Earnings Per Common Share (Reconciliation Of Numerators And Denominators Of Basic And Diluted Earnings Per Share) (Details) - USD ($)	3 Months Ended	6 Months Ended
Mar. 25, 2017	Mar. 26, 2016	Mar. 25, 2017	Mar. 26, 2016
Class A Common Stock [Member]
Schedule Of Calculation Of Numerator And Denominator In Earnings Per Share [Line Items]
Net income allocated, basic	$ 6,513,698	$ 10,169,757	$ 16,328,364	$ 19,352,122
Conversion of Class B to Class A shares	2,637,749	4,188,654	6,646,970	7,985,712
Net income allocated, diluted	$ 9,151,447	$ 14,358,411	$ 22,975,334	$ 27,337,834
Weighted average shares outstanding, basic	14,038,094	13,942,826	14,002,300	13,934,874
Conversion of Class B to Class A shares	6,221,682	6,316,950	6,257,476	6,324,902
Weighted average shares outstanding, diluted	20,259,776	20,259,776	20,259,776	20,259,776
Earnings per share, Basic	$ 0.47	$ 0.73	$ 1.17	$ 1.39
Earnings per share, Diluted	$ 0.45	$ 0.71	$ 1.13	$ 1.35
Class B Common Stock [Member]
Schedule Of Calculation Of Numerator And Denominator In Earnings Per Share [Line Items]
Net income allocated, basic	$ 2,637,749	$ 4,188,654	$ 6,646,970	$ 7,985,712
Net income allocated, diluted	$ 2,637,749	$ 4,188,654	$ 6,646,970	$ 7,985,712
Weighted average shares outstanding, basic	6,221,682	6,316,950	6,257,476	6,324,902
Weighted average shares outstanding, diluted	6,221,682	6,316,950	6,257,476	6,324,902
Earnings per share, Basic	$ 0.42	$ 0.66	$ 1.06	$ 1.26
Earnings per share, Diluted	$ 0.42	$ 0.66	$ 1.06	$ 1.26

Schedule Of Calculation Of Numerator And Denominator In Earnings Per Share [Line Items]

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent, and includes adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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The aggregate value of preferred stock dividends and other adjustments necessary to derive net income apportioned to common stockholders.

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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