Investments - Allowance For Credit Losses (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
Balance, beginning of the period	$ 1,203	$ 0
Additions to the allowance for credit losses on securities not previously recorded		(2,927)
Decrease to the allowance for losses	100	1,824
Decreases to the allowance for credit losses for securities sold	(18)	(18)
Balance, end of the period	1,085	1,085
Corporate bonds
Debt Securities, Available-for-sale, Allowance for Credit Loss
Balance, beginning of the period	1,203	0
Additions to the allowance for credit losses on securities not previously recorded		(2,927)
Decrease to the allowance for losses	100	1,824
Decreases to the allowance for credit losses for securities sold	(18)	(18)
Balance, end of the period	$ 1,085	$ 1,085