Accumulated Other Comprehensive Income (Loss) - Additional Information (Details) $ in Thousands	9 Months Ended
Oct. 01, 2022 USD ($)
Accumulated Other Comprehensive Loss [Abstract]
Tax Effect Marketable Securities	$ 962
Tax Effect Foreign Currency Translation	$ 0

tax effects on net income of amounts recorded in other comprehensive loss for net unrealized losses on available-for-sale marketable securities.

No definition available.

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