Summary of Business and Significant Accounting Policies (Details)	12 Months Ended
	Apr. 30, 2024 USD ($) application segment	Apr. 30, 2023 USD ($)	Apr. 30, 2022 USD ($)
Subsidiary, Sale of Stock [Line Items]
Restricted cash	$ 12,600,000	$ 12,600,000
Allowance for doubtful accounts	400,000	400,000
Unbilled receivables	62,300,000	77,600,000
Long-lived assets, impairment	0	0	$ 0
Goodwill, impairment	0	0	0
Capitalized software costs	4,300,000	3,000,000
Amortized capitalized software costs	$ 1,300,000	1,100,000	700,000
Number of applications | application	1
Term of pilot phase, up to (in months)	6 months
Deferred costs, sales commissions, amortization period (in years)	5 years
Accrued liabilities, warranties	$ 0
Advertising expenses	15,800,000	6,900,000	51,900,000
401(k) matching contributions	$ 0	0	0
Number of operating segments | segment	1
Minimum
Subsidiary, Sale of Stock [Line Items]
Property and equipment, useful life (in years)	3 years
Minimum | Trials
Subsidiary, Sale of Stock [Line Items]
Revenue, performance obligation timing	56 days
Maximum
Subsidiary, Sale of Stock [Line Items]
Property and equipment, useful life (in years)	5 years
Maximum | Trials
Subsidiary, Sale of Stock [Line Items]
Revenue, performance obligation timing	112 days
C3.ai DTI Grants Program
Subsidiary, Sale of Stock [Line Items]
Contribution expense	$ 0	$ 0	$ 11,500,000