Stock-Based Compensation - Summary of Stock-based Compensation Expenses for Stock Options and Unvested Common Stock (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 144,715	$ 100,258	$ 275,792	$ 134,424
Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	15,297	1,815	32,112	2,878
Location, Statement of Income, Balance [Axis]: us-gaap:GeneralAndAdministrativeExpense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	47,050	15,547	91,389	25,989
Location, Statement of Income, Balance [Axis]: us-gaap:ResearchAndDevelopmentExpense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	63,618	76,234	116,319	93,626
Location, Statement of Income, Balance [Axis]: us-gaap:SellingAndMarketingExpense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	15,880	5,572	30,542	9,928
Location, Statement of Income, Balance [Axis]: ionq:CapitalizedStockBasedCompensationPropertyAndEquipmentNetAndIntangibleAssetsNet
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	2,870	1,090	5,430	2,003
Location, Statement of Income, Balance [Axis]: ionq:StockBasedCompensationNetOfAmountsCapitalized
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 141,845	$ 99,168	$ 270,362	$ 132,421