Components of Rental Income and Expense (Components Of Rental Expenses) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Component of Operating Other Cost and Expense [Line Items]
Repairs and maintenance	$ 41,616	$ 41,977	$ 42,278
Utilities	19,213	18,823	18,545
Management fees and costs	15,167	14,989	14,641
Payroll	8,704	8,080	7,909
Bad debt expense	2,151	2,649	6,396
Ground rent	2,189	2,047	3,049
Insurance	6,298	5,282	5,054
Marketing	7,321	6,868	4,789
Other operating	10,101	8,834	7,858
Rental expenses	$ 112,760	$ 109,549	$ 110,519