CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2018
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common shares of beneficial interest, shares issued (in shares)	12,163,000	12,098,000
Common shares of beneficial interest, shares outstanding (in shares)	12,163,000	12,098,000
Noncontrolling interests - operating partnership (in shares)	1,043,000	1,058,000
Preferred shares of beneficial interest, liquidation preference (in dollars per share)	$ 25.00
Preferred shares of beneficial interest, shares outstanding (in shares)	4,000,000.0
Preferred shares liquidation preference	$ 99,600
Series D Preferred Units
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
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
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Preferred shares of beneficial interest, par value (in dollars per share)	$ 0	$ 0
Preferred shares of beneficial interest, liquidation preference (in dollars per share)	$ 25	$ 25
Preferred shares of beneficial interest, shares issued (in shares)	3,982,000	4,118,000
Preferred shares of beneficial interest, shares outstanding (in shares)	3,982,000	4,118,000
Preferred shares liquidation preference	$ 99,552	$ 102,971
Term Loans
LIABILITIES
Unamortized loan costs	894	942
Mortgages
LIABILITIES
Unamortized loan costs	$ 1,621	$ 1,712