Investments Investments (Rollforward of Allowance for Credit Losses) (Details) (Details) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
		Sep. 30, 2020	Sep. 30, 2020
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Beginning balance	[1]	$ 50,186
Additions for credit losses not previously recorded		25,923	$ 82,335
Reduction for securities with credit losses due to intent to sell		(14,490)	(20,716)
Ending balance		61,619	61,619
Corporate Securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Beginning balance	[1]	46,749
Additions for credit losses not previously recorded		6,296	53,045
Reduction for securities with credit losses due to intent to sell		0	0
Ending balance		53,045	53,045
Commercial Mortgage Backed Securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Beginning balance	[1]	2,660
Additions for credit losses not previously recorded		19,183	27,521
Reduction for securities with credit losses due to intent to sell		(14,490)	(20,168)
Ending balance		7,353	7,353
Residential Mortgage Backed Securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Beginning balance	[1]	777
Additions for credit losses not previously recorded		444	1,221
Reduction for securities with credit losses due to intent to sell		0	0
Ending balance		1,221	1,221
Other Asset Backed Securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Beginning balance	[1]	0
Additions for credit losses not previously recorded		0	548
Reduction for securities with credit losses due to intent to sell		0	(548)
Ending balance		$ 0	$ 0

[1] (1) The allowance for credit loss associated with available for sale fixed maturity securities was applied prospectively upon adoption of authoritative guidance effective January 1, 2020. See Note 1 for further details.