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Stockholders' Equity - Fair Value Calculations Stock-based Compensation Awards (Details)
12 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2017
Equity [Abstract]      
Risk-free interest rate, minimum 1.85% 2.04% 1.68%
Risk-free interest rate, maximum 3.08%   1.92%
Expected life (years) 5 years 5 months 4 days 5 years 1 month 24 days 5 years 3 months
Expected volatility rate 57.00% 60.00% 74.00%
Expected dividend rate 0.00% 0.00% 0.00%