Cover - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Feb. 22, 2021	Jun. 30, 2020
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-36109
Entity Registrant Name	QTS Realty Trust, Inc.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	46-2809094
Entity Address, Address Line One	12851 Foster Street
Entity Address, City or Town	Overland Park
Entity Address, State or Province	KS
Entity Address, Postal Zip Code	66213
City Area Code	913
Local Phone Number	312-5503
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 3.9
Documents Incorporated by Reference	Portions of the Definitive Proxy Statement for our 2021 Annual Meeting of Stockholders are incorporated by reference into Part III of this report. We expect to file our proxy statement within 120 days after December 31, 2020.
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Central Index Key	0001577368
Amendment Flag	false
Class A Common Stock
Document Information [Line Items]
Title of 12(b) Security	Class A common stock, $.01 par value
Trading Symbol	QTS
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		64,520,050
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		124,995
Series A Redeemable Perpetual Preferred
Document Information [Line Items]
Title of 12(b) Security	Preferred Stock, 7.125% Series A Cumulative Redeemable Perpetual, $0.01 par value
Trading Symbol	QTS.PRA
Security Exchange Name	NYSE
Series B Convertible preferred stock
Document Information [Line Items]
Title of 12(b) Security	Preferred Stock, 6.50% Series B Cumulative Convertible Perpetual, $0.01 par value
Trading Symbol	QTS.PRB
Security Exchange Name	NYSE