Loans, Leases, and Allowance for Credit Losses (Summary Aging Analysis, Modified) (Details) - USD ($) $ in Millions	Jun. 30, 2024	Jun. 30, 2023
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	$ 318	$ 148
Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	283	144
30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	27	3
90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	8	1
Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	35	4
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	107	69
Commercial | Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	102	65
Commercial | 30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	1	3
Commercial | 90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	4	1
Commercial | Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	5	4
Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	88	43
Commercial | Commercial and industrial | Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	83	40
Commercial | Commercial and industrial | 30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	1	3
Commercial | Commercial and industrial | 90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	4	0
Commercial | Commercial and industrial | Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	5	3
Commercial | Owner-occupied
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	8	26
Commercial | Owner-occupied | Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	8	25
Commercial | Owner-occupied | 30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0	0
Commercial | Owner-occupied | 90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0	1
Commercial | Owner-occupied | Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0	1
Commercial | Municipal
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	11
Commercial | Municipal | Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	11
Commercial | Municipal | 30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0
Commercial | Municipal | 90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0
Commercial | Municipal | Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	205	76
Commercial real estate | Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	175	76
Commercial real estate | 30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	26	0
Commercial real estate | 90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	4	0
Commercial real estate | Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	30	0
Commercial real estate | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	21	18
Commercial real estate | Construction and land development | Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	19	18
Commercial real estate | Construction and land development | 30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0	0
Commercial real estate | Construction and land development | 90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	2	0
Commercial real estate | Construction and land development | Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	2	0
Commercial real estate | Term
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	184	58
Commercial real estate | Term | Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	156	58
Commercial real estate | Term | 30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	26	0
Commercial real estate | Term | 90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	2	0
Commercial real estate | Term | Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	28	0
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	6	3
Consumer | Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	6	3
Consumer | 30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0	0
Consumer | 90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0	0
Consumer | Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0	0
Consumer | Home equity credit line
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	1
Consumer | Home equity credit line | Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	1
Consumer | Home equity credit line | 30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0
Consumer | Home equity credit line | 90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0
Consumer | Home equity credit line | Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0
Consumer | 1-4 family residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	4	2
Consumer | 1-4 family residential | Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	4	2
Consumer | 1-4 family residential | 30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0	0
Consumer | 1-4 family residential | 90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0	0
Consumer | 1-4 family residential | Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0	0
Consumer | Bankcard and other revolving plans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		1
Consumer | Bankcard and other revolving plans | Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		1
Consumer | Bankcard and other revolving plans | 30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		0
Consumer | Bankcard and other revolving plans | 90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		0
Consumer | Bankcard and other revolving plans | Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		$ 0
Consumer | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	1
Consumer | Other | Current
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	1
Consumer | Other | 30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0
Consumer | Other | 90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	0
Consumer | Other | Total past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	$ 0