v3.26.1
AVAILABLE-FOR-SALE SECURITIES, Narrative (Details)
$ in Millions
3 Months Ended 6 Months Ended
Mar. 31, 2026
USD ($)
security
Mar. 31, 2025
USD ($)
Mar. 31, 2026
USD ($)
security
Mar. 31, 2025
USD ($)
Sep. 30, 2025
USD ($)
Debt Securities, Available-for-sale [Line Items]          
Accrued interest excluded | $ $ 17   $ 17   $ 18
Accrued interest on available-for-sale securities, location Other receivables, net   Other receivables, net   Other receivables, net
Average expected duration, available for sale securities     3 years 10 months 24 days    
Proceeds from sales of available-for-sale securities | $ $ 0 $ 0 $ 0 $ 78  
Losses reclassified from AOCI | $       $ 2  
Agency MBS and agency CMOs          
Debt Securities, Available-for-sale [Line Items]          
Number of available-for-sale securities determined to be in an unrealized loss position | security 789   789    
Number of available-for-sale securities determined to be in an unrealized loss position continuously for less than 12 months | security 47   47    
Number of available-for-sale securities determined to be in an unrealized loss position continuously for 12 months or more | security 742   742