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

Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015
Assets
Total assets	$ 40,559us-gaap_AssetsFairValueDisclosure
Warrant [Member]
Liabilities
Liabilities	2,537
Cash [Member]
Assets
Total assets	11,225
Money market securities [Member]
Assets
Total assets	14,053
Restricted cash [Member]
Assets
Total assets	190
Corporate bonds and commercial paper [Member]
Assets
Total assets	15,091
Level 1 [Member]
Assets
Total assets	25,468
Level 1 [Member] \| Cash [Member]
Assets
Total assets	11,225
Level 1 [Member] \| Money market securities [Member]
Assets
Total assets	14,053
Level 1 [Member] \| Restricted cash [Member]
Assets
Total assets	190
Level 2 [Member]
Assets
Total assets	15,091
Level 2 [Member] \| Corporate bonds and commercial paper [Member]
Assets
Total assets	15,091
Level 3 [Member] \| Warrant [Member]
Liabilities
Liabilities	$ 2,537