Regulatory Matters (Narrative) (Details) $ in Millions	3 Months Ended
	Dec. 31, 2023 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount available for dividend payments to parent company without prior regulatory approval	$ 6,300
Outstanding cash reserves at the Federal Reserve Bank	43,300
FDIC-Related Assessments
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Loss contingency	515
Expense, post tax	$ 407