Note 4 - Investment in Affiliate - Equity Method Investments (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Investment in affiliate, balance		$ 11,673		$ 11,673		$ 12,072
Loss recorded in the Consolidated Statements of Operations		$ 26	$ (124)	$ (199)	$ (301)
HC Government Realty Trust, Inc [Member]
Ownership percentage		34.10%		34.10%		36.40%
Investment in affiliate, balance		$ 11,673		$ 11,673		$ 12,072
Loss recorded in the Consolidated Statements of Operations	[1]	$ (50)	(124)	$ (275)	(301)
HC Government Realty Trust, Inc [Member] | Series B Cumulative Convertible Preferred Stock [Member]
Ownership percentage	[2]	26.90%		26.90%		28.70%
Investment in affiliate, balance	[2]	$ 10,250		$ 10,250		$ 10,250
Loss recorded in the Consolidated Statements of Operations	[1],[2]	$ 0	0	$ 0	0
HC Government Realty Trust, Inc [Member] | Common Stock of Investee [Member]
Ownership percentage		7.20%		7.20%		7.70%
Investment in affiliate, balance		$ 1,423		$ 1,423		$ 1,822
Loss recorded in the Consolidated Statements of Operations	[1]	$ (50)	$ (124)	$ (275)	$ (301)

[1] Loss from these investments is included in “Loss from affiliate” in the statement of operations. Since HC Realty is a Real Estate Investment Trust and not a taxable entity, the loss is not reported net of taxes.

[2] Represents investments in shares of HC Realty preferred stock with a basis of $10.25 million. Each share of preferred stock can be converted into one share of HC Realty common stock at a conversion price equal to the lesser of $9.10 per share or the fair market value per share of HC Realty common stock, subject to adjustment upon the occurrence of certain events.