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Stock-Based Compensation (Weighted Average Assumptions Used to Estimate Fair Value of Stock Option Grants) (Details) - Incentive and Non-Statutory Stock Options [Member] - USD ($)
6 Months Ended
Mar. 26, 2019
Mar. 27, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (years) 7 years 6 months 7 years 6 months
Expected volatility, minimum 70.65% 75.33%
Expected volatility, maximum 70.80% 75.67%
Risk-free interest rate, minimum 3.01% 2.17%
Risk-free interest rate, maximum 3.10% 2.35%
Expected dividends