Schedule of Changes in Outstanding Common Shares and Treasury Stock (Detail) - shares	12 Months Ended
Sep. 28, 2018	Sep. 29, 2017
Equity [Abstract]
Shares issued, beginning of year	33,117,473
Shares issued under share-based compensation plans	72,994	553,221
Shares issued, end of year	33,190,467	33,117,473
Treasury stock purchased, beginning of year	(3,135,927)
Treasury stock purchased	(601,400)	0
Treasury stock purchased, end of year	(3,737,327)	(3,135,927)
Shares outstanding, end of year	29,453,140	29,981,546

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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- Definition

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Gross number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP). Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

+ References

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- Definition

Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29,30)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

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Number of shares that have been repurchased during the period and are being held in treasury.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Name Accounting Standards Codification
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