Business Combinations (Acquisition-Related Expenses) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Apr. 27, 2012	Apr. 29, 2011	Apr. 30, 2010
Business Combinations [Abstract]
Acquisition-related expense (income), net	$ 9.8	$ 5.7	$ (39.9)

Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, advisory, legal, accounting, valuation, and other professional or consulting fees. This element also includes proceeds received as a result of a terminated acquisition.

No definition available.

Name:	ntap_BusinessCombinationIntegrationAndAcquisitionRelatedCostsOrAcquisitionTerminationProceedsNetOfExpenses
Namespace Prefix:	ntap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration