Components of Rental Income and Expense (Components Of Rental Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components Of Rental Income and Expense [Abstract]
Repairs and maintenance	$ 67,745	$ 67,996	$ 64,942
Utilities	27,635	25,763	24,968
Management fees and costs	24,024	22,297	20,823
Payroll	16,140	14,922	13,832
Marketing	7,935	9,007	8,520
Insurance	7,547	7,762	7,758
Bad debt expense	4,708	2,591	2,375
Ground rent	4,697	3,826	2,561
Other operating	12,663	10,726	12,547
Total rental expenses	$ 173,094	$ 164,890	$ 158,326