Acquisitions (Details) $ in Millions					1 Months Ended
	Jan. 23, 2019 USD ($) a	Apr. 20, 2018 USD ($) ft²	Aug. 29, 2017 USD ($) a	Nov. 10, 2016 USD ($) a ft²	Jan. 31, 2018 USD ($) a	Jan. 29, 2018 ft²
Acquisitions
Purchase price				$ 65.0
Area of land acquired | a				21.75
Net rentable space | ft²				890,000
SV8 Santa Clara CA
Acquisitions
Purchase price			$ 12.2
Area of land acquired | a			2
SV9 Santa Clara CA | Subsequent Event | Forecast
Acquisitions
Purchase price	$ 26.0
Area of land acquired | a	3.8
CH2 Chicago IL
Acquisitions
Purchase price					$ 4.5
Area of land acquired | a					2
Net rentable space | ft²						175,000
US Colo Los Angeles California
Acquisitions
Purchase price		$ 6.3
L A1 Facility Los Angeles CA
Acquisitions
Net Leased Space | ft²		6,723
LA4 Los Angeles CA
Acquisitions
Net Leased Space | ft²		21,850