Debt and Preferred Equity Investments (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011 item
Debt and Preferred Equity Investments
Number of portfolio segments of financial receivables	1	1
Additional amount of financing receivables	$ 121,300,000	$ 108,700,000
Nonaccrual balance of financing receivables	0	102,600,000
Number of financing receivables past due 90 days		2
Recorded investment for financing receivables past due 90 days		17,300,000
Unpaid Principal Balance
Unpaid Principal Balance	10,750,000	192,744,000
Recorded Investment
Recorded Investment	10,750,000	164,853,000
Allowance Allocated
Allowance Allocated	7,000,000	50,175,000
Average recorded investment in impaired loans	50,231,000	191,288,000
Investment and preferred equity income (loss) recognized	3,712,000	9,554,000
Commercial real estate with no related allowance recorded
Unpaid Principal Balance
With no related allowance recorded		106,623,000
With an allowance recorded	10,750,000	86,121,000
Recorded Investment
With no related allowance recorded		83,378,000
With an allowance recorded	10,750,000	81,475,000
Allowance Allocated
Allowance Allocated	$ 7,000,000	$ 50,175,000