CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
LIABILITIES, MEZZANINE EQUITY, AND EQUITY
Preferred shares of beneficial interest, shares outstanding (in shares)	3,900,000	3,900,000
Preferred shares liquidation preference	$ 97,000
Common shares of beneficial interest, shares issued (in shares)	14,045,000	13,027,000
Common shares of beneficial interest, shares outstanding (in shares)	14,045,000	13,027,000
Noncontrolling interests - operating partnership (in shares)	881,000	977,000
Series D Preferred Units
LIABILITIES, MEZZANINE EQUITY, AND EQUITY
Preferred units, par value (in dollars per share)	$ 100	$ 100
Preferred units, shares issued (in shares)	166,000	166,000
Preferred units, shares outstanding (in shares)	166,000	166,000
Preferred units, liquidation preference	$ 16,560	$ 16,560
Series C Preferred Shares Of Beneficial Interest
LIABILITIES, MEZZANINE EQUITY, AND EQUITY
Preferred shares, liquidation preference (in dollars per share)	$ 25.00	$ 25
Preferred units, shares issued (in shares)	3,881,000	3,881,000
Preferred shares of beneficial interest, shares outstanding (in shares)	3,881,000	3,881,000
Preferred shares liquidation preference	$ 97,036	$ 97,036
Term Loans
LIABILITIES
Unamortized loan costs	714	754
Mortgages
LIABILITIES
Unamortized loan costs	$ 1,220	$ 1,371