Name:	axsm_DebtInstrumentInterestOnlyPaymentsTerm
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Data Type:	xbrli:durationItemType
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Represents the number of loan tranches pertaining to the debt instrument.

No definition available.

Name:	axsm_DebtInstrumentNumberOfLoanTranches
Namespace Prefix:	axsm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The period of time during which prepayment premium condition one is in effect, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	axsm_DebtInstrumentPrepaymentPremiumConditionOneTerm
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Data Type:	xbrli:durationItemType
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Period Type:	duration

Represents the prepayment premium due, as a percent of the outstanding principal, if prepayment occurs under condition one.

No definition available.

Name:	axsm_DebtInstrumentPrepaymentPremiumPercentOfOustandingPrincipalConditionOne
Namespace Prefix:	axsm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Represents the prepayment premium due, as a percent of the outstanding principal, if prepayment occurs under condition three.

No definition available.

Name:	axsm_DebtInstrumentPrepaymentPremiumPercentOfOustandingPrincipalConditionThree
Namespace Prefix:	axsm_
Data Type:	num:percentItemType
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Period Type:	instant

Represents the prepayment premium due, as a percent of the outstanding principal, if prepayment occurs under condition two.

No definition available.

Name:	axsm_DebtInstrumentPrepaymentPremiumPercentOfOustandingPrincipalConditionTwo
Namespace Prefix:	axsm_
Data Type:	num:percentItemType
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Period Type:	instant

The percent of principal due, as a final payment fee, at extinguishment of debt.

No definition available.

Name:	axsm_ExtinguishmentOfDebtFeePercentOfPrincipal
Namespace Prefix:	axsm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Amount of noncash expense included in interest expense to issue debt and obtain financing associated with the related debt instruments. Alternate captions include noncash interest expense.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 8
-Article 9

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Name:	us-gaap_DebtInstrumentFaceAmount
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph 8
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Name:	us-gaap_InterestExpenseDebtExcludingAmortization
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Name:	us-gaap_DebtInstrumentAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DebtInstrumentAxis=axsm_LineOfCreditTermLoanTrancheOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DebtInstrumentAxis=axsm_LineOfCreditTermLoanTranchesTwoAndThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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Namespace Prefix:
Data Type:	na
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