Investment in Life Insurance Policies - Reconciliation of Gain (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Life Settlement Contracts, Fair Value Method, Gain (Loss) [Abstract]
Change in estimated probabilistic cash flows	$ 13,120	$ 14,723	$ 40,230	$ 47,923
Premiums and other annual fees	(19,267)	(18,235)	(56,388)	(53,060)
Change in life expectancy evaluation	0	0	2,337	0
Change in PMM	0	0	(16,386)	0
Face value of matured policies	43,217	39,803	104,662	105,194
Fair value of matured policies	(21,586)	(22,169)	(56,532)	(56,702)
Gain on life insurance policies, net	$ 15,484	$ 14,122	$ 17,923	$ 43,355