Note 5 - Investment in Affiliate - Equity Method Investments (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019
Investment in affiliate, balance		$ 12,072	$ 4,405
Loss recorded in the Consolidated Statements of Operations		$ (418)	$ (430)
HC Government Realty Trust, Inc [Member]
Equity Method Investment, Ownership Percentage		36.40%	16.40%
Investment in affiliate, balance		$ 12,072	$ 4,405
Loss recorded in the Consolidated Statements of Operations	[1]	$ (418)	$ (430)
HC Government Realty Trust, Inc [Member] | Series B Cumulative Convertible Preferred Stock [Member]
Equity Method Investment, Ownership Percentage	[2]	28.70%	7.90%
Investment in affiliate, balance	[2]	$ 10,250	$ 2,000
Loss recorded in the Consolidated Statements of Operations	[1],[2]
HC Government Realty Trust, Inc [Member] | Common Stock of Investee [Member]
Equity Method Investment, Ownership Percentage		7.70%	8.50%
Investment in affiliate, balance		$ 1,822	$ 2,405
Loss recorded in the Consolidated Statements of Operations	[1]	$ (418)	$ (430)

[1] Loss from these investments is included in "Loss from affiliate" in the statements 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.