v3.26.1
Fair Value Measurements - Narrative (Details)
$ in Millions, € in Billions, ¥ in Billions
3 Months Ended 6 Months Ended
Mar. 31, 2026
USD ($)
Mar. 31, 2025
USD ($)
Mar. 31, 2026
USD ($)
Mar. 31, 2025
USD ($)
Mar. 31, 2026
EUR (€)
Mar. 31, 2026
JPY (¥)
Sep. 30, 2025
USD ($)
Sep. 30, 2025
EUR (€)
Sep. 30, 2025
JPY (¥)
Fair Value [Line Items]                  
Equity securities, unrealized losses $ 11 $ 8 $ 7 $ 10          
Net Investment Hedging                  
Fair Value [Line Items]                  
Pre-tax gains (losses) related to net investment hedges recorded in other comprehensive income (loss) 77 $ (131) 93 $ 107          
Foreign currency denominated debt                  
Fair Value [Line Items]                  
Derivative, notional amount         € 2.9 ¥ 30   € 2.9 ¥ 30
Foreign currency denominated debt | Derivatives and Hedging Activities  Designated as Hedging Instruments                  
Fair Value [Line Items]                  
Derivative liabilities $ 3,400   $ 3,400       $ 3,600