Commitments and Contingencies - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) ground_lease	Dec. 31, 2019 USD ($)
Long-term Purchase Commitment [Line Items]
Commitments for contracts and executed leases, operating and redevelopment and development properties	$ 614.9
Weighted average discount rate	5.11%
Weighted average remaining lease term	54 years
Variable lease, cost	$ 3.0	$ 2.9
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	five 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%
Ground lease fixed ground rent increase, percent	5.00%
Ten year ground lease extension option [Member]
Long-term Purchase Commitment [Line Items]
Number of extension options | ground_lease	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 | ground_lease	1
Ground lease extension option term	45 years
Environmental matters [Member]
Long-term Purchase Commitment [Line Items]
Accrued environmental remediation liabilities	$ 71.3	$ 80.7