Other Long-Term Liabilities - Additional Information (Detail) - Accounting Standards Update (ASU) 2016-09 [Member] $ in Millions	Feb. 01, 2016 USD ($)
Other Liabilities Noncurrent [Line Items]
Cumulative effect adjustment of changes recognized in beginning of retained earnings as a result of adoption of new guidance for tax benefits that were not previously recognized	$ 11.7
Unrecognized tax benefits reduced as a result of adoption of new accounting guidance	$ 9.5

Cumulative effect adjustment of changes recognized in beginning of retained earnings as a result of adoption of new guidance for tax benefits that were not previously recognized.

No definition available.

Name:	amba_CumulativeEffectAdjustmentOfChangesRecognizedInBeginningOfRetainedEarningsAsAResultOfAdoptionOfNewGuidanceForTaxBenefitsThatWereNotPreviouslyRecognized
Namespace Prefix:	amba_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant