Share-Based Compensation (Schedule of Share-Based Compensation Information) (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Based Compensation [Abstract]
Expense relating to share/unit grants	$ 629,000		$ 822,000	$ 2,650,000	$ 2,930,000
Amounts capitalized	(46,000)		(55,000)	(141,000)	(177,000)
Total charged to operations	$ 583,000		$ 767,000	$ 2,509,000	$ 2,753,000
Unvested shares/units, December 31, 2020		642,000		642,000
Restricted share grants		144,000
Vested during period		(239,000)
Forfeitures/cancellations		(40,000)
Unvested shares/units, March 31, 2021		507,000
Unvested shares/unit, December 31, 2020, weighted average grant date fair value		$ 25.86		$ 25.86
Restricted share grants, weighted average grant date fair value		11.68
Vested during period, weighted average grant date fair value		22.71
Forfeitures/cancellations, weighted average grant date fair value		17.20
Unvested shares/unit, March 31, 2021, weighted average grant date fair value		$ 24.00