Schedule IV - Mortgage Loans on Real Estate - Mortgage Loans on Real Estate (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Carrying amount		$ 73,102	$ 32,246	$ 7,829	$ 14,448
Mortgage Loans [Member]
Face amount		75,911
Carrying amount	[1]	73,102
Principal Amount of Loans Subject to Delinquent Principal or Interest		500
Allowance for Credit losses:	[1]	$ (1,300)
Retail Site [Member] | Mesa, AZ [Member] | Borrower A [Member] | Mortgage Loans [Member]
Interest rate		12.00%
Face amount		$ 500
Carrying amount	[1]	500
Principal Amount of Loans Subject to Delinquent Principal or Interest		$ 500
Retail Site [Member] | Pompano, FL [Member] | Borrower C [Member] | Mortgage Loans [Member]
Interest rate		12.00%
Face amount		$ 25,000
Carrying amount	[1]	$ 25,000
Retail Site [Member] | Jacksonville, FL [Member] | Borrower D [Member] | Mortgage Loans [Member]
Interest rate		10.00%
Face amount		$ 15,000
Carrying amount		$ 15,000
Retail Site [Member] | San Antonio, Texas [Member] | Borrower E [Member] | Mortgage Loans [Member]
Interest rate		12.50%
Face amount		$ 21,500
Carrying amount		$ 21,500
Retail Site [Member] | Las Vegas, NV [Member] | Borrower F [Member] | Mortgage Loans [Member]
Interest rate		12.00%
Face amount		$ 3,075
Carrying amount	[1]	$ 3,075
Retail Site [Member] | Las Vegas, NV [Member] | Borrower G [Member] | Mortgage Loans [Member]
Interest rate		7.00%
Face amount		$ 3,410
Carrying amount		$ 3,410
Nonretail [Member] | Borrower A [Member] | Other Financing Loans [Member]
Interest rate		5.00%
Face amount		$ 175
Carrying amount	[1]	$ 105
Nonretail [Member] | Borrower C [Member] | Other Financing Loans [Member]
Interest rate		8.00%
Face amount		$ 5,000
Carrying amount		$ 5,000
Nonretail [Member] | Borrower B [Member] | Other Financing Loans [Member]
Interest rate		7.00%
Face amount		$ 397
Carrying amount	[1]	$ 375
Nonretail [Member] | Commack, NY [Member] | Borrower A [Member] | Mortgage Loans [Member]
Interest rate		7.41%
Face amount		$ 1,354
Carrying amount	[1]	$ 211
Nonretail [Member] | Melbourne, FL [Member] | Borrower B [Member] | Mortgage Loans [Member]
Interest rate		6.88%
Face amount		$ 500
Carrying amount	[1]	$ 226

[1] The aggregate cost for Federal income tax purposes was approximately $32.2 million as of December 31, 2020.