Summary of Significant Accounting Policies (Supplemental Consolidated Statements of Cash Flows Information) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental disclosure of cash activities:
Cash paid for interest	$ 23,208,000	$ 23,859,000	$ 22,191,000
Supplemental disclosure of non-cash activities:
Capitalization of interest and financing costs	2,674,000	1,649,000	1,528,000
Buildings and improvements included in accounts payable and accrued liabilites	2,976,000	3,669,000	521,000
Recognition of right-of-use assets and related lease liabilities	$ 703,000	$ 13,778,000
Issuance of OP Units in connection with a land parcel acquisition			$ 975,000