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. 30, 2019	Mar. 31, 2018	Mar. 30, 2019	Mar. 31, 2018
Class A Common Stock [Member]
Schedule Of Calculation Of Numerator And Denominator In Earnings Per Share [Line Items]
Net income (loss) allocated, basic	$ 10,773,567	$ 6,661,301	$ 26,678,194	$ 38,993,337
Conversion of Class B to Class A shares	4,226,473	2,633,487	10,474,183	15,448,190
Net income (loss) allocated, diluted	$ 15,000,040	$ 9,294,788	$ 37,152,377	$ 54,441,527
Weighted average shares outstanding, basic	14,154,424	14,120,232	14,149,904	14,111,787
Conversion of Class B to Class A shares	6,105,352	6,139,544	6,109,872	6,147,989
Weighted average shares outstanding, diluted	20,259,776	20,259,776	20,259,776	20,259,776
Earnings (loss) per share, Basic	$ 0.76	$ 0.47	$ 1.88	$ 2.76
Earnings (loss) per share, Diluted	$ 0.74	$ 0.46	$ 1.83	$ 2.69
Class B Common Stock [Member]
Schedule Of Calculation Of Numerator And Denominator In Earnings Per Share [Line Items]
Net income (loss) allocated, basic	$ 4,226,473	$ 2,633,487	$ 10,474,183	$ 15,448,190
Net income (loss) allocated, diluted	$ 4,226,473	$ 2,633,487	$ 10,474,183	$ 15,448,190
Weighted average shares outstanding, basic	6,105,352	6,139,544	6,109,872	6,147,989
Weighted average shares outstanding, diluted	6,105,352	6,139,544	6,109,872	6,147,989
Earnings (loss) per share, Basic	$ 0.69	$ 0.43	$ 1.71	$ 2.51
Earnings (loss) per share, Diluted	$ 0.69	$ 0.43	$ 1.71	$ 2.51

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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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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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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