Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 segment	Sep. 30, 2013	Dec. 31, 2013
Segment information
Number of reportable segments (segment)			2
Total revenues	$ 390,274	$ 338,782	$ 1,133,351	$ 1,020,614
Income (loss) from continuing operations before equity in net gain on sale of interest in unconsolidated joint venture/real estate	27,556	24,468	130,821	78,412
Total assets	17,237,109		17,237,109		14,959,001
Leverage rate assumption (as a percent)			100.00%
Marketing, general and administrative	22,649	20,869	69,778	63,450
Real Estate Segment
Segment information
Total revenues	346,305	294,334	995,584	876,727
Income (loss) from continuing operations before equity in net gain on sale of interest in unconsolidated joint venture/real estate	(10,542)	(11,391)	13,148	(38,836)
Total assets	15,789,046		15,789,046		13,641,727
Debt and Preferred Equity Segment
Segment information
Total revenues	43,969	44,448	137,767	143,887
Income (loss) from continuing operations before equity in net gain on sale of interest in unconsolidated joint venture/real estate	38,098	35,859	117,673	117,248
Total assets	$ 1,448,063		$ 1,448,063		$ 1,317,274