Loans - Summary of Past Due Status of Loans With Payment Modifications (Details) - Commercial loans - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Financing Receivable, Past Due [Line Items]
Modified loans, past due	$ 353	$ 438
Real estate, including construction
Financing Receivable, Past Due [Line Items]
Modified loans, past due	95	232
Business and corporate banking
Financing Receivable, Past Due [Line Items]
Modified loans, past due	258	206
30 - 89 Days
Financing Receivable, Past Due [Line Items]
Modified loans, past due	0	0
30 - 89 Days | Real estate, including construction
Financing Receivable, Past Due [Line Items]
Modified loans, past due	0	0
30 - 89 Days | Business and corporate banking
Financing Receivable, Past Due [Line Items]
Modified loans, past due	0	0
90+ Days
Financing Receivable, Past Due [Line Items]
Modified loans, past due	27	29
90+ Days | Real estate, including construction
Financing Receivable, Past Due [Line Items]
Modified loans, past due	18	0
90+ Days | Business and corporate banking
Financing Receivable, Past Due [Line Items]
Modified loans, past due	9	29
Current
Financing Receivable, Past Due [Line Items]
Modified loans, past due	326	409
Current | Real estate, including construction
Financing Receivable, Past Due [Line Items]
Modified loans, past due	77	232
Current | Business and corporate banking
Financing Receivable, Past Due [Line Items]
Modified loans, past due	$ 249	$ 177