Significant Accounting Policies (Details3) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Significant Accounting Policies
Days past due for income recognition on debt and preferred equity investments to be suspended (in days)			90
Reserve for Possible Credit Losses
Loan loss and other investment reserves, net of recoveries	$ 1,280,000	$ 4,985,000	$ (1,870,000)	$ 10,985,000
Recoveries recorded	1,200,000		4,370,000		3,662,000
Income taxes
Minimum annual taxable income distributed to stockholders to maintain REIT qualification (as a percent)			90.00%
Federal, state and local tax provision recorded				1,300,000
Estimated federal income tax liability payments			100,000	300,000
Debt and Preferred Equity Investments Held to Maturity Member
Reserve for Possible Credit Losses
Loan loss and other investment reserves, net of recoveries	2,500,000	4,000,000	2,500,000	10,000,000
Debt and Preferred Equity Investments Held for Sale Member
Reserve for Possible Credit Losses
Loan loss and other investment reserves, net of recoveries		$ 1,000,000		$ 1,000,000