Capital and Accumulated Other Comprehensive Loss (Partnership Units Narrative) (Details) $ in Millions	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Class of Stock [Line Items]
Common stock conversion ratio	1
Digital Realty Trust, L.P.
Class of Stock [Line Items]
Common stock conversion ratio	1
Redeemable noncontrolling interests – operating partnership	$ 891.0	$ 887.0

Redemption value, as if currently redeemable, of redeemable noncontrolling interest classified as temporary equity and the election has been made to accrete changes in redemption value to the earliest redemption date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section S99
-Paragraph 3A
-Subparagraph 24(b)
-URI http://asc.fasb.org/extlink&oid=65877616&loc=SL6540498-122764

Name:	us-gaap_RedeemableNoncontrollingInterestEquityRedemptionValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant