Investments in unconsolidated joint ventures (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	May 04, 2018
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		70.41%
Total investments	$ 143,005,000		$ 145,443,000
Total assets of the partnership	674,867,000		678,190,000
Partnership profit (loss)	404,000	$ 40,875,000
Share of profit (loss) of the partnership	(1,604,000)	(1,635,000)
Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	493,635,000		480,544,000
Partnership profit (loss)	(2,803,000)		(8,573,000)
Real Estate Partnership Net Income Loss [Member]
Schedule of Equity Method Investments [Line Items]
Share of profit (loss) of the partnership	$ (1,604,000)		$ (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	$ 7,475,000		$ 7,488,000
Partnership profit (loss)	(23,000)		(82,000)
Share of profit (loss) of the partnership	(12,000)		(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	$ 14,319,000		$ 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	$ 5,494,000		$ 5,530,000
Partnership profit (loss)	(72,000)		(230,000)
Share of profit (loss) of the partnership	(36,000)		(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	$ 22,239,000		$ 22,470,000
Bryant Street Partnerships [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	61.36%		61.36%
Total investments	$ 59,420,000		$ 59,558,000
Partnership profit (loss)	(2,251,000)		(6,084,000)
Share of profit (loss) of the partnership	(1,509,000)		(4,954,000)
Preferred interest	118,000	234,000
Guarantee liability amortization		118,000
Bryant Street Partnerships [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	203,870,000		204,082,000
Aberdeen Station [Member]
Schedule of Equity Method Investments [Line Items]
Total investments	638,000		514,000
Partnership profit (loss)	0		0
Share of profit (loss) of the partnership	0		0
Aberdeen Station [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	$ 638,000		$ 514,000
D S T Hickory Creek [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	26.65%		26.65%
Total investments	$ 6,000,000		$ 6,000,000
Partnership profit (loss)	(127,000)		(481,000)
Share of profit (loss) of the partnership	85,000		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	45,679,000		46,048,000
Amber Ridge Loan [Member]
Schedule of Equity Method Investments [Line Items]
Total investments	8,912,000		11,466,000
Partnership profit (loss)	0		0
Amber Ridge Loan [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	$ 8,912,000		$ 11,466,000
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	$ 38,935,000		$ 38,693,000
Partnership profit (loss)	0		12,000
Share of profit (loss) of the partnership	0		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	$ 107,219,000		$ 93,932,000
Greenville Woodfield Partnerships [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	40.00%		40.00%
Total investments	$ 16,131,000		$ 16,194,000
Partnership profit (loss)	(330,000)		(948,000)
Share of profit (loss) of the partnership	(132,000)		(379,000)
Greenville Woodfield Partnerships [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total assets of the partnership	90,759,000		87,731,000
Riverfront Holdings I I L L C [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage				80.00%
Total investments			0
Total assets of the partnership		$ 150,082,000
Partnership profit (loss)			(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		$ 0