v3.26.3
Share-Based Compensation - Narrative (Details) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2024
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Pre-tax share-based compensation expense $ 92 $ 85 $ 100
Income tax benefit related to share-based compensation expense 14 $ 13 $ 16
Unrecognized compensation cost related to share-based compensation awards, net of estimated forfeitures $ 91    
Weighted average period for recognition of total unrecognized compensation cost 1 year 8 months 12 days    
Shares authorized (up to) (in shares) 10,600,000    
Shares available for grant (in shares) 10,600,000    
Stock options      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Expiration period 10 years    
Vesting period 3 years    
Per share weighted average fair value of stock options granted (in dollars per share) $ 117.15 $ 93.48 $ 85.63
Total intrinsic value of stock options exercised $ 90 $ 75 $ 27
Performance shares      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Vesting period 3 years 3 years  
Percent payout 70.00% 0.00% 92.00%
Payout percentage in December 2020 for performance period ending September 30, 2020 116.00%    
Maximum potential shares to be delivered in payment under performance share awards (in shares) 70,000    
Weighted average grant date fair value of awards granted (in dollars per share) $ 591.67 $ 387.72 $ 295.06
Total fair value of shares vested $ 14 $ 0 $ 9
Shares granted in the period (in shares) 51,000    
Performance shares | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Percent payout 0.00%    
Performance shares | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Percent payout 200.00%    
Restricted stock and restricted stock units      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Weighted average grant date fair value of awards granted (in dollars per share) $ 402.40 $ 299.05 $ 276.34
Total fair value of shares vested $ 70 $ 64 $ 60
Shares granted in the period (in shares) 172,000    
Restricted stock and restricted stock units | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Vesting period 1 year    
Restricted stock and restricted stock units | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Vesting period 3 years    
Unrestricted stock      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Weighted average grant date fair value of awards granted (in dollars per share) $ 405.81 $ 297.10 $ 278.35
Shares granted in the period (in shares) 3,700