Loans Receivable and Other Lending Investments, net (Credit Characteristics for Performing Loans) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	$ 1,132,844	$ 1,611,927
Senior mortgages
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	591,241
Subordinate mortgages
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	47,019
Corporate/Partnership loans
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	494,584
Real Estate Finance
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	952,883	1,091,340
Weighted Average Risk Ratings	3.21	3.11
Real Estate Finance | Senior mortgages
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	411,280	591,145
Weighted Average Risk Ratings	2.50	2.50
Real Estate Finance | Subordinate mortgages
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	47,019	61,364
Weighted Average Risk Ratings	2.89	3.37
Real Estate Finance | Corporate/Partnership loans
Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating
Performing Loans	$ 494,584	$ 438,831
Weighted Average Risk Ratings	3.83	3.88