Employee Stock-based Compensation Plans - Schedule of Composition of Teradata Restricted Stock Grants (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2025 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares (in shares) | shares	6,563
Weighted-average grant date fair value of restricted share unit grants (in usd per share) | $ / shares	$ 22.74
Service-based restricted share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares (in shares) | shares	5,547
Weighted-average grant date fair value of restricted share unit grants (in usd per share) | $ / shares	$ 23.30
Performance-based restricted share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares (in shares) | shares	1,016
Weighted-average grant date fair value of restricted share unit grants (in usd per share) | $ / shares	$ 19.69