Note 4 - Investment in Affiliate - Equity Method Investments (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Investment in affiliate, balance		$ 12,396		$ 12,396		$ 4,405
Loss recorded in the Consolidated Statements of Operations		$ (69)	$ (122)	$ (177)	$ (141)
HC Government Realty Trust, Inc [Member]
Equity Method Investment, Ownership Percentage		36.20%		36.20%		16.40%
Investment in affiliate, balance		$ 12,396		$ 12,396		$ 4,405
Loss recorded in the Consolidated Statements of Operations	[1]	$ (69)	(122)	$ (177)	(141)
HC Government Realty Trust, Inc [Member] | Series B Cumulative Convertible Preferred Stock [Member]
Equity Method Investment, Ownership Percentage	[2]	29.90%		29.90%		7.90%
Investment in affiliate, balance	[2]	$ 10,250		$ 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		6.30%		6.30%		8.50%
Investment in affiliate, balance		$ 2,146		$ 2,146		$ 2,405
Loss recorded in the Consolidated Statements of Operations	[1]	$ (69)	$ (122)	$ (177)	$ (141)

[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 $2 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.