Capital and Accumulated Other Comprehensive Income (Loss) (Forward Equity Sale Narrative) (Details) - Digital Realty Trust, L.P. - USD ($) $ in Millions	Sep. 27, 2019	Sep. 27, 2018	May 19, 2017	Sep. 27, 2016	Jun. 02, 2016	May 20, 2016
Forward Sale Agreement
Subsidiary, Sale of Stock [Line Items]
Number of shares issued (in shares)		9,775,000		12,000,000	14,375,000	12,500,000
Proceeds from sale of stock			$ 211.1	$ 1,100.0
Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Number of shares issued (in shares)		1,275,000			1,875,000
Scenario, Forecast | Forward Sale Agreement
Subsidiary, Sale of Stock [Line Items]
Proceeds from sale of stock	$ 1,100.0