Investments in Unconsolidated Joint Ventures (Details 4) (Gramercy Property Trust Inc., USD $) Share data in Millions, unless otherwise specified		6 Months Ended			1 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 First Gramercy lease sqft	Jun. 30, 2013 Second Gramercy lease sqft	Jun. 30, 2013 Third Gramercy lease sqft	Jun. 30, 2012 New lease sqft
Related party transactions
Shares held of Gramercy's common stock	0.7
Percentage of Gramercy's common stock owned	1.35%
Total investment in Gramercy	$ 3,400,000
Space leased (in square feet)		7,300	900	1,400	8,100
Term of lease		10 years
Annual lease rent for year one		249,000	35,300	67,300	345,000
Annual lease rent for year ten		315,000
Annual lease rent for year six			42,800	80,500
Annual lease rent for year three					$ 357,000