Investments in Apartment/Mixed Use Joint Ventures as of December 31, 2021 (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Mar. 31, 2021
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	$ 533,996	$ 472,317
Cash and cash equivalents	9,441	2,987
Unrealized rents & receivables	6,964	4,342
Deferred costs	2,022	898
Total Assets	676,990	678,190
Secured notes payable	298,104	222,635
Other liabilities	15,750	28,253
Capital – Third Parties	398,234	396,423
Total Liabilities and Capital	676,990	678,190
Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	552,423	480,544
Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	138,998	139,981
Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital – Third Parties	99,571	89,675
Real Estate Partnership Total Liabilities And Capital [Member]
Schedule of Equity Method Investments [Line Items]
Total Liabilities and Capital	552,423	480,544
Riverfront Holdings I I L L C [Member]
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	0	0
Cash and cash equivalents	0	0
Unrealized rents & receivables	0	0
Deferred costs	0	0
Total Assets			$ 150,082
Secured notes payable	0	0
Other liabilities	0	0
Capital - FRP			18,513
Capital – Third Parties			44,200
Total Liabilities and Capital			$ 150,082
Riverfront Holdings I I L L C [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	0	0
Riverfront Holdings I I L L C [Member] | Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	0	0
Riverfront Holdings I I L L C [Member] | Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital – Third Parties	0	0
Riverfront Holdings I I L L C [Member] | Real Estate Partnership Total Liabilities And Capital [Member]
Schedule of Equity Method Investments [Line Items]
Total Liabilities and Capital	0	0
Bryant Street Partnerships [Member]
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	194,062	199,730
Cash and cash equivalents	1,719	1,123
Unrealized rents & receivables	5,231	2,925
Deferred costs	560	304
Secured notes payable	128,980	119,201
Other liabilities	3,394	9,066
Bryant Street Partnerships [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	201,572	204,082
Bryant Street Partnerships [Member] | Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	53,275	57,555
Bryant Street Partnerships [Member] | Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital – Third Parties	15,923	18,260
Bryant Street Partnerships [Member] | Real Estate Partnership Total Liabilities And Capital [Member]
Schedule of Equity Method Investments [Line Items]
Total Liabilities and Capital	201,572	204,082
D S T Hickory Creek [Member]
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	42,740	43,840
Cash and cash equivalents	391	827
Unrealized rents & receivables	1,230	1,044
Deferred costs	285	337
Secured notes payable	29,371	29,337
Other liabilities	155	115
D S T Hickory Creek [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	44,646	46,048
D S T Hickory Creek [Member] | Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	4,029	4,423
D S T Hickory Creek [Member] | Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital – Third Parties	11,091	12,173
D S T Hickory Creek [Member] | Real Estate Partnership Total Liabilities And Capital [Member]
Schedule of Equity Method Investments [Line Items]
Total Liabilities and Capital	44,646	46,048
Half St Owner L L C [Member]
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	128,437	93,504
Cash and cash equivalents	438	428
Unrealized rents & receivables	52	0
Deferred costs	213	0
Secured notes payable	60,153	18,404
Other liabilities	8,417	14,470
Half St Owner L L C [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	129,140	93,932
Half St Owner L L C [Member] | Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	37,179	37,478
Half St Owner L L C [Member] | Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital – Third Parties	23,391	23,580
Half St Owner L L C [Member] | Real Estate Partnership Total Liabilities And Capital [Member]
Schedule of Equity Method Investments [Line Items]
Total Liabilities and Capital	129,140	93,932
Greenville Woodfield Partnerships [Member]
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	95,420	87,421
Cash and cash equivalents	642	279
Unrealized rents & receivables	18	5
Deferred costs	540	26
Secured notes payable	63,600	44,309
Other liabilities	3,557	4,462
Greenville Woodfield Partnerships [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	96,620	87,731
Greenville Woodfield Partnerships [Member] | Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	11,439	15,584
Greenville Woodfield Partnerships [Member] | Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital – Third Parties	18,024	23,376
Greenville Woodfield Partnerships [Member] | Real Estate Partnership Total Liabilities And Capital [Member]
Schedule of Equity Method Investments [Line Items]
Total Liabilities and Capital	96,620	87,731
Apartment Mixed Use [Member]
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	460,659	424,495
Cash and cash equivalents	3,190	2,657
Unrealized rents & receivables	6,531	3,974
Deferred costs	1,598	667
Secured notes payable	282,104	211,251
Other liabilities	15,523	28,113
Apartment Mixed Use [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	471,978	431,793
Apartment Mixed Use [Member] | Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	105,922	115,040
Apartment Mixed Use [Member] | Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital – Third Parties	68,429	77,389
Apartment Mixed Use [Member] | Real Estate Partnership Total Liabilities And Capital [Member]
Schedule of Equity Method Investments [Line Items]
Total Liabilities and Capital	$ 471,978	$ 431,793