Investments Investments (Rollforward of Allowance for Credit Losses) (Details) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Additions for credit losses not previously recorded	$ 31,371
Reduction for securities with credit losses due to intent to sell	(3,039)
Ending balance	28,332
Corporate Securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Additions for credit losses not previously recorded	28,332
Reduction for securities with credit losses due to intent to sell	0
Ending balance	28,332
Commercial Mortgage Backed Securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Additions for credit losses not previously recorded	2,491
Reduction for securities with credit losses due to intent to sell	(2,491)
Ending balance	0
Other Asset Backed Securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Additions for credit losses not previously recorded	548
Reduction for securities with credit losses due to intent to sell	(548)
Ending balance	$ 0