Loans and Other Lending Investments, net (Details 3) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2012 rating	Dec. 31, 2011 rating
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	$ 2,859,344	$ 3,504,861
Senior mortgages
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	2,243,285
Subordinate mortgages
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	150,629
Corporate/Partnership loans
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	465,430
Performing Loans
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	1,729,088	2,176,536
Weighted Average Risk Ratings	3.16	3.29
Performing Loans | Senior mortgages
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	1,176,248	1,514,016
Weighted Average Risk Ratings	3.00	3.19
Performing Loans | Subordinate mortgages
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	97,520	190,342
Weighted Average Risk Ratings	2.41	3.36
Performing Loans | Corporate/Partnership loans
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	$ 455,320	$ 472,178
Weighted Average Risk Ratings	3.73	3.61