Loans - Secured Loans Scheduled Maturities (Details) $ in Thousands	Sep. 30, 2021 USD ($) Loan	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($) Loan
Receivables [Abstract]
2021, Loan | Loan	2
2022, Loan | Loan	20
2023, Loan | Loan	4
2024, Loan | Loan	1
Thereafter, Loan | Loan	2
Total scheduled maturities, Loan | Loan	29
Matured at September 30, 2021, Loan | Loan	4
Total principal, secured loans, Loan | Loan	33		33
2021, Principal | $	$ 1,000
2022, Principal | $	54,628
2023, Principal | $	3,713
2024, Principal | $	590
Thereafter, Principal | $	1,312
Total scheduled maturities, Principal | $	61,243
Matured at September 30, 2021, Principal | $	8,984
Total principal, secured loans, Principal | $	$ 70,227	$ 72,548	$ 74,080
2020, Percent	1.00%
2022, Percent	78.00%
2023, Percent	5.00%
2024, Percent	1.00%
Thereafter, Percent	2.00%
Total scheduled maturities, Percent	87.00%
Matured at September 30, 2021, Percent	13.00%
Total principal, secured loans, Percent	100.00%