Commitments and Contingencies - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) community Lease property	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) community Lease property	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Number Of Office Leases | Lease	14		14
Operating lease assets	$ 138,113		$ 138,113		$ 103,063
Operating lease obligation	163,321		163,321		120,261
Operating Lease, Expense	4,240	$ 3,568	8,157	$ 7,105
Financing lease asset	21,791		21,791		21,898
Financing lease obligation	$ 20,186		$ 20,186		$ 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
Number of Finance Leases for Parking Garage Adjacent to Operating Community | Lease	1		1
Number of Finance Leases for Parking Garage Adjacent to Development Community | Lease	1		1