Date of plan approval.

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Maximum grant period from date of plan approval.

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Represents the compensation cost capitalized during the period arising from equity-based compensation arrangements (for example, shares of stock, units, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of cash inflow from realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

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Amount of cash inflow from exercise of stock options granted under share-based compensation arrangement.

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The noncash expense that represents the cost of restricted stock or unit distributed to employees as compensation.

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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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No definition available.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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

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No definition available.

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Amount of capitalized and expensed compensation cost from equity-based compensation arrangements.

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

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Number of share options (or share units) exercised during the current period.

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The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation.

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Stock-Based Compensation - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	May 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized number of common stock shares for grant	1,200,000
Date of plan approval	May 16, 2018
Maximum grant period from date of plan approval	10 years
Shares available for grant under the plan	1,184,305
Compensation cost related to restricted stock	$ 2,500,000	$ 2,100,000
Compensation cost related to stock options	$ 400,000	200,000
Stock options granted	69,014
Stock options exercised	4,000
Cash received from stock option exercises under the plan	$ 0	100,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized number of common stock shares for grant			1,000,000
Number of shares purchased	7,382
Compensation cost	$ 200,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to non-vested stock options	$ 5,200,000
Unrecognized compensation cost related to nonvested stock options, weighted-average period	2 years 3 months 18 days
Tax benefit generated from compensation cost and credited		300,000
Restricted Stock [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Tax benefit generated from compensation cost and credited	$ 100,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to non-vested stock options	$ 1,600,000
Unrecognized compensation cost related to nonvested stock options, weighted-average period	2 years 10 months 24 days
Tax benefit generated from compensation cost and credited	$ 0	600,000
Capitalized compensation cost	$ 0	$ 0
Stock options granted	69,014	58,024
Stock options exercised	4,000	32,000