Loans Receivable (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Summary of Trust's loans receivable
Loans receivable, net	$ 130,212,000	$ 211,250,000
Hotel Wales [Member] | Whole Loan [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	LIBOR + 4.0%
Interest rate on mortgage loans	4.00%
Loans receivable, net	20,101,000	20,101,000
Contractual maturity date	Oct. 05, 2013
Renaissance Walk [Member] | Mezzanine [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	LIBOR + 12.0%
Interest rate on mortgage loans	12.00%
Loans receivable, net	3,000,000	3,000,000
Contractual maturity date	Jan. 01, 2014
Fenway Shea [Member] | Whole Loan [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	12.0%
Interest rate on mortgage loans	12.00%
Loans receivable, net	2,273,000	2,273,000
Contractual maturity date	Apr. 05, 2014
The Shops At Wailea [Member] | B Note [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	6.15%
Interest rate on mortgage loans	6.15%
Loans receivable, net	5,573,000	5,376,000
Contractual maturity date	Oct. 06, 2014
Legacy Orchard [Member] | Corporate Loan [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	15.0%
Interest rate on mortgage loans	15.00%
Loans receivable, net	9,750,000	9,750,000
Contractual maturity date	Oct. 31, 2014
Queensridge [Member]
Summary of Trust's loans receivable
Loans receivable, net	28,976,000
Queensridge [Member] | Whole Loan [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	LIBOR + 11.5%
Interest rate on mortgage loans	11.50%
Loans receivable, net	28,976,000	39,170,000
Contractual maturity date	Nov. 15, 2014
San Marbeya [Member] | Whole Loan [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	5.88%
Interest rate on mortgage loans	5.88%
Loans receivable, net	27,323,000	27,149,000
Contractual maturity date	Jan. 01, 2015
Playa Vista [Member] | Mezzanine [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	LIBOR + 14.25%
Interest rate on mortgage loans	14.25%
Loans receivable, net	10,323,000
Contractual maturity date	Jan. 23, 2015
Churchill [Member] | Whole Loan [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	LIBOR + 3.75%
Interest rate on mortgage loans	3.75%
Loans receivable, net	687,000	683,000
Contractual maturity date	Jun. 01, 2015
Rockwell [Member] | Mezzanine [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	12.0%
Interest rate on mortgage loans	12.00%
Loans receivable, net	342,000	323,000
Contractual maturity date	May 01, 2016
500-512 7th Avenue [Member] | B Note [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	7.19%
Interest rate on mortgage loans	7.19%
Loans receivable, net	10,013,000	10,009,000
Contractual maturity date	Jul. 11, 2016
Pinnacle II [Member] | B Note [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	6.31%
Interest rate on mortgage loans	6.31%
Loans receivable, net	4,648,000	4,652,000
Contractual maturity date	Sep. 06, 2016
Popiu Shopping Village [Member] | B Note [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	6.62%
Interest rate on mortgage loans	6.62%
Loans receivable, net	1,972,000	1,948,000
Contractual maturity date	Jan. 06, 2017
Wellington Tower [Member] | Mezzanine [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	6.79%
Interest rate on mortgage loans	6.79%
Loans receivable, net	2,719,000	2,687,000
Contractual maturity date	Jul. 11, 2017
Mentor Building [Member] | Whole Loan [Member]
Summary of Trust's loans receivable
Mortgage Loans, Stated Interest Rate, Variable Rate Basis	10.0%
Interest rate on mortgage loans	10.00%
Loans receivable, net	2,512,000	2,512,000
Contractual maturity date	Sep. 10, 2017
1515 Market [Member] | Whole Loan [Member]
Summary of Trust's loans receivable
Loans receivable, net		58,650,000
127 West 25th Street [Member] | Mezzanine [Member]
Summary of Trust's loans receivable
Loans receivable, net		8,687,000
180 N. Michigan [Member] | Mezzanine [Member]
Summary of Trust's loans receivable
Loans receivable, net		5,237,000
The Disney Building [Member] | B Note [Member]
Summary of Trust's loans receivable
Loans receivable, net		$ 9,043,000