Basis of Presentation and Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Basis of Presentation and Significant Accounting Policies [Abstract]

Buildings, improvements, and tenant improvements depreciation

The costs of buildings and improvements and tenant improvements are depreciated using the straight-line method of accounting over the estimated useful lives set forth in the table below. Depreciation expense for buildings and improvements for the three years ended December 31, 2020, 2019, and 2018 was $244.8 million, $211.9 million, and $198.6 million, respectively.

Asset Description	Depreciable Lives
Buildings and improvements	25 – 40 years
Tenant improvements	1 – 20 years (1)

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(1)Tenant improvements are amortized over the shorter of the lease term or the estimated useful life.