Commitments and Contingencies - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) ground_lease	Mar. 31, 2019 USD ($)
Long-term Purchase Commitment [Line Items]
Commitments for contracts and executed leases, operating and redevelopment and development properties	$ 913.0
Weighted average discount rate, ground leases	5.11%
Weighted average remaining lease term	55 years
Variable lease, cost	$ 0.9	$ 0.7
Environmental matters [Member]
Long-term Purchase Commitment [Line Items]
Accrued environmental remediation liabilities	$ 81.0
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