v3.22.1

Cover - USD ($) $ in Billions	12 Months Ended
Cover - USD ($) $ in Billions	Dec. 31, 2021	Mar. 22, 2022	Jun. 30, 2021
Document Information [Line Items]
Document Type	10-K/A
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2021
Current Fiscal Year End Date	--12-31
Entity File Number	001-35789
Entity Registrant Name	CyrusOne Inc.
Entity Central Index Key	0001553023
Entity Tax Identification Number	46-0691837
Entity Incorporation, State or Country Code	MD
Entity Address, Address Line One	2850 N. Harwood Street
Entity Address, Address Line Two	Suite 2200
Entity Address, City or Town	Dallas
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75201
City Area Code	972
Local Phone Number	350-0060
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
Entity Shell Company	false
Entity Public Float			$ 8.9
Entity Common Stock, Shares Outstanding		131,149,400
ICFR Auditor Attestation Flag	true
Auditor Name	Deloitte & Touche LLP
Auditor Location	Dallas, Texas
Auditor Firm ID	34
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $.01 par value
Trading Symbol	CONE
Security Exchange Name	NASDAQ
1.450% Senior Notes due 2027
Document Information [Line Items]
Title of 12(b) Security	1.450% Senior Notes due 2027
Trading Symbol	CONE27
Security Exchange Name	NASDAQ

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CyrusOne Inc. 10-K/A