Restructuring (Additional Information) (Details) $ in Thousands	12 Months Ended
Dec. 30, 2023 USD ($)
Restructuring Charges [Abstract]
Restructuring cost in operating expenses	$ 3,571
Restructuring cost in cost of goods sold	$ 7,027

Restructuring cost recored to cost of goods sold for inventory write-downs.

No definition available.

Name:	onto_RestructuringCostInCostOfGoodsSold
Namespace Prefix:	onto_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration