Achieve Life Sciences, Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Common Stock - Issued and Outstanding Shares - Additional Information (Detail)

Common Stock - Issued and Outstanding Shares - Additional Information (Detail) - USD ($)								1 Months Ended	3 Months Ended				4 Months Ended	9 Months Ended		37 Months Ended
	Aug. 03, 2020	Jul. 01, 2020	Apr. 28, 2020	Dec. 17, 2019	May 30, 2019	May 22, 2018	Sep. 14, 2017	Mar. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Mar. 31, 2019	Oct. 20, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019	Jun. 07, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, par value									$ 0.001					$ 0.001		$ 0.001	$ 0.001
Common stock, shares issued									3,616,414					3,616,414		3,616,414	1,474,258
Preferred stock, par value									$ 0.001					$ 0.001		$ 0.001
Proceeds from exercise of warrants, net of issuance costs					$ 4,200,000									$ 3,080,000	$ 4,199,000
Stock option exercises, Shares									0		0			0	0
Restricted stock unit settlements									236		256			236	256
Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock unit settlements									128		250	4
December 2019 Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price per unit of warrant				$ 6.60
Offering expenses														$ 34,000
Warrant exercisable period				5 years
Cancellation of warrant description														Additionally, subject to certain exceptions, if, after December 17, 2019, (i) the volume weighted average price of the common stock for each of 30 consecutive trading days, or the 2019 Measurement Period, which 2019 Measurement Period commences on the closing date, exceeds 300% of the exercise price (subject to adjustments for stock splits, recapitalizations, stock dividends and similar transactions), (ii) the average daily trading volume for such 2019 Measurement Period exceeds $500,000 per trading day and (iii) certain other equity conditions are met, and subject to a beneficial ownership limitation, then the Company may call for cancellation of all or any portion of the warrants then outstanding.
Number of required consecutive days weighted average trading price for cancelation or recall of warrants				30 days
Minimum required trading price percentage over exercise price for cancelation or recall of warrants				300.00%
Minimum required trading volume value per day for cancelation or recall of warrants				$ 500,000
Gross proceeds from sale of warrants and units														$ 13,800,000
Warrant and units offering cost including underwriting discounts and commissions														1,500,000
Net proceeds from issuance of warrants and units														$ 12,300,000
April 2020 Private Placement [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares issued			280,782
Warrants to purchase shares of common stock			0.75
Warrants to purchase shares of common stock, offering price per share			$ 6.60
Gross proceeds from issuance of common stock			$ 1,900,000
Proceeds from exercise of warrants, net of issuance costs			$ 1,600,000
Percentage of exercise price exceeds in measurement period														300.00%
Average daily trading volume for measurement period														$ 500,000
April 2020 Private Placement [Member] \| Placement Agent [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price per unit of warrant			$ 7.59
Warrants to purchase common stock			25,270
Percentage of cash commission in gross proceeds from sale of units			9.00%
April 2020 Private Placement [Member] \| Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares issued										280,782
Direct Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Gross proceeds from issuance of common stock		$ 6,000,000
Aggregate percentage of gross proceeds paid as cash fee for placement agent and advisor		8.00%
Placement agent fees and offering expenses		$ 700,000
Proceeds from issuance of common stock		$ 5,300,000
Direct Offering [Member] \| Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares issued		731,707							731,707
Common stock, price per share		$ 8.20
August 2020 Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Gross proceeds from issuance of common stock	$ 7,500,000
Proceeds from issuance of common stock	6,800,000													$ 6,822,000
Underwriting discounts and commissions and offering expenses	$ 700,000
August 2020 Public Offering [Member] \| Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares issued	569,043								569,043
Common stock, price per share	$ 10.50
Underwriters Over-Allotment Option Exercise [Member] \| Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares issued	92,856
Series A Convertible Preferred Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Preferred stock, par value									$ 0.001					$ 0.001		$ 0.001	$ 0.001
Preferred stock, shares outstanding									0					0		0	0
Series B Convertible Preferred Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Preferred stock, par value									$ 0.001					$ 0.001		$ 0.001	$ 0.001
Preferred stock, shares outstanding									0					0		0	1,121
Series B Convertible Preferred Stock [Member] \| December 2019 Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Preferred stock, shares converted														6,256
Preferred stock, shares outstanding									0					0		0
Series B Convertible Preferred Stock [Member] \| December 2019 Public Offering [Member] \| Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Convertible preferred stock, shares issued upon conversion														521,124
Maximum [Member] \| December 2019 Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price per unit of warrant				$ 1.20
Subscription Agreements Executed on April 27, 2020 [Member] \| April 2020 Private Placement [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price per unit of warrant									$ 7.24					$ 7.24		$ 7.24
Subscription Agreements Executed on April 28, 2020 [Member] \| April 2020 Private Placement [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price per unit of warrant									$ 7.32					$ 7.32		$ 7.32
Class A Units [Member] \| December 2019 Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of new units in a public offering				478,875
Public offering, price per unit				$ 12.00
Description of stock units issued														Each Class A Unit consisted of one share of our common stock and a warrant to purchase one share of common stock.
Class B Units [Member] \| December 2019 Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of new units in a public offering				6,256
Public offering, price per unit				$ 999.60
Description of stock units issued														Each Class B Unit consisted of one share of Series B Convertible Preferred Stock, par value $0.001 per share, convertible at any time at the holder’s option into approximately 83 shares of common stock, and warrants to purchase approximately 83 shares of common stock.
Number of common shares issuable for each share of convertible preferred stock				83
Warrants to purchase common stock				83
Class B Units [Member] \| Series A Convertible Preferred Stock [Member] \| December 2019 Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Preferred stock, par value				$ 0.001
Pre-Funded Warrant [Member] \| August 2020 Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants to purchase common stock	142,857
Pre-funded warrant, offering price per share	$ 10.499
Pre-Funded Warrant [Member] \| August 2020 Public Offering [Member] \| Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price per unit of warrant	$ 0.001
Number of days of prior notice to achieve not in excess percentage of common stock shares owned by warrant holder	61 days
Pre-Funded Warrant [Member] \| Maximum [Member] \| August 2020 Public Offering [Member] \| Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of shares of common stock owned by warrant holder	19.99%
Pre-Funded Warrant [Member] \| Minimum [Member] \| August 2020 Public Offering [Member] \| Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of shares of common stock owned by warrant holder	9.99%
LPC [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock value right to sell, maximum							$ 11,000,000
Common stock, par value							$ 0.001
Minimum percentage of common stock shares outstanding authorized to sell						20.00%
Initial purchase of common stock																1,644
Common stock, shares issued							617
Payments related to expense reimbursement								$ 100,000
Common stock, shares issued									0					0		27,868
Gross proceeds																$ 4,400,000
Offering expenses																500,000
Common stock available for sale under offering									$ 6,600,000					$ 6,600,000		$ 6,600,000
LPC [Member] \| Purchase Agreement [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, purchase price							$ 1.00
Additional common stock value right to sell, maximum							$ 10,000,000
Additional purchase of common stock, maximum							7,500
Offering expenses														$ 14,000
LPC [Member] \| Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Initial purchase of common stock							1,644
Common stock, purchase price							$ 608.00
Purchase agreement, description														Unit consisting of (a) one share of our common stock and (b) one warrant to purchase one-quarter of a share of common stock at an exercise price of $699.20 per share, or Warrant. Each Warrant became exercisable six months following the issuance date until the date that is five years and six months after the issuance date and is subject to customary adjustments.
Exercise price per unit of warrant							$ 699.20
Initial purchase of units consisting of common stock and warrants issued							$ 1,000,000
LPC [Member] \| Other Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of warrants issued							0
H.C. Wainwright [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, par value																		$ 0.001
H.C. Wainwright [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock value right to sell, maximum																		$ 6,000,000
H.C. Wainwright [Member] \| Subsequent Event [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares issued													0
Ladenburg Thalmann & Co. Inc [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Period granted for underwriting option				45 days
Ladenburg Thalmann & Co. Inc [Member] \| 2019 Overallotment Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional purchase of common stock and warrants, maximum				150,000
Overallotment option exercise date				Dec. 17, 2019