Asset Quality - Schedule of Performance of Loans That Have Been Modified in the Last 12 Months (Details) $ in Millions	Mar. 31, 2023 USD ($)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	$ 93
Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	89
30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	3
90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	1
Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	88
Total commercial loans | Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	84
Total commercial loans | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	3
Total commercial loans | 90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	1
Total commercial loans | Commercial and Industrial
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	84
Total commercial loans | Commercial and Industrial | Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	80
Total commercial loans | Commercial and Industrial | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	3
Total commercial loans | Commercial and Industrial | 90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	1
Total commercial loans | Commercial mortgage
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	4
Total commercial loans | Commercial mortgage | Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	4
Total commercial loans | Commercial mortgage | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total commercial loans | Commercial mortgage | 90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total commercial loans | Construction
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total commercial loans | Construction | Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total commercial loans | Construction | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total commercial loans | Construction | 90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total commercial loans | Total commercial real estate loans
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	88
Total commercial loans | Total commercial real estate loans | Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	84
Total commercial loans | Total commercial real estate loans | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	3
Total commercial loans | Total commercial real estate loans | 90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	1
Total commercial loans | Commercial lease financing
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total commercial loans | Commercial lease financing | Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total commercial loans | Commercial lease financing | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total commercial loans | Commercial lease financing | 90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	5
Total consumer loans | Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	5
Total consumer loans | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | 90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | Real estate — residential mortgage
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	1
Total consumer loans | Real estate — residential mortgage | Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	1
Total consumer loans | Real estate — residential mortgage | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | Real estate — residential mortgage | 90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | Home equity loans
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	2
Total consumer loans | Home equity loans | Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	2
Total consumer loans | Home equity loans | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | Home equity loans | 90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | Consumer direct loans
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	1
Total consumer loans | Consumer direct loans | Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	1
Total consumer loans | Consumer direct loans | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | Consumer direct loans | 90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | Credit cards
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	1
Total consumer loans | Credit cards | Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	1
Total consumer loans | Credit cards | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | Credit cards | 90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | Consumer indirect loans
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | Consumer indirect loans | Current (b)
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | Consumer indirect loans | 30-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	0
Total consumer loans | Consumer indirect loans | 90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans modified in last 12 months	$ 0