Commitment and Contingencies (Details) - USD ($)		1 Months Ended		3 Months Ended
	Aug. 10, 2021	Feb. 29, 2020	Nov. 30, 2019	Jul. 31, 2021	Jul. 31, 2020	Apr. 30, 2021
Long-term Purchase Commitment [Line Items]
Purchase commitment, incurred cost				$ 3,200,000	$ 2,600,000
Blattman et al. v. Siebel et al. | Pending Litigation | Subsequent Event
Long-term Purchase Commitment [Line Items]
Recommended amount to be awarded from other party	$ 9,700,000
Requested by plaintiff, amount to be awarded from other party	$ 8,300,000
C3.ai DTI Grants Program
Long-term Purchase Commitment [Line Items]
Grants, payment period		5 years
Grants, potential remaining contributions				$ 40,200,000		$ 43,100,000
Web-Hosting Services, November 2019-November 2022
Long-term Purchase Commitment [Line Items]
Purchase commitment			$ 30,000,000
Purchase commitment, term			3 years
Web-Hosting Services, November 2020
Long-term Purchase Commitment [Line Items]
Purchase commitment			$ 10,000,000
Web-Hosting Services, November 2021
Long-term Purchase Commitment [Line Items]
Purchase commitment			10,000,000
Web-Hosting Services, November 2022
Long-term Purchase Commitment [Line Items]
Purchase commitment			$ 10,000,000