Commitments and Contingencies - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) community property Lease	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) community property Lease	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Number Of Office Leases | Lease	15		15
Operating lease assets	$ 135,885		$ 135,885		$ 103,063
Operating lease obligation	162,683		162,683		120,261
Operating Lease, Expense	3,958	$ 3,618	12,115	$ 10,723
Finance lease asset	21,738		21,738		21,898
Finance lease obligation	$ 20,176		$ 20,176		$ 20,207
Properties on Land Subject to Land Leases
Lessee, Lease, Description [Line Items]
Number Of operating apartment communities owned | community	11		11
Number of operating apartment communities under construction | community	1		1
Number of commercial properties owned | property	2		2
Assets Held under Operating Leases [Member]
Lessee, Lease, Description [Line Items]
Number Of operating apartment communities owned | community	10		10
Assets Held under Finance Leases [Member]
Lessee, Lease, Description [Line Items]
Number Of operating apartment communities owned | community	1		1
Number Of Finance Leases For Parking Garages Adjacent To Communities | Lease	2		2