Segment Reporting (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jan. 19, 2011
Net real estate and secured note payable balances
Net Real Estate	$ 1,478,731	$ 1,452,681
Secured notes payable	964,538	943,479	342,000
Retail [Member]
Net real estate and secured note payable balances
Net Real Estate	655,587	655,450
Secured notes payable	399,044	400,320
Office [Member]
Net real estate and secured note payable balances
Net Real Estate	580,634	551,955
Secured notes payable	348,193	327,331
Multifamily [Member]
Net real estate and secured note payable balances
Net Real Estate	36,947	37,187
Secured notes payable	101,444	101,444
Mixed-Use [Member]
Net real estate and secured note payable balances
Net Real Estate	205,563	208,089
Secured notes payable	$ 130,310	$ 130,310