Stockholders' Equity - Narrative (Details)				1 Months Ended		3 Months Ended		9 Months Ended
	Jul. 17, 2024 USD ($) $ / shares shares	Mar. 22, 2024 USD ($)	Mar. 21, 2024 USD ($) shares $ / shares	Oct. 31, 2025 $ / shares shares	Feb. 29, 2024 USD ($) shares	Sep. 30, 2025 USD ($) $ / shares shares	Mar. 31, 2024 USD ($) $ / shares shares	Sep. 30, 2025 USD ($) vote $ / shares shares	Sep. 30, 2024 USD ($) shares	Apr. 04, 2025 USD ($)	Dec. 31, 2024 $ / shares shares	Jun. 30, 2024 shares	Mar. 20, 2024 USD ($) $ / shares shares	Dec. 31, 2023 shares	[1]	Dec. 31, 2020 $ / shares shares	Oct. 31, 2020 $ / shares
Temporary Equity [Line Items]
Temporary equity, shares authorized (in shares)													53,761,506
Temporary equity, par value (in dollars per share) | $ / shares													$ 0.001
Common stock, issued (in shares)						28,588,261		28,588,261			27,531,490
Common stock, outstanding (in shares)						28,588,261		28,588,261			27,518,439
Issuance of common stock to Graphite stockholders as a result of the Merger (in shares)			8,320,485
Sale of stock, number of shares issued (in shares)			15,409,102
Common stock, par value (in dollars per share) | $ / shares						$ 0.00001		$ 0.00001			$ 0.00001
Sale of stock, consideration received | $			$ 53,500,000
Vote per share of common stock | vote								1
Series A preferred stock warrants converted (in shares)			164,676
Reclassification of warrant liability to equity | $		$ 1,900,000					$ 1,918,000
December 2020 Warrants
Temporary Equity [Line Items]
Warrants exercised, number of shares (in shares)					470,000											470,000
Proceeds from warrant exercises | $					$ 100,000
Warrants exchanged at closing of Merger (in shares)			95,034
Warrants to purchase common stock
Temporary Equity [Line Items]
Exercise price (in dollars per share) | $ / shares			$ 10.64
PIPE Financing
Temporary Equity [Line Items]
Sale of stock, number of shares issued (in shares)	1,578,947		3,559,565
Common stock, par value (in dollars per share) | $ / shares	$ 0.00001						$ 0.00001
Sale of stock, price per share (in dollars per share) | $ / shares	$ 19.00
Sale of stock, consideration received | $	$ 30,000,000.0		$ 53,500,000
Net proceeds | $								$ 0	$ 79,598,000
Sales Agreement
Temporary Equity [Line Items]
Sale of stock, number of shares issued (in shares)						0		920,500
Sale of stock, price per share (in dollars per share) | $ / shares						$ 28.75		$ 28.75
Aggregate sale proceeds receivable | $										$ 150,000,000.0
Net proceeds | $								$ 26,100,000
Remaining capacity under agreement | $						$ 123,500,000		$ 123,500,000
Sales Agreement | Subsequent Event
Temporary Equity [Line Items]
Sale of stock, number of shares issued (in shares)				2,698,134
Sale of stock, price per share (in dollars per share) | $ / shares				$ 45.79
LENZ OpCo Preferred Stock Exchanged for Graphite Common Stock
Temporary Equity [Line Items]
Shares issued, conversion of convertible preferred stock (in shares)			10,705,829
Class B Convertible Common Stock Exchanged for Graphite Common Stock
Temporary Equity [Line Items]
Shares issued, conversion of convertible preferred stock (in shares)			554,843
Series A Convertible Preferred Stock
Temporary Equity [Line Items]
Temporary equity, shares issued (in shares)													21,977,282
Temporary equity, shares outstanding (in shares)							0		0			0	21,977,282	21,977,282
Liquidation preference | $													$ 47,300,000
Liquidation preference per share (in dollars per share) | $ / shares													$ 2.15
Conversion of convertible preferred stock (in shares)							21,977,282
Series A-1 Convertible Preferred Stock
Temporary Equity [Line Items]
Temporary equity, shares issued (in shares)													2,950,548
Temporary equity, shares outstanding (in shares)							0		0			0	2,950,548	2,950,548
Liquidation preference | $													$ 10,000,000.0
Liquidation preference per share (in dollars per share) | $ / shares													$ 3.3892
Conversion of convertible preferred stock (in shares)							2,950,548
Series B Convertible Preferred Stock
Temporary Equity [Line Items]
Temporary equity, shares issued (in shares)													28,019,181
Temporary equity, shares outstanding (in shares)													28,019,181
Liquidation preference | $													$ 83,500,000
Liquidation preference per share (in dollars per share) | $ / shares													$ 2.9801
Convertible Preferred Stock | LENZ OpCo Preferred Stock Exchanged for Graphite Common Stock
Temporary Equity [Line Items]
Conversion of convertible preferred stock (in shares)			52,947,011
Class A Common Stock
Temporary Equity [Line Items]
Common stock, issued (in shares)			11,838,624										11,838,624
Common stock, outstanding (in shares)			11,668,867										11,668,867
Class A Common Stock | December 2020 Warrants
Temporary Equity [Line Items]
Exercise price (in dollars per share) | $ / shares																$ 0.21
Class B convertible common stock
Temporary Equity [Line Items]
Temporary equity, shares issued (in shares)													2,744,184
Temporary equity, shares outstanding (in shares)													2,744,184
Common Stock
Temporary Equity [Line Items]
Common stock, issued (in shares)			2,393,729
Common stock, outstanding (in shares)			2,359,408
Series A Preferred Stock | October 2020 Warrants
Temporary Equity [Line Items]
Exercise price (in dollars per share) | $ / shares																	$ 2.15

[1] Retroactively recast for the reverse recapitalization as described in Note 3.