Management Agreement (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2007
Management Fees:
Total Management fee	$ 10,900,000	$ 10,000,000	$ 8,300,000
Incentive fee installment recorded as prepaid management fee	19,047,949	19,047,949
Deferred revenue recognized on transfer of control of 450 West 33rd Street property	77,123,133	77,123,133		77,100,000
ACM
Management Agreement
Incentive fee calculation percentage	25.00%
Percentage of loan loss reserve recoveries used in calculation of incentive fee	60.00%
Period during which the loan loss reserve recoveries are to be taken into consideration for calculation of incentive fee	3 years
Annual interest rate used in computation of incentive fee (as a percent)	9.50%
Term of U.S. Treasury Rate used in computation of incentive fee	10 years
Basis spread added to the U.S. Treasury Rate for computation of incentive fee (as a percent)	3.50%
Multiplier used in computation of incentive fee	10.00
Termination fee	10,000,000
Renewable period for management agreement	1 year
Prior written notice period for termination	6 months
Period after each fiscal quarter in which the incentive fee is payable	60 days
Number of days during the end of fiscal quarter with respect to which incentive fee is being paid	20 days
Management Fees:
Base	10,900,000	10,000,000	8,300,000
Total Management fee	10,900,000	10,000,000	8,300,000
Base management fee expenses due to related party	2,800,000	3,100,000
Incentive fee installment recorded as prepaid management fee				$ 19,000,000
ACM | Minimum
Management Agreement
Percentage of services provided by asset management group per quarter over the level of activity anticipated based on which base management fee can be negotiated in good faith	15.00%
Percentage of incentive fee paid by issuance of common stock shares	25.00%