Defined Contribution Plan, Employee Contributions, Percentage of Eligible Compensation

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

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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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Share based compensation employee stock purchase plan contribution percentage.

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The number of share available for issuance.

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- Definition

Amount of cost for defined contribution plan.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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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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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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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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- Definition

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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- Definition

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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- Definition

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

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- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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- Definition

Gross number of share options (or share units) granted during the period.

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- Definition

Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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- Definition

Number of options outstanding, including both vested and non-vested options.

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- Definition

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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- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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- Definition

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

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- Definition

The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

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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, $ in Thousands	12 Months Ended
	Jan. 01, 2022 USD ($) Tradingday $ / shares shares	Dec. 26, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options expiration period	1 year
Shares purchased under ESPP	242,000	91,000	72,000
Employee stock purchase plan available	1,258,000	1,500,000
Number of trading days for closing stock price performance or market price performance \| Tradingday	20
Number of shares outstanding	765,000
Stock options granted	0	0	0
Total intrinsic value of stock options exercised \| $	$ 1,365	$ 420	$ 51
Aggregate intrinsic value \| $	191
Total intrinsic value of stock options exercisable \| $	$ 191
Stock options outstanding number	2,000
Stock options weighted average exercise price \| $ / shares	$ 15.20
Percentage of contribution for annual compensation	100.00%
Percentage of match of all employee contribution	50.00%
Total matching contribution to plan \| $	$ 2,544	$ 2,315	$ 1,317
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
Total unrecognized compensation cost related to restricted stock units granted \| $	$ 21,019
Unrecognized compensation cost related to restricted stock units, weighted average period	1 year 6 months
Number of shares outstanding	667,000
Performance Restricted Stock Units (PRSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Period of vesting	3 years
Number of shares outstanding	98,000
Weighted average grant-date fair value per share \| $ / shares	$ 80.04	$ 47.86	$ 21.49
Onto Innovation 2020 Stock Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share authorized available for grants	3,744,000
Period of vesting	3 years
Options expiration period	10 years
Shares of common stock available for issuance pursuant to future grants	3,376,000
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