Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 26, 2018	Sep. 27, 2017	Sep. 26, 2018	Sep. 27, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, options outstanding (shares)	2,130,802		2,130,802
Common stock, options vested (shares)			1,741,217
Common stock, options unvested (shares)	389,585		389,585
Stock options exercised (shares)	249,091	0	249,091	17,661
Number of options granted at fair market value (shares)	190,520	0	311,272	128,252
Incremental stock-based compensation expense			$ 800
Stock-based compensation	$ 400	$ 300	$ 1,547	$ 738
Premium Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, options outstanding (shares)	1,392,785		1,392,785
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense	$ 1,400		$ 1,400
Unrecognized compensation expense, period for recognition			3 years 6 months 7 days
Accelerated vesting of awards (shares)			33,545
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense, period for recognition			3 years 3 months
Shares granted (shares)	211,060	1,248	211,060	170,924
Unvested restricted shares outstanding (shares)	316,012		316,012
Unrecognized compensation expense	$ 3,500		$ 3,500
Performance Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense, period for recognition			4 years 7 months 13 days
Shares granted (shares)	0	0	72,116	0
Unvested restricted shares outstanding (shares)	72,116		72,116
Unrecognized compensation expense	$ 400		$ 400
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense, period for recognition			3 years 7 months 13 days
Shares granted (shares)	0	0	96,156	0
Unvested restricted shares outstanding (shares)	96,156		96,156
Unrecognized compensation expense	$ 900		$ 900

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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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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

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

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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 compensation cost was accelerated.

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Number of non-vested options outstanding.

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Number of options vested.

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

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