Commitments and Contingencies - Narrative (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) community Lease property
Lessee, Lease, Description [Line Items]
Number of office leases | Lease	14
Number of leases not yet commenced | Lease	1
Operating lease assets	$ 102,312
Operating lease obligation	120,202
Operating leases, rent expense	3,537
Financing lease asset	22,057
Financing lease obligation	$ 20,234
Properties on Land Subject to Land Leases
Lessee, Lease, Description [Line Items]
Number of operating apartment communities owned | community	11
Number of operating apartment communities under construction | community	1
Number of commercial properties owned | property	2
Number of leased properties under purchase options | property	5
Assets Held under Finance Leases [Member]
Lessee, Lease, Description [Line Items]
Number of operating apartment communities owned | community	1