Related Party Transactions Tax Protection Agreement (Details) (Malkin Group [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 property
Related Party Transaction [Line Items]
Number of properties protected	4
Aggregate number of operating partnership units and common stock threshold during tax protection period	50.00%
Bottom dollar guarantee of aggregate indebtedness during tax protection period	$ 160.0
First Stamford Place [Member]
Related Party Transaction [Line Items]
Protection period	12 years
Other Protected Property [Member]
Related Party Transaction [Line Items]
Number of properties protected	3
Protection period	8 years