Investment in Unconsolidated Joint Ventures (Details 4) (Gramercy Capital Corp., USD $) Share data in Millions, unless otherwise specified	12 Months Ended						12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 First Gramercy lease sqft	Dec. 31, 2012 Second Gramercy lease sqft	Dec. 31, 2012 New Gramercy lease	Jun. 30, 2012 New Gramercy lease sqft	Dec. 31, 2012 Third Gramercy lease sqft
Related Party Transactions
Shares held of Gramercy's common stock	0.7
Percentage of Gramercy's common stock owned	1.30%
Total investment in Gramercy based on market value of common stock	$ 2,200,000
Space leased (in square feet)			7,300	900		8,100	1,400
Term of lease			10 years
Annual lease rent for year one			249,000	35,300	345,000		67,300
Annual lease rent for year three					357,000
Annual lease rent for year ten			315,000
Annual lease rent for year six				42,800			80,500
Shares of Gramercy's common stock sold (in shares)	2.5	2.1
Net proceeds Gramercy's common stock sold	6,800,000
Realized gain on sale	$ 4,900,000	$ 4,500,000