Real Estate - Leasing Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Leasing as a Lessor
Cumulative effect adjustment upon adoption of new accounting standard		$ 906
Leasing as a Lessee
Operating ground lease remaining lease term (in years)	52 years
Variable rental payments	$ 200
Lease liability	$ 4,157
Operating lease discount rate	5.90%
Right-of-use asset and lease liability amortization	$ 100
Prepaid expenses and other assets	$ 116,718		$ 132,322
Multifamily Properties
Leasing as a Lessor
Lessor operating lease terms (in years)	1 year
Commercial Office and Retail Properties
Leasing as a Lessor
Lessor operating lease terms (in years)	7 years
ASU No. 2016-02
Leasing as a Lessor
Cumulative effect adjustment upon adoption of new accounting standard		900
Leasing as a Lessee
Lease liability		4,200
Right-of-use asset		4,200
Below Market Ground Lease
Leasing as a Lessee
Accumulated amortization on lease intangible asset prior to derecognition			$ 2,100
Below Market Ground Lease | ASU No. 2016-02 | Reclassification Adjustment
Leasing as a Lessee
Below market ground lease reclassified		$ 10,000