Loans - Secured Loans by Property Type (Details) $ in Thousands		1 Months Ended	9 Months Ended	12 Months Ended
		Jun. 30, 2020 MortgageLoan	Sep. 30, 2021 USD ($) MortgageLoan	Dec. 31, 2020 USD ($) MortgageLoan	Jun. 30, 2021 USD ($)
Loans (Details) - Secured Loans by Property Type [Line Items]
Number of secured loans | MortgageLoan		2	33	33
Secured loans, principal | $			$ 70,227	$ 74,080	$ 72,548
Loans - percent			100.00%	100.00%
Single Family [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Number of secured loans | MortgageLoan	[1]		16	19
Secured loans, principal | $	[1]		$ 13,492	$ 16,598
Loans - percent	[1]		19.00%	22.00%
Multi-family [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Number of secured loans | MortgageLoan			2	1
Secured loans, principal | $			$ 8,200	$ 6,300
Loans - percent			12.00%	9.00%
Commercial [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Number of secured loans | MortgageLoan			15	12
Secured loans, principal | $			$ 48,535	$ 49,682
Loans - percent			69.00%	67.00%
Land [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Number of secured loans | MortgageLoan				1
Secured loans, principal | $				$ 1,500
Loans - percent				2.00%

[1] Single family property type at September 30, 2021, consists of 4 loans with aggregate principal of approximately $1,793,000 that are owner occupied and 12 loans with aggregate principal of approximately $11,699,000 that are non-owner occupied. At December 31, 2020, single family property type consisted of 8 loans with aggregate principal of $3,344,000 that are owner occupied and 11 loans with aggregate principal of $13,254,000 that are non-owner occupied. Single family includes 1-4 unit residential buildings, condominium units, townhouses and condominium complexes.