Investments in Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2016	Jun. 30, 2013	Oct. 04, 2006
Company's share of Net Loss of the Partnership	$ (12)	$ (771)
Revenue - Reimbursements	1,707	1,300
Total revenues	12,622	9,322
Operating expenses	2,043	1,001
Property taxes	1,473	1,062
Total cost of operations	9,764	5,918
Total operating profit	2,858	3,404
Interest expense	$ (1,243)	(248)
Brooksville Quarry, LLC
Ownership percent	50.00%		50.00%				50.00%
Total Investment	$ 7,503		$ 7,516
Total Assets of the Partnership	14,408		14,411
Net Loss of the Partnership	(24)		(80)
Company's share of Net Loss of the Partnership	$ (12)		$ (40)
BC FRP Realty, LLC
Ownership percent	50.00%		50.00%		50.00%
Total Investment	$ 5,919		$ 5,890
Total Assets of the Partnership	16,814		15,027
Net Loss of the Partnership	0		0
Company's share of Net Loss of the Partnership	0		$ 0
Riverfront Holdings I, LLC
Ownership percent			0.00%			77.14%
Total Investment			$ 0	$ 8,583
Total Assets of the Partnership			0
Net Loss of the Partnership			(2,019)
Company's share of Net Loss of the Partnership			(1,558)
Rental revenue		1,311
Revenue - Reimbursements		15
Total revenues		1,326
Depreciation and amortization		863
Operating expenses		475
Property taxes		219
Total cost of operations		1,557
Total operating profit		(231)
Interest expense		(756)
Net loss of the Partnership		$ (987)
Joint Ventures
Total Investment	13,422		13,406
Total Assets of the Partnership	31,222		29,438
Net Loss of the Partnership	(24)		(2,099)
Company's share of Net Loss of the Partnership	$ (12)		$ (1,598)