Organization, Ownership and Basis of Presentation (Details) - Mar. 31, 2019	ft²	residential_unit	Total	project	tenant	building	property
Office properties [Member]
Real Estate Properties [Line Items]
Number of Buildings						94	4
Rentable Square Feet	13,236,373
Number of Tenants | tenant					473
Percentage Occupied			92.50%
Percentage Leased			96.20%
Stabilized Residential Properties [Member]
Real Estate Properties [Line Items]
Number of Buildings | building						1
Percentage Occupied			72.80%
Number of Units | building						200
In-process development projects - tenant improvement [Member]
Real Estate Properties [Line Items]
Number of Buildings | project				3
Rentable Square Feet	1,246,000
In-process development projects - under construction [Member]
Real Estate Properties [Line Items]
Number of Buildings | project				5
Rentable Square Feet	2,080,000
Retail site [Member] | In-process development projects - under construction [Member]
Real Estate Properties [Line Items]
Rentable Square Feet	96,000
Number of residential units | residential_unit		801
Retail site [Member] | Production, Distribution and Repair (PDR) [Member]
Real Estate Properties [Line Items]
Rentable Square Feet	88,000