Commitments and Contingencies (Details 1) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) Extensions	Dec. 31, 2015 USD ($)
Long-term Purchase Commitment [Line Items]
Commitments for contracts and executed leases, operating and redevelopment and development properties	$ 538.6
Period after which ground lease rentals are adjusted based on fair market value and the Consumer Price Index	5 years
Annual ground lease rental obligations limit	$ 1.0
Duration of ground lease prior to increase five years	5 years
Average annual percentage rent for previous five years (percent)	50.00%
Duration of ground lease prior to increase ten years	10 years
Average annual percentage rent for previous ten years (percent)	60.00%
Accrued environmental remediation liabilities	$ 25.1	$ 20.9
Ten year ground lease extension option [Member]
Long-term Purchase Commitment [Line Items]
Number of extension options | Extensions	3
Ground lease extension option term	10 years
Forty-five year ground lease extension option [Member]
Long-term Purchase Commitment [Line Items]
Number of extension options | Extensions	1
Ground lease extension option term	45 years
Property damage litigation case [Member]
Long-term Purchase Commitment [Line Items]
Proceeds from legal settlements	$ 5.0