Summary Of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011
Increase (Decrease) in Temporary Equity [Roll Forward]
Beg Bal Redeemable Noncontrolling Interest, Equity, Fair Value	$ 65,362	$ 57,325		$ 85,325
Temporary Equity, Net Income	3,492	2,986
Redeemable Noncontrolling Interests Distributions	(3,020)	(2,984)
Redeemable Noncontrolling Interests Contributions	10,064	0
Temporary Equity, Other Changes	9,427	8,035
Total interest costs incurred	106,562	108,167	114,330
Interest capitalized	(8,097)	(6,285)	(5,549)
Interest expense	98,465	101,882	108,781
Cash paid for interest, net of amounts capitalized	95,424	98,932	102,106
Cash paid for income taxes	832	255	324
Mortgage loan assumed/entered into with acquisition	308,506		0
Deconsolidation of VIE	18,311		0
Capital lease obligations	4,556
Extinguishment of deferred ground rent liability	0	8,832	0
Extinguishment of capital lease obligation	0	1,031	0
Acquisition of real estate through exchange transaction	0	0	30,100
Proceeds from sale of real estate through exchange transaction	0	0	25,100
Liability assumed through exchange transaction	$ 0	$ 0	$ 5,000