Investments in Fixed Maturity Securities (HTM Allowance for Credit Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ 730	$ 107	$ 798	$ 0
Cumulative effect adjustment resulting from changes in accounting principles	453	948	453	948
Provision for expected credit losses	(277)	841	(345)	879
Allowance for expected credit losses, end of period	$ 453	$ 948	453	948
Cumulative effect adjustment resulting from changes in accounting principles
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period			$ 0	$ 69
Cumulative effect adjustment resulting from changes in accounting principles