Number of additional shares reserved for issuance under an established employee stock purchase plan.

No definition available.

Name:	amba_AdditionalSharesReservedForIssuanceUnderEstablishedPurchasePlan
Namespace Prefix:	amba_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Annual increase in ordinary shares for available for future issuance.

+ References

No definition available.

+ Details

Name:	amba_AnnualIncreaseInOrdinarySharesForAvailableForFutureIssuance
Namespace Prefix:	amba_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Annual increase in shares for available for future issuance by percentage of the outstanding ordinary shares on the first day of such fiscal year.

+ References

No definition available.

+ Details

Name:	amba_AnnualIncreaseInSharesForAvailableForFutureIssuanceByPercentageOfOutstandingOrdinarySharesOnFirstDayOfSuchFiscalYear
Namespace Prefix:	amba_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum number of ordinary shares reserved for issuance.

+ References

No definition available.

+ Details

Name:	amba_MaximumNumberOfOrdinarySharesReservedForIssuance
Namespace Prefix:	amba_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Stock repurchase program authorization date.

+ References

No definition available.

+ Details

Name:	amba_StockRepurchaseProgramAuthorizationDate
Namespace Prefix:	amba_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Stock repurchase program, extended expiration date.

+ References

No definition available.

+ Details

Name:	amba_StockRepurchaseProgramExtendedExpirationDate
Namespace Prefix:	amba_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Stock repurchase program, extended expiration period.

+ References

No definition available.

+ Details

Name:	amba_StockRepurchaseProgramExtendedExpirationPeriod
Namespace Prefix:	amba_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ClassOfStockLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

+ References

+ Details

Name:	us-gaap_CommonStockSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow to reacquire common stock during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3291-108585

+ Details

Name:	us-gaap_PaymentsForRepurchaseOfCommonStock
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

+ Details

Name:	us-gaap_PreferredStockParOrStatedValuePerShare
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

+ References

+ Details

Name:	us-gaap_PreferredStockSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

+ References

+ Details

Name:	us-gaap_PreferredStockSharesIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

+ References

+ Details

Name:	us-gaap_PreferredStockSharesOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of additional shares authorized for issuance under share-based payment arrangement.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of stock repurchase plan authorized.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramAuthorizedAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Expiration date for the purchase of an entity's own shares under a stock repurchase plan, in the YYYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramExpirationDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount remaining of a stock repurchase plan authorized.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_StockRepurchasedDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PlanNameAxis=amba_TwoThousandTwelveEquityIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=amba_TwoThousandTwentyOneEquityIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=amba_AmendedAndRestatedTwoThousandTwelveEmployeeStockPurchasePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=us-gaap_ScenarioPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=amba_StockRepurchaseProgramFiftyMillionAuthorizationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Capital Stock - Additional Information (Detail) - USD ($)					1 Months Ended	2 Months Ended	3 Months Ended	9 Months Ended
	May 25, 2021	May 29, 2020	Mar. 16, 2020	May 29, 2019	Jun. 30, 2021	Jun. 30, 2021	Apr. 30, 2021	Oct. 31, 2021	Oct. 31, 2020	Jan. 31, 2021
Class Of Stock [Line Items]
Preference shares, shares authorized								20,000,000		20,000,000
Preference shares, par value								$ 0.00045		$ 0.00045
Preference shares, shares issued								0		0
Preference shares, shares outstanding								0		0
Ordinary shares, shares authorized								200,000,000		200,000,000
Stock repurchased during period, cash								$ 0	$ 1,000,000
2012 Equity Incentive Plan [Member]
Class Of Stock [Line Items]
Additional ordinary shares reserved for issuance						0	1,599,634
2021 Equity Incentive Plan [Member]
Class Of Stock [Line Items]
Additional ordinary shares reserved for issuance					1,350,000
Maximum number of ordinary shares reserved for issuance					6,834,208	6,834,208
Amended and Restated 2012 Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Additional ordinary shares reserved for issuance							444,343
Amended and Restated 2012 Employee Stock Purchase Plan [Member] \| Scenario, plan automatically increased by the lessor of [Member]
Class Of Stock [Line Items]
Annual increase in ordinary shares for available for future issuance							1,500,000
Annual shares increase for future issuance by percentage under 2012 employee stock purchase plan							1.25%
Stock Repurchase Program $50.0 Million Authorization [Member]
Class Of Stock [Line Items]
Stock repurchase program, authorization date				May 29, 2019
Stock repurchase program, expiration date				Jun. 30, 2020
Stock repurchased, shares			25,719					0
Stock repurchased during period, cash			$ 1,000,000.0
Stock repurchase program, extended expiration period	12 months	12 months
Stock repurchase program, extended expiration date	Jun. 30, 2022	Jun. 30, 2021
Amount available under stock repurchase program								$ 49,000,000.0
Stock Repurchase Program $50.0 Million Authorization [Member] \| Maximum [Member]
Class Of Stock [Line Items]
Amount authorized under stock repurchase program				$ 50,000,000.0