Share-Based Compensation (Schedule of Share-Based Compensation Information) (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share Based Compensation [Abstract]
Expense relating to share/unit grants	$ 1,092,000		$ 1,031,000	$ 2,021,000	$ 2,108,000
Amounts capitalized	(46,000)		(59,000)	(95,000)	(122,000)
Total charged to operations	$ 1,046,000		$ 972,000	$ 1,926,000	$ 1,986,000
Unvested shares/units, December 31, 2020	659,000	642,000		642,000
Restricted share grants		119,000
Vested during period		(95,000)
Forfeitures/cancellations		(7,000)
Unvested shares/units, March 31, 2021		659,000
Unvested shares/unit, December 31, 2020, weighted average grant date fair value	$ 22.01	$ 25.86		$ 25.86
Restricted share grants, weighted average grant date fair value		10.58
Vested during period, weighted average grant date fair value		34.11
Forfeitures/cancellations, weighted average grant date fair value		16.63
Unvested shares/unit, March 31, 2021, weighted average grant date fair value		$ 22.01