Common Stock - Equity Awards - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2025	Dec. 31, 2024
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for options currently outstanding	2,127,863	2,127,863	2,139,414
Number of shares granted		313,500
Unrecognized compensation expense related to stock options granted	$ 2.2	$ 2.2
Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period, restricted stock awards		1 year 8 months 26 days
Employee Stock Option [Member] \| Employees and Consultants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period		4 years
Employee Stock Option [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award expiration period		7 years
Employee Stock Option [Member] \| Minimum [Member] \| Board of Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period		1 year
Employee Stock Option [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award expiration period		10 years
Employee Stock Option [Member] \| Maximum [Member] \| Board of Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period		3 years
Restricted Stock Unit [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted shares reserved for issuance under incentive plan	2,569,350	2,569,350
Award vesting period		4 years
Weighted-average period, restricted stock awards		7 months 17 days
2018 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for issuance under incentive plan	320,637	320,637
Award expiration period		10 years
2018 Equity Incentive Plan [Member] \| Minimum [Member] \| Employees and Consultants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period		3 years
2018 Equity Incentive Plan [Member] \| Minimum [Member] \| Board of Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period		1 year
2018 Equity Incentive Plan [Member] \| Maximum [Member] \| Employees and Consultants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period		4 years
2018 Equity Incentive Plan [Member] \| Maximum [Member] \| Board of Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period		3 years
2018 Equity Incentive Plan [Member] \| Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for issuance under incentive plan	4,401,669	4,401,669
Common shares reserved for options currently outstanding	1,511,682	1,511,682
New Employee Inducement Grants [Member] \| Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for options currently outstanding	134,375	134,375
Award expiration period		10 years
Number of shares granted	0	0
2017 Equity Incentive Plan [Member] \| Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for issuance under incentive plan	10,536	10,536
2010 Performance Incentive Plan [Member] \| Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for issuance under incentive plan	20	20
2023 Non Employee Director Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for issuance under incentive plan	9,750	9,750
Award expiration period		10 years
2023 Non Employee Director Equity Incentive Plan [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period		1 year
2023 Non Employee Director Equity Incentive Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period		3 years
2023 Non Employee Director Equity Incentive Plan [Member] \| Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for issuance under incentive plan	300,000	300,000
Common shares reserved for options currently outstanding	290,250	290,250
2024 Equity Inducement Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for issuance under incentive plan	901,000	901,000
Award expiration period		10 years
2024 Equity Inducement Plan [Member] \| Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for issuance under incentive plan	1,250,000	1,250,000
Common shares reserved for options currently outstanding	181,000	181,000
2024 Equity Inducement Plan [Member] \| Restricted Stock Unit [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares reserved for options currently outstanding	168,000	168,000

ACHIEVE LIFE SCIENCES, INC. 10-Q