitalized interest and foreign exchange.

+ References

No definition available.

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- Definition

Percent Of Available For Sale Securities At Fair Value By Valuation Level

+ References

No definition available.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

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- Definition

Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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-Section 50
-Paragraph 2
-Subparagraph (c)(1a)
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- Definition

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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-Publisher FASB
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-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

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- Definition

Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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- Definition

Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

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- Definition

Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

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- Definition

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

Indicates line item in statement in which net income is reported that includes gain (loss) from asset measured at fair value using unobservable input (level 3).

+ References

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Indicates line item in statement in which other comprehensive income (OCI) is reported that includes gain (loss) from asset measured at fair value using unobservable input (level 3).

+ References

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