Investments - Allowance for Credit Loss on Beneficial Interests (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning balance	$ (615)	$ (4,453)
Reclassification to/(from) non-credit discount from/(to) the allowance for changes in payment expectations	311	(953)
Credit loss expense on beneficial interests	(50)	(139)
Reversal of allowance for expected credit losses due to increases in the net present value of expected cash flows	354	15
Allowance for expected credit losses, ending balance	$ 0	$ (5,530)