Investments in unconsolidated joint ventures (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Aug. 31, 2022
Schedule of Equity Method Investments [Line Items]
Total investments	$ 140,525,000	$ 145,443,000
Total assets of the partnership	701,084,000	678,190,000	$ 536,360,000
Profit (loss) of the partnership	4,047,000	40,094,000	11,722,000
Share of profit (loss) of the partnership	(5,721,000)	(5,754,000)	$ (5,690,000)
Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	510,640,000	480,544,000
Profit (loss) of the partnership	(3,437,000)	(8,573,000)
Real Estate Partnership Net Income Loss [Member]
Schedule of Equity Method Investments [Line Items]
Share of profit (loss) of the partnership	$ (5,721,000)	$ (5,754,000)
Brooksville Quarry L L C [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%	50.00%
Total investments	$ 7,522,000	$ 7,488,000
Profit (loss) of the partnership	(84,000)	(82,000)
Share of profit (loss) of the partnership	(42,000)	(41,000)
Brooksville Quarry L L C [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	$ 14,374,000	$ 14,301,000
B C F R P Realty L L C [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%	50.00%
Total investments	$ 5,453,000	$ 5,530,000
Profit (loss) of the partnership	(358,000)	(230,000)
Share of profit (loss) of the partnership	(175,000)	(115,000)
B C F R P Realty L L C [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	$ 21,825,000	$ 22,470,000
Buzzard Point Sponsor Partnership [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Total investments	$ 1,453,000
Profit (loss) of the partnership	0
Share of profit (loss) of the partnership	0
Buzzard Point Sponsor Partnership [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	$ 2,906,000
Bryant Street Partnerships [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	61.36%	61.36%
Total investments	$ 55,561,000	$ 59,558,000
Profit (loss) of the partnership	(10,339,000)	(6,084,000)
Share of profit (loss) of the partnership	(6,829,000)	(4,954,000)
Bryant Street Partnerships [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	199,774,000	$ 204,082,000
Lending Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Total investments	16,476,000
Profit (loss) of the partnership	0
Share of profit (loss) of the partnership	0
Lending Ventures [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	$ 5,577,000
D S T Hickory Creek [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	26.65%	26.65%
Total investments	$ 0	$ 6,000,000
Profit (loss) of the partnership	10,960,000	(481,000)
Share of profit (loss) of the partnership	3,164,000	343,000
D S T Hickory Creek [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	$ 0	$ 46,048,000
Estero Partnership [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	16.00%			16.00%
Total investments	$ 3,600,000			$ 3,600,000
Profit (loss) of the partnership	0
Estero Partnership [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	$ 38,505,000
Half St Owner L L C [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	61.37%	61.37%
Total investments	$ 38,471,000	$ 38,693,000
Profit (loss) of the partnership	(1,841,000)	12,000
Share of profit (loss) of the partnership	(1,129,000)	20,000
Half St Owner L L C [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	$ 131,128,000	$ 93,932,000
Greenville Partnerships [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	40.00%	40.00%
Total investments	$ 11,989,000	$ 16,194,000
Profit (loss) of the partnership	(1,775,000)	(948,000)
Share of profit (loss) of the partnership	(710,000)	(379,000)
Greenville Partnerships [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	$ 96,551,000	87,731,000
Riverfront Holdings I I L L C [Member]
Schedule of Equity Method Investments [Line Items]
Total investments		0
Profit (loss) of the partnership		(760,000)
Share of profit (loss) of the partnership		(628,000)
Riverfront Holdings I I L L C [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership		0
Aberdeen Station [Member]
Schedule of Equity Method Investments [Line Items]
Total investments		514,000
Profit (loss) of the partnership		0
Share of profit (loss) of the partnership		0
Aberdeen Station [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership		514,000
Amber Ridge Loan [Member]
Schedule of Equity Method Investments [Line Items]
Total investments		11,466,000
Profit (loss) of the partnership		0
Share of profit (loss) of the partnership		0
Amber Ridge Loan [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership		$ 11,466,000