Defined Contribution Plan, Employee Contributions, Percentage of Eligible Compensation

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- Definition

Number of shares available to issuance under the employee stock purchase plan.

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- Definition

Number of trading days for closing stock price performance or market price performance.

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Percentage of common Stock price performance compared to market price performance designated as bench mark.

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- Definition

Share based compensation employee stock purchase plan contribution percentage.

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- Definition

The number of share available for issuance.

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- Definition

Amount of cost for defined contribution plan.

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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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- Definition

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

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- Definition

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of shares authorized for issuance under share-based payment arrangement.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Purchase price of common stock expressed as a percentage of its fair value.

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No definition available.

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- Definition

Number of shares issued during the period as a result of an employee stock purchase plan.

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Share-Based Compensation and Employee Benefit Plans - Textual (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 30, 2023 USD ($) Tradingday $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Jan. 01, 2022 USD ($) $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock available for issuance pursuant to future grants	2,868
Shares purchased under ESPP	91	142	242
Employee stock purchase plan available	1,025	1,116
Number of trading days for closing stock price performance or market price performance \| Tradingday	20
Total unrecognized compensation cost related to restricted stock units granted \| $	$ 26,559
Unrecognized compensation cost related to restricted stock units, weighted average period	1 year 4 months 24 days
Weighted average grant-date fair value per share \| $ / shares	$ 85.41	$ 69.01
Percentage of contribution for annual compensation	100.00%
Percentage of match of all employee contribution	50.00%
Total matching contribution to plan \| $	$ 3,128	$ 2,965	$ 2,544
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of common Stock price performance compared to market price performance designated as bench mark	200.00%
Percentage of match on employee salary	6.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of common Stock price performance compared to market price performance designated as bench mark	0.00%
Onto Innovation 2020 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Price of common stock as percentage of fair market value	85.00%
Onto Innovation 2020 Employee Stock Purchase Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Eligible compensation deduction percentage on pay for purchase of common stock	10.00%
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Period of vesting	3 years
Performance Restricted Stock Units (PRSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Period of vesting	3 years
Weighted average grant-date fair value per share \| $ / shares	$ 100.79	$ 85.49	$ 80.04
Onto Innovation 2020 Stock Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share authorized available for grants	3,744
Period of vesting	3 years
Options expiration period	10 years
Onto Innovation 2020 Stock Plan [Member] \| Restricted Stock Units (RSUs) [Member] \| Employees [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Period of vesting	3 years
Onto Innovation 2020 Stock Plan [Member] \| Restricted Stock Units (RSUs) [Member] \| Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Period of vesting	1 year