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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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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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Net number of non-option equity instruments granted to participants.

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

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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

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

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An excess of the fair value of the modified award over the fair value of the award immediately before the modification.

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Number of shares for which recognition of cost was accelerated for award 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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Expected term of 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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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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Number of non-vested options outstanding.

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Number of options vested.

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Amount of noncash expense for option under share-based payment arrangement.

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Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 30, 2020	Dec. 25, 2019	Dec. 26, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized number of common stock for issuance (shares)	5,652,240
Number of share available for grant (shares)	803,527
Stock-based compensation expense	$ 3,100	$ 2,500	$ 2,000
Common stock, options outstanding (shares)	1,030,866	2,077,570	2,102,404
Common stock, options vested (shares)	685,007
Common stock, options unvested (shares)	345,859
Options to purchase common stock granted (shares)		323,900
Options expiration period	10 years
Aggregate intrinsic value of options outstanding	$ 8,638
Aggregate intrinsic value of options exercisable	6,288
Intrinsic value of options exercised	9,900	$ 2,100	$ 1,500
Weighted average grant date fair value (usd per share)		$ 3.85	$ 3.78
Unrecognized compensation expense	$ 1,000
Unrecognized compensation expense, recognition period	1 year 11 months 26 days
Granted (shares)	415,022	299,052
Unvested restricted shares outstanding (shares)	742,404	588,008	490,700
Former President and CEO
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accelerated vesting of awards (shares)			33,545
Incremental expense from plan modification			$ 800
Exercise price equal to the fair market value of the common stock on the date of grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase common stock granted (shares)		323,900
Option vesting period		4 years
Premium Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, options outstanding (shares)	303,786
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility		28.70%	28.40%
Risk-free interest rate		2.30%	2.90%
Expected life		6 years 3 months	6 years 3 months
Expected dividend yield	0.00%	0.00%	0.00%
Restricted Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, recognition period	2 years 9 months 7 days
Granted (shares)	415,022	299,052
Unvested restricted shares outstanding (shares)	658,268
Unrecognized compensation expense	$ 6,300
Restricted Shares \| Nonemployee Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period	3 years
Restricted Shares \| Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period	4 years
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, recognition period	2 years 4 months 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted			72,116
Unvested restricted shares outstanding (shares)	36,058
Unrecognized compensation expense	$ 100
Performance Shares \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period			1 year
Performance Shares \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period			5 years
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 300
Unrecognized compensation expense, recognition period	1 year 4 months 6 days
Unvested restricted shares outstanding (shares)	48,078