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Real Estate and Accumulated Depreciation (Parenthetical) (Detail)
$ in Millions
12 Months Ended
Dec. 31, 2016
USD ($)
Real Estate And Accumulated Depreciation [Line Items]  
Tax cost basis of assets $ 9,800.0
Real estate land under development 55.0
Real estate construction in progress 50.4
Fair market value of debt adjustments and unamortized debt issuance costs $ 3.8
Tenant improvements [Member]  
Real Estate And Accumulated Depreciation [Line Items]  
Estimated useful lives of the assets Shorter of economic life or lease terms
Minimum [Member] | Buildings [Member]  
Real Estate And Accumulated Depreciation [Line Items]  
Estimated useful lives of the assets 20 years
Minimum [Member] | Building Improvements and Fixtures [Member]  
Real Estate And Accumulated Depreciation [Line Items]  
Estimated useful lives of the assets 5 years
Maximum [Member] | Buildings [Member]  
Real Estate And Accumulated Depreciation [Line Items]  
Estimated useful lives of the assets 31 years 6 months
Maximum [Member] | Building Improvements and Fixtures [Member]  
Real Estate And Accumulated Depreciation [Line Items]  
Estimated useful lives of the assets 20 years