Note 9 - Fair Value of Financial Instruments - Carrying Amount and Fair Value of Mortgage Notes Payable (Details) - Mortgages [Member] - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Reported Value Measurement [Member]
Mortgage notes payable	$ 1,091,057	$ 1,009,431
Estimate of Fair Value Measurement [Member]
Mortgage notes payable	$ 1,219,543	$ 1,058,083

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

No definition available.

Name:	us-gaap_LongTermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant