Summary of Business and Significant Accounting Policies (Details)	1 Months Ended		12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares	Nov. 30, 2020 shares	Apr. 30, 2023 USD ($) segment application shares	Apr. 30, 2022 USD ($) shares	Apr. 30, 2021 USD ($)
Subsidiary, Sale of Stock [Line Items]
Reverse stock split ratio, common stock		0.1667
Deferred offering costs reclassified into stockholders' equity as a reduction of the IPO proceeds	$ 7,200,000
Restricted cash			$ 12,600,000	$ 12,600,000
Allowance for doubtful accounts			400,000	200,000
Unbilled receivables			77,600,000	19,900,000
Long-lived assets, impairment			0	0	$ 0
Goodwill, impairment			0	0	0
Capitalized software costs			3,000,000	3,000,000	0
Amortized capitalized software costs			$ 1,100,000	700,000
Term of pilot phase			6 months
Number of applications | application			1
Deferred costs, sales commissions, amortization period (in years)			5 years
Accrued liabilities, warranties			$ 0
Advertising expenses			6,900,000	51,900,000	35,300,000
401(k) matching contributions			$ 0	0	0
Number of operating segments | segment			1
Pilot Phase, Commitment Term Component One
Subsidiary, Sale of Stock [Line Items]
Term of pilot phase			1 year
Pilot Phase, Commitment Term Component Two
Subsidiary, Sale of Stock [Line Items]
Term of pilot phase			2 years
Pilot Phase, Commitment Term Component Three
Subsidiary, Sale of Stock [Line Items]
Term of pilot phase			3 years
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	$ 11,500,000	$ 2,700,000
IPO
Subsidiary, Sale of Stock [Line Items]
Net proceeds received	694,600,000
Private Placement
Subsidiary, Sale of Stock [Line Items]
Net proceeds received	$ 150,000,000
Class A Common Stock
Subsidiary, Sale of Stock [Line Items]
Common stock, shares authorized (in shares) | shares		390,000,000	1,000,000,000	1,000,000,000
Class A Common Stock | IPO
Subsidiary, Sale of Stock [Line Items]
Sale of stock, number of shares issued (in shares) | shares	17,825,000
Sale of stock, shares issued, price per share (in dollars per share) | $ / shares	$ 42.00
Class A Common Stock | Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Sale of stock, number of shares issued (in shares) | shares	2,325,000
Class A Common Stock | Private Placement
Subsidiary, Sale of Stock [Line Items]
Sale of stock, shares issued, price per share (in dollars per share) | $ / shares	$ 42.00
Class A Common Stock | Private Placement | Spring Creek Capital LLC
Subsidiary, Sale of Stock [Line Items]
Sale of stock, number of shares issued (in shares) | shares	2,380,952
Class A Common Stock | Private Placement | Microsoft Corporation
Subsidiary, Sale of Stock [Line Items]
Sale of stock, number of shares issued (in shares) | shares	1,190,476
Redeemable Convertible Class A-1 Common Stock
Subsidiary, Sale of Stock [Line Items]
Shares authorized (in shares) | shares		6,666,667
Conversion of stock, converted (in shares) | shares	6,666,665
Conversion ratio	1
Class B Common Stock
Subsidiary, Sale of Stock [Line Items]
Common stock, shares authorized (in shares) | shares		21,000,000	3,500,000	3,500,000
Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Shares authorized (in shares) | shares		233,107,379
Redeemable Convertible Preferred Stock, Excluding Series A Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, converted (in shares) | shares	33,628,776
Conversion ratio	1
Series A Redeemable Convertible Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, converted (in shares) | shares	3,499,992
Conversion ratio	1