Fair Value Measurement (Level 3 Assets and Liability) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 68,568	$ 19,234	$ 57,565	$ 11,958
Included in earnings, as a part of:
Included in other comprehensive income	(1,496)	93	(2,749)	(66)
Purchases	10,260	24,006	27,039	36,238
Sales	(2,199)	(6,075)	(3,339)	(6,396)
Transfers in	20,523	0	22,052	3,010
Transfers out	(11,093)	(9,128)	(16,116)	(16,602)
Ending balance	83,776	27,996	83,776	27,996
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	(787)	(135)	(723)	(135)
Net investment income
Included in earnings, as a part of:
Included in earnings	0	0	1	(1)
Net investment gains (losses)
Included in earnings, as a part of:
Included in earnings	(787)	(134)	(677)	(145)
Corporate Debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	53,325	7,769	47,129	3,265
Included in earnings, as a part of:
Included in other comprehensive income	(1,319)	13	(2,312)	33
Purchases	8,787	9,215	18,498	14,090
Sales	(2,007)	(160)	(3,026)	(177)
Transfers in	17,828	0	18,828	858
Transfers out	(2,402)	(1,772)	(4,905)	(3,005)
Ending balance	74,212	15,065	74,212	15,065
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	0	0	0	0
Corporate Debt \| Net investment income
Included in earnings, as a part of:
Included in earnings	0	0	0	1
Corporate Debt \| Net investment gains (losses)
Included in earnings, as a part of:
Included in earnings	0	0	0	0
Asset-backed Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	9,303	9,313	6,502	8,693
Included in earnings, as a part of:
Included in other comprehensive income	(177)	82	(437)	(97)
Purchases	1,473	8,003	7,058	15,360
Sales	(192)	(185)	(197)	(489)
Transfers in	570	0	570	0
Transfers out	(6,939)	(7,356)	(9,459)	(13,597)
Ending balance	4,038	9,857	4,038	9,857
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	0	0	0	0
Asset-backed Securities \| Net investment income
Included in earnings, as a part of:
Included in earnings	0	0	1	(2)
Asset-backed Securities \| Net investment gains (losses)
Included in earnings, as a part of:
Included in earnings	0	0	0	(11)
Equity Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	2,500	0	2,500	0
Included in earnings, as a part of:
Included in other comprehensive income	0	(2)	0	(2)
Purchases	0	6,583	0	6,583
Sales	0	(5,730)	0	(5,730)
Transfers in	2,125	0	2,125	0
Transfers out	0	0	0	0
Ending balance	4,625	852	4,625	852
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	0	0	0	0
Equity Investments \| Net investment income
Included in earnings, as a part of:
Included in earnings	0	0	0	0
Equity Investments \| Net investment gains (losses)
Included in earnings, as a part of:
Included in earnings	0	1	0	1
Other Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3,440	2,152	1,434	0
Included in earnings, as a part of:
Included in other comprehensive income	0	0	0	0
Purchases	0	205	1,483	205
Sales	0	0	(116)	0
Transfers in	0	0	529	2,152
Transfers out	(1,752)	0	(1,752)	0
Ending balance	901	2,222	901	2,222
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end	(787)	(135)	(723)	(135)
Other Investments \| Net investment income
Included in earnings, as a part of:
Included in earnings	0	0	0	0
Other Investments \| Net investment gains (losses)
Included in earnings, as a part of:
Included in earnings	$ (787)	$ (135)	$ (677)	$ (135)

Included in Earnings, as a part of.

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

+ 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 (d)
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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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).

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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.

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-Publisher FASB
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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.

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- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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- Definition

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

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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.

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