Cover page - shares shares in Millions	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-33458
Entity Registrant Name	TERADATA CORP /DE/
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	75-3236470
Entity Address, Address Line One	17095 Via Del Campo
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92127
City Area Code	866
Local Phone Number	548-8348
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	TDC
Security Exchange Name	NYSE
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 Common Stock, Shares Outstanding		109.6
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Central Index Key	0000816761
Current Fiscal Year End Date	--12-31