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Stockholders' Equity (Schedule of Assumptions Used in Estimate of Fair Value of Stock Option Awards) (Details) - Stock Options [Member] - $ / shares
12 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Weighted-average exercise price per share $ 82.46 $ 90.52 $ 79.84
Minimum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Expected term (years) 6 years 6 months 6 years 4 months 24 days 6 years 6 months
Estimated volatility 33.30% 25.70% 25.70%
Estimated dividend yield 0.30% 0.40% 0.60%
Risk-free interest rate 0.40% 0.40% 1.50%
Maximum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Expected term (years) 8 years 8 months 12 days 8 years 8 months 12 days 8 years 8 months 12 days
Estimated volatility 36.20% 35.10% 31.00%
Estimated dividend yield 0.60% 0.90% 0.80%
Risk-free interest rate 1.00% 1.70% 3.10%