Commitment and Contingencies (Details) - USD ($)			1 Months Ended		12 Months Ended
	Dec. 06, 2021	Aug. 10, 2021	Feb. 29, 2020	Nov. 30, 2019	Apr. 30, 2022	Apr. 30, 2021	Apr. 30, 2020
Long-term Purchase Commitment [Line Items]
Purchase commitment, incurred cost					$ 13,900,000	$ 14,300,000	$ 4,400,000
Blattman et al. v. Siebel et al. | Pending Litigation
Long-term Purchase Commitment [Line Items]
Recommended amount to be awarded from other party		$ 9,700,000
Amount to be award from other party requested by plaintiff		$ 8,300,000
Blattman et al. v. Siebel et al. | Settled Litigation
Long-term Purchase Commitment [Line Items]
Amount awarded from other party	$ 9,400,000
Blattman et al. v. Siebel et al. | Settled Litigation | Other Nonoperating Income (Expense)
Long-term Purchase Commitment [Line Items]
Amount awarded from other party					9,400,000
C3.ai DTI Grants Program
Long-term Purchase Commitment [Line Items]
Grants, payment period (in years)			5 years
Grants, potential remaining contributions					$ 31,600,000	$ 43,100,000
Web-Hosting Services, November 2019-November 2022
Long-term Purchase Commitment [Line Items]
Purchase commitment				$ 30,000,000
Purchase commitment, term (in years)				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