Debt and Preferred Equity Investments (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Loan loss reserve activity
Balance at beginning of year	$ 50,175	$ 61,361	$ 93,844
Expensed	3,000	10,875	24,418
Recoveries	(2,436)	(4,370)	(3,662)
Charge-offs and reclassifications	(43,739)	(17,691)	(53,239)
Balance at end of period	$ 7,000	$ 50,175	$ 61,361