Investments in Joint Ventures as of March 31, 2022 (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	$ 483,279	$ 472,317
Cash and cash equivalents	2,914	2,987
Unrealized rents & receivables	6,496	4,342
Deferred costs	946	898
Total Assets	674,867	678,190
Secured notes payable	250,404	222,635
Other liabilities	17,899	28,253
Capital - Third Parties	396,442	396,423
Total Liabilities and Capital	674,867	678,190
Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	493,635	480,544
Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	136,577	139,981
Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital - Third Parties	88,755	89,675
Real Estate Partnership Total Liabilities And Capital [Member]
Schedule of Equity Method Investments [Line Items]
Total Liabilities and Capital	493,635	480,544
Brooksville Quarry L L C [Member]
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	14,280	14,281
Cash and cash equivalents	33	18
Unrealized rents & receivables	0	0
Deferred costs	6	2
Secured notes payable	0	0
Other liabilities	42	0
Brooksville Quarry L L C [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	14,319	14,301
Brooksville Quarry L L C [Member] | Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	7,475	7,488
Brooksville Quarry L L C [Member] | Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital - Third Parties	6,802	6,813
Brooksville Quarry L L C [Member] | Real Estate Partnership Total Liabilities And Capital [Member]
Schedule of Equity Method Investments [Line Items]
Total Liabilities and Capital	14,319	14,301
B C F R P Realty L L C [Member]
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	21,436	21,561
Cash and cash equivalents	164	312
Unrealized rents & receivables	447	368
Deferred costs	192	229
Secured notes payable	11,191	11,384
Other liabilities	162	140
B C F R P Realty L L C [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	22,239	22,470
B C F R P Realty L L C [Member] | Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	5,443	5,473
B C F R P Realty L L C [Member] | Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital - Third Parties	5,443	5,473
B C F R P Realty L L C [Member] | Real Estate Partnership Total Liabilities And Capital [Member]
Schedule of Equity Method Investments [Line Items]
Total Liabilities and Capital	22,239	22,470
Aberdeen Station [Member]
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	638	514
Cash and cash equivalents	0	0
Unrealized rents & receivables	0	0
Deferred costs	0	0
Secured notes payable	0	0
Other liabilities	0	0
Aberdeen Station [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	638	514
Aberdeen Station [Member] | Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	638	514
Aberdeen Station [Member] | Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital - Third Parties	0	0
Aberdeen Station [Member] | Real Estate Partnership Total Liabilities And Capital [Member]
Schedule of Equity Method Investments [Line Items]
Total Liabilities and Capital	638	514
Amber Ridge Loan [Member]
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	8,912	11,466
Cash and cash equivalents	0	0
Unrealized rents & receivables	0	0
Deferred costs	0	0
Secured notes payable	0	0
Other liabilities	0	0
Amber Ridge Loan [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	8,912	11,466
Amber Ridge Loan [Member] | Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	8,912	11,466
Amber Ridge Loan [Member] | Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital - Third Parties	0	0
Amber Ridge Loan [Member] | Real Estate Partnership Total Liabilities And Capital [Member]
Schedule of Equity Method Investments [Line Items]
Total Liabilities and Capital	8,912	11,466
Apartment Mixed Use [Member]
Schedule of Equity Method Investments [Line Items]
Investments in real estate, net	438,013	424,495
Cash and cash equivalents	2,717	2,657
Unrealized rents & receivables	6,049	3,974
Deferred costs	748	667
Secured notes payable	239,213	211,251
Other liabilities	17,695	28,113
Apartment Mixed Use [Member] | Real Estate Total Assets [Member]
Schedule of Equity Method Investments [Line Items]
Total Assets	447,527	431,793
Apartment Mixed Use [Member] | Real Estate Partnership F R P [Member]
Schedule of Equity Method Investments [Line Items]
Capital - FRP	114,109	115,040
Apartment Mixed Use [Member] | Real Estate Partnership Third Parties [Member]
Schedule of Equity Method Investments [Line Items]
Capital - Third Parties	76,510	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	$ 447,527	$ 431,793