Income per Share (Schedule of Antidilutive Securities Excluded From Computation Of Earnings Per Share) (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	13,559,863	16,421,253	20,118,783
Weighted average of Operating Partnership common units not owned by Digital Realty Trust, Inc.
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	3,996,550	2,406,018	2,658,291
Potentially dilutive Series C Cumulative Redeemable Perpetual Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	540,773	0	0
Potentially dilutive Series E Cumulative Redeemable Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	0	2,880,254	4,301,438
Potentially dilutive Series F Cumulative Redeemable Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	463,301	1,939,905	2,727,962
Potentially dilutive Series G Cumulative Redeemable Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	2,261,153	2,652,503	3,730,042
Potentially dilutive Series H Cumulative Redeemable Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	3,313,484	3,886,966	5,465,987
Potentially dilutive Series I Cumulative Redeemable Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	2,263,799	2,655,607	1,235,063
Potentially dilutive Series J Cumulative Redeemable Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	720,803	0	0