Organization (Public Offering) (Details) shares in Millions, ft² in Millions	12 Months Ended			67 Months Ended
	Dec. 31, 2019 USD ($) ft² Property	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Mar. 30, 2020 USD ($) shares	Dec. 06, 2017 USD ($)	Sep. 30, 2017 USD ($)	Aug. 20, 2014 USD ($)
Public Offering
Proceeds from issuance of common stock	$ 392,897,000	$ 44,324,000	$ 138,192,000
Number of real estate properties | Property	19
Area of real estate property | ft²	9.4
Portfolio, percentage leased	96.00%
Dividend Reinvestment Plan | Initial Offering
Public Offering
Maximum proceeds authorized for public offering						$ 150,000,000.0
Dividend Reinvestment Plan | Follow-on Offering
Public Offering
Maximum proceeds authorized for public offering					$ 500,000,000.0
IPO
Public Offering
Maximum proceeds authorized for public offering							$ 2,500,000,000
Follow-on Offering
Public Offering
Maximum proceeds authorized for public offering					$ 2,500,000,000
First And Second Offerings | First And Second Offerings | Subsequent Event
Public Offering
Proceeds from issuance of common stock				$ 985,700,000
Common stock sold (shares) | shares				97.6