Disclosure - Restructuring (Additional Information) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 29, 2024	Jul. 01, 2023	Jun. 29, 2024	Jul. 01, 2023
Restructuring Charges [Abstract]
Restructuring cost in cost of goods sold	$ 703	$ 0	$ 1,491	$ 2,279
RestructuringCost	1,324	1,192	2,370	5,505
Restructuring costs in operating expenses	$ 621	$ 1,192	$ 879	$ 3,226

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