Share-based Compensation - Summary of The Unvested Common Stock (Detail) - Unvested Common Stock [Member]	6 Months Ended
	Jun. 30, 2025 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Shares, Unvested Common Stock, Beginning balance \| shares	82,281
Vested \| shares	(81,546)
Number of Shares, Forfeited \| shares	(735)
Number of Shares, Unvested Common Stock, Ending balance \| shares	0
Weighted Average Grant Date Fair Value Per Share, Beginning Balance \| $ / shares	$ 16
Vested \| $ / shares	16
Forfeiture \| $ / shares	16
Weighted Average Grant Date Fair Value Per Share, Ending Balance \| $ / shares	$ 0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Day One Biopharmaceuticals, Inc. 10-Q