Segment Information - Summary of NOI by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Operating Leases, Income Statement, Lease Revenue		$ 513,447	$ 451,541
Other property operating income			23,069
Total rental revenue			474,610
Direct Costs of Leased and Rented Property or Equipment	$ 137,622	148,081	118,836
Real estate taxes	70,493	71,054	66,434
Total rental expense			185,270
Consolidated NOI			289,340
Operating Segments
Segment Reporting Information [Line Items]
Operating Leases, Income Statement, Lease Revenue	493,273	513,447
Other property operating income	25,973	25,678
Total rental revenue	519,246	539,125
Direct Costs of Leased and Rented Property or Equipment	137,622	148,081
Real estate taxes	70,493	71,054
Total rental expense	208,115	219,135
Consolidated NOI	311,131	319,990
Operating Segments | Commercial Segment [Member]
Segment Reporting Information [Line Items]
Operating Leases, Income Statement, Lease Revenue	383,311	404,826	361,121
Other property operating income	25,593	25,216	22,776
Total rental revenue	408,904	430,042	383,897
Direct Costs of Leased and Rented Property or Equipment	113,177	118,288	97,701
Real estate taxes	50,115	53,324	50,546
Total rental expense	163,292	171,612	148,247
Consolidated NOI	245,612	258,430	235,650
Operating Segments | Multifamily
Segment Reporting Information [Line Items]
Operating Leases, Income Statement, Lease Revenue	116,330	108,989	91,294
Other property operating income	380	368	275
Total rental revenue	116,710	109,357	91,569
Direct Costs of Leased and Rented Property or Equipment	35,236	31,502	24,623
Real estate taxes	15,021	14,280	11,030
Total rental expense	50,257	45,782	35,653
Consolidated NOI	66,453	63,575	55,916
Operating Segments | Other
Segment Reporting Information [Line Items]
Operating Leases, Income Statement, Lease Revenue	(6,368)	(368)	(874)
Other property operating income	0	94	18
Total rental revenue	(6,368)	(274)	(856)
Direct Costs of Leased and Rented Property or Equipment	(10,791)	(1,709)	(3,488)
Real estate taxes	5,357	3,450	4,858
Total rental expense	(5,434)	1,741	1,370
Consolidated NOI	$ (934)	$ (2,015)	$ (2,226)