Note 7 - Real Estate (Details Textual) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Real Estate Held-for-sale, Period Increase (Decrease)	$ 12,068,730	$ 3,984,605
Real Estate Held-for-sale	48,270,000	36,201,270	$ 33,016,665
Port Jefferson Professional Park [Member]
Real Estate Held-for-sale, Period Increase (Decrease)		$ (800,000)
Real Estate Held-for-sale	$ 48,270,000

Carrying amount as of the balance sheet date of investments in land and buildings held for sale, excluding real estate considered to be inventory of the entity.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(f))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Name:	us-gaap_RealEstateHeldforsale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant