Segment Information (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 segment	Jun. 30, 2011	Dec. 31, 2011
Segment Information
Number of reportable segments			2
Segment information
Total revenues:	$ 349,005,000	$ 298,705,000	$ 688,197,000	$ 627,927,000
Income from continuing operations before equity in net gain on sale of unconsolidated joint venture and purchase price fair value adjustments	108,923,000	26,324,000	130,271,000	104,554,000
Total assets:	14,139,113,000		14,139,113,000		13,483,852,000
Leverage rate assumption (as a percent)	100.00%
Marketing, general and administrative expenses and transaction related costs	22,700,000	23,700,000	44,000,000	46,100,000
Real Estate Segment
Segment information
Total revenues:	315,557,000	283,561,000	628,411,000	548,104,000
Income from continuing operations before equity in net gain on sale of unconsolidated joint venture and purchase price fair value adjustments	81,910,000	14,358,000	82,343,000	28,226,000
Total assets:	13,141,444,000		13,141,444,000		12,490,502,000
Debt and Preferred Equity Segment
Segment information
Total revenues:	33,448,000	15,144,000	59,786,000	79,823,000
Income from continuing operations before equity in net gain on sale of unconsolidated joint venture and purchase price fair value adjustments	27,013,000	11,966,000	47,928,000	76,328,000
Total assets:	$ 997,669,000		$ 997,669,000		$ 993,350,000