Loans Receivable and Other Lending Investments, net (Credit Characteristics by Payment Status) (Details) $ in Thousands		6 Months Ended
		Jun. 30, 2015 USD ($) Loan	Dec. 31, 2014 USD ($)
Recorded investment in loans, aged by payment status and presented by class
Current		$ 1,410,001
Less Than and Equal to 90 Days		6,083
Greater Than 90 Days	[1]	116,230
Total Past Due		122,313
Loans		$ 1,532,314	$ 1,295,703
Financing receivable, number of loans greater than 90 days past due | Loan		4
Financing receivables, past due time period		90 days
Senior mortgages
Recorded investment in loans, aged by payment status and presented by class
Current		$ 766,515
Less Than and Equal to 90 Days		6,083
Greater Than 90 Days	[1]	116,230
Total Past Due		122,313
Loans		888,828
Corporate/Partnership loans
Recorded investment in loans, aged by payment status and presented by class
Current		614,354
Less Than and Equal to 90 Days		0
Greater Than 90 Days		0
Total Past Due		0
Loans		614,354
Subordinate mortgages
Recorded investment in loans, aged by payment status and presented by class
Current		29,132
Less Than and Equal to 90 Days		0
Greater Than 90 Days		0
Total Past Due		0
Loans		$ 29,132
Minimum
Recorded investment in loans, aged by payment status and presented by class
Financing receivables, past due time period		1 year
Maximum
Recorded investment in loans, aged by payment status and presented by class
Financing receivables, past due time period		7 years

[1] As of June 30, 2015, the Company had four loans which were greater than 90 days delinquent and were in various stages of resolution, including legal proceedings, environmental concerns and foreclosure-related proceedings, and ranged from 1.0 to 7.0 years outstanding.