SCHEDULE IV MORTGAGE LOANS ON REAL ESTATE - Number of commercial loan investments (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2017	Dec. 31, 2016
Mortgage Loans On Real Estate [Line Items]
Face Amount of Mortgages	$ 34,570,000
Carrying Amounts of Mortgages	34,625,173	$ 11,925,699	$ 23,960,467
Carpenter Hotel-400 Josephine Street, Austin, TX
Mortgage Loans On Real Estate [Line Items]
Face Amount of Mortgages	16,250,000
Carrying Amounts of Mortgages	$ 16,443,942
First Mortgage, 72-Acre Land Parcel, Orlando, FL
Mortgage Loans On Real Estate [Line Items]
Interest rate (as a percent)	12.00%
Face Amount of Mortgages	$ 8,000,000
Carrying Amounts of Mortgages	$ 7,927,869
Mortgage Note, 400 Josephine Street, Austin, TX
Mortgage Loans On Real Estate [Line Items]
Interest rate (as a percent)	11.50%
Face Amount of Mortgages	$ 8,250,000
Carrying Amounts of Mortgages	$ 8,207,964
LPGA Buyer Loan - Daytona Beach, FL
Mortgage Loans On Real Estate [Line Items]
Interest rate (as a percent)	7.50%
Face Amount of Mortgages	$ 2,070,000
Carrying Amounts of Mortgages	$ 2,045,398