Balance Sheet Components (Schedule of Other Accrued Liabilities) (Parentheticals) (Details) - USD ($) $ in Millions	Sep. 27, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Inventory expected to be received from future sales returns	$ 30.7	$ 26.8
Provisions to write down expected returned inventory to net realizable value	$ 16.6	$ 14.9

Provisions to write down expected returned inventory to net realizable value.

No definition available.

Name:	ntgr_ProvisionsToWriteDownExpectedReturnedInventoryToNetRealizableValue
Namespace Prefix:	ntgr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant