Investments in Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Jul. 31, 2019	Dec. 24, 2018	May 04, 2018	Apr. 26, 2016	Oct. 04, 2006
Total Investment	$ 161,924		$ 160,452
Total Assets of the Partnership	382,721		334,742
Profit (Loss) of the Partnership	(244)		(1,201)
Company's share of Net Loss of the Partnership	(642)	$ (264)	(1,954)
Investments in real estate, net	320,996		287,106
Cash and cash equivalents	59,811		45,909
Deferred costs	898		821
Unrealized rents & receivable	1,016		906
Secured notes payable	107,304		81,573
Other liabilities	26,621		27,524
Capital - FRP	171,215		170,832
Capital - Third parties	77,581		54,813
Total liabilities and capital	$ 382,721		$ 334,742
Brooksville Quarry, LLC
Ownership percent	50.00%		50.00%					50.00%
Total Investment	$ 7,486		$ 7,499
Total Assets of the Partnership	14,335		14,316
Profit (Loss) of the Partnership	(24)		(84)
Company's share of Net Loss of the Partnership	(12)		(42)
Investments in real estate, net	14,291		14,293
Cash and cash equivalents	41		18
Deferred costs	3		5
Unrealized rents & receivable	0		0
Secured notes payable	0		0
Other liabilities	47		2
Capital - FRP	7,486		7,500
Capital - Third parties	6,802		6,814
Total liabilities and capital	$ 14,335		$ 14,316
BC FRP Realty, LLC
Ownership percent	50.00%		50.00%				50.00%
Total Investment	$ 5,295		$ 5,391
Total Assets of the Partnership	22,818		22,969
Profit (Loss) of the Partnership	(124)		(1,114)
Company's share of Net Loss of the Partnership	(62)		(591)
Investments in real estate, net	22,311		22,423
Cash and cash equivalents	20		15
Deferred costs	262		311
Unrealized rents & receivable	225		220
Secured notes payable	12,161		12,103
Other liabilities	117		196
Capital - FRP	5,270		5,335
Capital - Third parties	5,270		5,335
Total liabilities and capital	$ 22,818		$ 22,969
RiverFront Holdings II, LLC
Ownership percent	80.00%		80.00%			80.00%
Total Investment	$ 26,092		$ 25,975
Total Assets of the Partnership	100,315		88,235
Profit (Loss) of the Partnership	(242)		(95)
Company's share of Net Loss of the Partnership	(391)		(871)
Investments in real estate, net	99,680		87,521
Cash and cash equivalents	535		630
Deferred costs	24		2
Unrealized rents & receivable	76		82
Secured notes payable	50,503		38,564
Other liabilities	6,908		6,771
Capital - FRP	37,339		37,284
Capital - Third parties	5,565		5,616
Total liabilities and capital	$ 100,315		$ 88,235
Bryant Street Partnerships
Ownership percent	61.36%		61.36%		61.36%
Total Investment	$ 59,008		$ 58,353
Total Assets of the Partnership	110,925		96,477
Profit (Loss) of the Partnership	0		260
Company's share of Net Loss of the Partnership	(432)		(573)
Investments in real estate, net	110,573		95,903
Cash and cash equivalents	161		387
Deferred costs	14		29
Unrealized rents & receivable	177		158
Secured notes payable	15,383		1,660
Other liabilities	17,540		17,183
Capital - FRP	57,848		57,479
Capital - Third parties	20,154		20,155
Total liabilities and capital	110,925		96,477
Hyde Park
Total Investment	3,741		3,492
Total Assets of the Partnership	3,741		3,492
Profit (Loss) of the Partnership	0		0
Company's share of Net Loss of the Partnership	0		0
Investments in real estate, net	3,741		3,492
Cash and cash equivalents	0		0
Deferred costs	0		0
Unrealized rents & receivable	0		0
Secured notes payable	0		0
Other liabilities	0		0
Capital - FRP	3,741		3,492
Capital - Third parties	0		0
Total liabilities and capital	$ 3,741		$ 3,492
DST Hickory Creek
Ownership percent	26.65%		26.65%	26.65%
Total Investment	$ 6,000		$ 6,000
Total Assets of the Partnership	49,208		49,369
Profit (Loss) of the Partnership	(75)		(168)
Company's share of Net Loss of the Partnership	83		123
Investments in real estate, net	46,472		46,685
Cash and cash equivalents	1,741		1,764
Deferred costs	457		474
Unrealized rents & receivable	538		446
Secured notes payable	29,257		29,246
Other liabilities	335		120
Capital - FRP	5,228		6,000
Capital - Third parties	14,388		14,003
Total liabilities and capital	49,208		49,369
Amber Ridge
Total Investment	876		509
Total Assets of the Partnership	876		509
Profit (Loss) of the Partnership	0		0
Company's share of Net Loss of the Partnership	0		0
Investments in real estate, net	876		509
Cash and cash equivalents	0		0
Deferred costs	0		0
Unrealized rents & receivable	0		0
Secured notes payable	0		0
Other liabilities	0		0
Capital - FRP	876		509
Capital - Third parties	0		0
Total liabilities and capital	$ 876		$ 509
1800 Half Street
Ownership percent	59.73%		59.73%
Total Investment	$ 37,439		$ 37,314
Total Assets of the Partnership	39,818		40,161
Profit (Loss) of the Partnership	105		0
Company's share of Net Loss of the Partnership	105		0
Investments in real estate, net	17,844		14,391
Cash and cash equivalents	21,974		25,770
Deferred costs	0		0
Unrealized rents & receivable	0		0
Secured notes payable	0		0
Other liabilities	903		1,363
Capital - FRP	37,440		37,314
Capital - Third parties	1,475		1,484
Total liabilities and capital	$ 39,818		$ 40,161
Woodfield Partnerships
Ownership percent	40.00%		40.00%
Total Investment	$ 15,987		$ 15,919
Total Assets of the Partnership	40,685		19,214
Profit (Loss) of the Partnership	116		0
Company's share of Net Loss of the Partnership	67		0
Investments in real estate, net	5,208		1,889
Cash and cash equivalents	35,339		17,325
Deferred costs	138		0
Unrealized rents & receivable	0		0
Secured notes payable	0		0
Other liabilities	771		1,889
Capital - FRP	15,987		15,919
Capital - Third parties	23,927		1,406
Total liabilities and capital	40,685		19,214
Apartment Mixed Use Totals
Total Assets of the Partnership	340,951		293,456
Investments in real estate, net	279,777		246,389
Cash and cash equivalents	59,750		45,876
Deferred costs	633		505
Unrealized rents & receivable	791		686
Secured notes payable	95,143		69,470
Other liabilities	26,457		27,326
Capital - FRP	153,842		153,996
Capital - Third parties	65,509		42,664
Total liabilities and capital	$ 340,951		$ 293,456