Segment Information - Summary of NOI by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Property rentals	$ 122,326	$ 126,591	$ 241,739	$ 257,819
Property operating	32,113	34,464	64,287	69,622
Real estate taxes	18,266	17,509	35,501	37,119
Operating Segments
Segment Reporting Information [Line Items]
Property rentals	122,326	126,591	241,739	257,819
Other property operating income	6,690	6,616	13,144	12,979
Total rental revenue	129,016	133,207	254,883	270,798
Property operating	32,113	34,464	64,287	69,622
Real estate taxes	18,266	17,509	35,501	37,119
Total rental expense	50,379	51,973	99,788	106,741
Consolidated NOI	78,637	81,234	155,095	164,057
Operating Segments | Commercial Segment [Member]
Segment Reporting Information [Line Items]
Property rentals	94,626	100,167	190,873	205,747
Other property operating income	6,600	6,492	12,974	12,736
Total rental revenue	101,226	106,659	203,847	218,483
Property operating	26,409	27,143	56,889	56,047
Real estate taxes	12,739	12,217	25,252	26,998
Total rental expense	39,148	39,360	82,141	83,045
Consolidated NOI	62,078	67,299	121,706	135,438
Operating Segments | Multifamily
Segment Reporting Information [Line Items]
Property rentals	28,873	26,649	57,123	52,540
Other property operating income	90	97	170	187
Total rental revenue	28,963	26,746	57,293	52,727
Property operating	8,204	7,695	16,172	14,980
Real estate taxes	4,143	3,615	7,692	7,163
Total rental expense	12,347	11,310	23,864	22,143
Consolidated NOI	16,616	15,436	33,429	30,584
Operating Segments | Other
Segment Reporting Information [Line Items]
Property rentals	(1,173)	(225)	(6,257)	(468)
Other property operating income	0	27	0	56
Total rental revenue	(1,173)	(198)	(6,257)	(412)
Property operating	(2,500)	(374)	(8,774)	(1,405)
Real estate taxes	1,384	1,677	2,557	2,958
Total rental expense	(1,116)	1,303	(6,217)	1,553
Consolidated NOI	$ (57)	$ (1,501)	$ (40)	$ (1,965)