Description of Business and Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
Jul. 29, 2016	Jul. 31, 2015
Accounting Policies [Abstract]
Provision for income taxes	$ 28	$ 8
Accounting Standards Update 2016-09
Accounting Policies [Abstract]
Provision for income taxes	13
Accounting Standards Update 2016-09 \| Account for Forfeitures As Occur
Accounting Policies [Abstract]
Cumulative-effect impact to retained earnings	7
Accounting Standards Update 2016-09 \| Forfeiture Rate Policy Change On Outstanding Stock Based Awards
Accounting Policies [Abstract]
Cumulative-effect adjustment to retained earnings	(3)
Accounting Standards Update 2016-09 \| Previously Unrecognized Tax Benefits
Accounting Policies [Abstract]
Cumulative-effect adjustment to retained earnings	$ 17

No definition available.

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

- Definition

Amount of the cumulative effect on retained earnings before related income tax effect.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=64853466&loc=d3e22663-107794

+ Details

Name:	us-gaap_CumulativeEffectOnRetainedEarningsBeforeTax1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of the related income tax effect of a cumulative effect on retained earnings.

+ References

+ Details

Name:	us-gaap_CumulativeEffectOnRetainedEarningsTax1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a),(b)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32639-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Income Tax Expense (or Benefit)
-URI http://asc.fasb.org/extlink&oid=6515339

+ Details

Name:	us-gaap_IncomeTaxExpenseBenefit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=ntap_AccountingStandardsUpdate201609Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis=ntap_AccountForForfeituresAsOccurMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis=ntap_ForfeitureRatePolicyChangeOnOutstandingStockBasedAwardsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis=ntap_PreviouslyUnrecognizedTaxBenefitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: