Net Income per Share - Additional Information (Detail)	3 Months Ended
Mar. 26, 2016 Employee shares	Mar. 28, 2015 shares
Earnings Per Share Disclosure [Line Items]
Performance Based Stock Options Cancelled During the Period	14,742
Investment Share Program
Earnings Per Share Disclosure [Line Items]
Requirement tenure of employee for investment share program, purchase shares at discount	2 years
Vesting period	5 years
Investment Share Program \| Minimum
Earnings Per Share Disclosure [Line Items]
Requirement tenure of employee for investment share program	1 year
Discount from current market value	20.00%
Investment Share Program \| Maximum
Earnings Per Share Disclosure [Line Items]
Discount from current market value	40.00%
Common Class A
Earnings Per Share Disclosure [Line Items]
Antidilutive securities excluded from computation of earnings per share	656,000	4,000
Common Class A \| Performance-Based Awards
Earnings Per Share Disclosure [Line Items]
Number of shares not included because the performance criteria was not met as of the end of the reporting period	18,000	45,000
Common Class A \| Performance-Based Awards \| Key Employee
Earnings Per Share Disclosure [Line Items]
Options granted in period	10,000
Number of employees \| Employee	1
Common Class A \| Performance-Based Awards \| Executive Officers
Earnings Per Share Disclosure [Line Items]
Options granted in period	8,000

Earnings Per Share Disclosure [Line Items]

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Number of Employees

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Antidilution
-URI http://asc.fasb.org/extlink&oid=6505113

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Diluted Earnings Per Share
-URI http://asc.fasb.org/extlink&oid=6510752

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Contingent Stock Agreement
-URI http://asc.fasb.org/extlink&oid=6508534

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Discount rate from fair value on purchase date that participants pay for shares.

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-Topic 718
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- Definition

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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

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The addition or reduction in the number of reserved shares that could potentially be issued under the option plan attributable to reasons other than grants, exercises, forfeitures, and expirations during the reporting period.

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