Loans - Gross Charge-Offs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 177	$ 87	$ 62
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	3	4	0
One year prior to current year	23	0	0
Two years prior to current year	30	0	17
Three years prior to current year	0	32	0
Four years prior to current year	23	0	0
Prior	77	41	11
Revolving loans	12	1	20
Revolving Loans Converted to Term Loans	0	0	0
Total	168	78	48
Commercial loans | Real estate, including construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	0
One year prior to current year	0	0
Two years prior to current year	0	0
Three years prior to current year	0	0
Four years prior to current year	4	0
Prior	60	17
Revolving loans	0	0
Revolving Loans Converted to Term Loans	0	0
Total	64	17	0
Commercial loans | Business and corporate banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	3	4	0
One year prior to current year	23	0	0
Two years prior to current year	30	0	17
Three years prior to current year	0	32	0
Four years prior to current year	19	0	0
Prior	17	24	11
Revolving loans	12	1	20
Revolving Loans Converted to Term Loans	0	0	0
Total	104	61	48
Commercial loans | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 0	$ 0	$ 0