XML 46 R33.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] $ in Thousands | Sep. 30, 2018 USD ($)
--- | ---
Assets |
Total assets | $ 13,195
Cash [Member] |
Assets |
Total assets | 2,936
Money market securities (cash equivalents) [Member] |
Assets |
Total assets | 8,819
Restricted cash [Member] |
Assets |
Total assets | 50
Corporate bonds and commercial paper (short term investments) [Member] |
Assets |
Total assets | 1,390
Level 1 [Member] |
Assets |
Total assets | 11,805
Level 1 [Member] | Cash [Member] |
Assets |
Total assets | 2,936
Level 1 [Member] | Money market securities (cash equivalents) [Member] |
Assets |
Total assets | 8,819
Level 1 [Member] | Restricted cash [Member] |
Assets |
Total assets | 50
Level 2 [Member] |
Assets |
Total assets | 1,390
Level 2 [Member] | Corporate bonds and commercial paper (short term investments) [Member] |
Assets |
Total assets | $ 1,390

X
- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
Name: | us-gaap_AssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_AssetsFairValueDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_CashMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=achv_RestrictedCashMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |