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Investments (Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Net Investment Income [Line Items]
Net investment income earned	$ 70,222	$ 83,731	$ 142,824	$ 153,447
Investment Expense	(5,220)	(5,469)	(9,337)	(9,096)
Fixed Income Securities [Member]
Net Investment Income [Line Items]
Net investment income earned	62,144	52,608	116,069	105,431
Commercial Mortgage Loans [Member]
Net Investment Income [Line Items]
Net investment income earned	1,192	695	2,162	1,209
Equity Securities [Member]
Net Investment Income [Line Items]
Net investment income earned	2,639	2,982	5,057	5,470
Short-Term Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	407	55	508	140
Other Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	9,060	32,860	28,365	50,293
Alternative Investments [Member]
Net Investment Income [Line Items]
Net investment income earned	$ 9,300	$ 29,900	$ 28,400	$ 50,100

X

- Definition

Amount of expenses related to the generation of investment income.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
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-Section S99
-Paragraph 1
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Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Section S99
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