XML 122 R109.htm IDEA: XBRL DOCUMENT v3.20.2
Stock Compensation Plans: Fair Value Assumptions (Details) - Stock Options - $ / shares
12 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected volatility (as a percent) 33.00% 29.00% 17.00%
Expected life (in years) 5 years 5 years 5 years
Expected dividend yield (as a percent) 5.36% 3.28% 2.61%
Risk free interest rate (as a percent) 0.28% 1.53% 2.97%
Grant date fair value per share (in dollars per share) $ 2.70 $ 5.12 $ 4.48