Noncash Investing and Financing Activities (Details) (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Other Significant Noncash Transactions [Line Items]
Accrued dividends and distributions payable	$ 41,717	$ 43,116
Additions to real estate assets accrued but not yet paid	25,870	13,624
Notes receivable from sale of interest in unconsolidated affiliate		1,001
Distribution of real estate assets from unconsolidated affiliate		12,210
Issuance of additional redeemable noncontrolling preferred joint venture interests		$ 2,146