Credit Quality and the Allowance for Loan and Lease Losses - Summary of Amortized Cost Basis of Consumer Loans That Were Modified for Borrowers Experiencing Financial Difficulty (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 362	$ 254
Loan modification program, percentage of modifications to total portfolio	0.21%	0.21%
Consumer
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 12	$ 12
Loan modification program, percentage of modifications to total portfolio	0.04%	0.04%
Consumer \| Contractual Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 6	$ 7
Consumer \| Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1	2
Consumer \| Other
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	5	3
Consumer \| Home equity
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 5	$ 4
Loan modification program, percentage of modifications to total portfolio	0.07%	0.09%
Consumer \| Home equity \| Contractual Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 1
Consumer \| Home equity \| Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer \| Home equity \| Other
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	5	3
Consumer \| Credit card
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 6	$ 6
Loan modification program, percentage of modifications to total portfolio	0.36%	0.36%
Consumer \| Credit card \| Contractual Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 6	$ 6
Consumer \| Credit card \| Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer \| Credit card \| Other
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer \| Solar energy installation loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 1
Loan modification program, percentage of modifications to total portfolio	0.00%	0.02%
Consumer \| Solar energy installation loans \| Contractual Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 0
Consumer \| Solar energy installation loans \| Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	1
Consumer \| Solar energy installation loans \| Other
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer \| Other consumer loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 1	$ 1
Loan modification program, percentage of modifications to total portfolio	0.04%	0.04%
Consumer \| Other consumer loans \| Contractual Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 0
Consumer \| Other consumer loans \| Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1	1
Consumer \| Other consumer loans \| Other
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 0

Credit Quality and the Allowance for Loan and Lease Losses - Summary of Amortized Cost Basis of Consumer Loans That Were Modified for Borrowers Experiencing Financial Difficulty (Details) - USD ($)
$ in Millions