Loans and asset quality - Credit Risk Profile by Grade (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	$ 7,967	$ 13,289
Originated, at amortized cost, fiscal year before current fiscal year	5,289	1,738
Originated, at amortized cost, two years before current fiscal year	1,659	2,194
Originated, at amortized cost, three years before current fiscal year	2,081	1,090
Originated, at amortized cost, four years before current fiscal year	895	1,484
Originated, at amortized cost, more than five years before current fiscal year	5,615	4,627
Amortized cost	42,023	40,279
Converted to term loans – Amortized cost	25	26
Total	65,554	64,727
Accrued interest receivable	110	61
Loans	69,347	67,787
Total wealth management loans
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	22	118
Originated, at amortized cost, fiscal year before current fiscal year	105	18
Originated, at amortized cost, two years before current fiscal year	18	73
Originated, at amortized cost, three years before current fiscal year	71	6
Originated, at amortized cost, four years before current fiscal year	0	104
Originated, at amortized cost, more than five years before current fiscal year	226	122
Amortized cost	10,411	9,351
Converted to term loans – Amortized cost	0	0
Total	10,853	9,792
Accrued interest receivable	22	12
Total wealth management loans | Wealth management mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	1,169	2,058
Originated, at amortized cost, fiscal year before current fiscal year	2,031	1,008
Originated, at amortized cost, two years before current fiscal year	959	855
Originated, at amortized cost, three years before current fiscal year	805	542
Originated, at amortized cost, four years before current fiscal year	508	885
Originated, at amortized cost, more than five years before current fiscal year	3,289	2,838
Amortized cost	16	14
Converted to term loans – Amortized cost	0	0
Total	8,777	8,200
Accrued interest receivable	17	14
Other residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	0	0
Originated, at amortized cost, fiscal year before current fiscal year	0	0
Originated, at amortized cost, two years before current fiscal year	0	0
Originated, at amortized cost, three years before current fiscal year	0	0
Originated, at amortized cost, four years before current fiscal year	0	0
Originated, at amortized cost, more than five years before current fiscal year	369	299
Amortized cost	0	0
Converted to term loans – Amortized cost	0	0
Total	369	299
Accrued interest receivable	1	1
Capital call financing
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	0	0
Originated, at amortized cost, fiscal year before current fiscal year	0	0
Originated, at amortized cost, two years before current fiscal year	0	0
Originated, at amortized cost, three years before current fiscal year	0	0
Originated, at amortized cost, four years before current fiscal year	0	0
Originated, at amortized cost, more than five years before current fiscal year	0	0
Amortized cost	3,602	2,284
Converted to term loans – Amortized cost	0	0
Total	3,602	2,284
Accrued interest receivable	10	3
Loans	3,602	2,284
Other
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	0	0
Originated, at amortized cost, fiscal year before current fiscal year	0	0
Originated, at amortized cost, two years before current fiscal year	0	0
Originated, at amortized cost, three years before current fiscal year	0	0
Originated, at amortized cost, four years before current fiscal year	0	0
Originated, at amortized cost, more than five years before current fiscal year	0	0
Amortized cost	2,790	2,541
Converted to term loans – Amortized cost	0	0
Total	2,790	2,541
Accrued interest receivable	3	2
Loans	2,790	2,541
Margin loans
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	5,119	7,697
Originated, at amortized cost, fiscal year before current fiscal year	500	0
Originated, at amortized cost, two years before current fiscal year	0	0
Originated, at amortized cost, three years before current fiscal year	0	0
Originated, at amortized cost, four years before current fiscal year	0	0
Originated, at amortized cost, more than five years before current fiscal year	0	0
Amortized cost	13,697	14,790
Converted to term loans – Amortized cost	0	0
Total	19,316	22,487
Accrued interest receivable	17	10
Loans	19,316	22,487
Overdrafts
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	$ 3,793	$ 3,060
Overdraft repayment period	2 days	2 days
Overdrafts | Overdrafts
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	$ 3,793	$ 3,060
Investment grade | Total wealth management loans | Loans receivable
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	22	117
Originated, at amortized cost, fiscal year before current fiscal year	105	18
Originated, at amortized cost, two years before current fiscal year	18	73
Originated, at amortized cost, three years before current fiscal year	71	6
Originated, at amortized cost, four years before current fiscal year	0	104
Originated, at amortized cost, more than five years before current fiscal year	226	122
Amortized cost	10,353	9,320
Converted to term loans – Amortized cost	0	0
Total	10,795	9,760
Non-investment grade | Total wealth management loans | Loans receivable
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	0	1
Originated, at amortized cost, fiscal year before current fiscal year	0	0
Originated, at amortized cost, two years before current fiscal year	0	0
Originated, at amortized cost, three years before current fiscal year	0	0
Originated, at amortized cost, four years before current fiscal year	0	0
Originated, at amortized cost, more than five years before current fiscal year	0	0
Amortized cost	58	31
Converted to term loans – Amortized cost	0	0
Total	58	32
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	461	429
Originated, at amortized cost, fiscal year before current fiscal year	330	20
Originated, at amortized cost, two years before current fiscal year	20	0
Originated, at amortized cost, three years before current fiscal year	0	8
Originated, at amortized cost, four years before current fiscal year	17	145
Originated, at amortized cost, more than five years before current fiscal year	145	0
Amortized cost	1,450	1,526
Converted to term loans – Amortized cost	0	0
Total	2,423	2,128
Accrued interest receivable	2	1
Commercial | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	375	348
Originated, at amortized cost, fiscal year before current fiscal year	324	20
Originated, at amortized cost, two years before current fiscal year	20	0
Originated, at amortized cost, three years before current fiscal year	0	8
Originated, at amortized cost, four years before current fiscal year	17	145
Originated, at amortized cost, more than five years before current fiscal year	145	0
Amortized cost	1,409	1,450
Converted to term loans – Amortized cost	0	0
Total	2,290	1,971
Commercial | Non-investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	86	81
Originated, at amortized cost, fiscal year before current fiscal year	6	0
Originated, at amortized cost, two years before current fiscal year	0	0
Originated, at amortized cost, three years before current fiscal year	0	0
Originated, at amortized cost, four years before current fiscal year	0	0
Originated, at amortized cost, more than five years before current fiscal year	0	0
Amortized cost	41	76
Converted to term loans – Amortized cost	0	0
Total	133	157
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	955	2,237
Originated, at amortized cost, fiscal year before current fiscal year	1,757	625
Originated, at amortized cost, two years before current fiscal year	608	1,251
Originated, at amortized cost, three years before current fiscal year	1,192	524
Originated, at amortized cost, four years before current fiscal year	362	348
Originated, at amortized cost, more than five years before current fiscal year	940	696
Amortized cost	256	326
Converted to term loans – Amortized cost	25	26
Total	6,095	6,033
Accrued interest receivable	12	7
Commercial real estate | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	568	1,577
Originated, at amortized cost, fiscal year before current fiscal year	1,288	528
Originated, at amortized cost, two years before current fiscal year	452	683
Originated, at amortized cost, three years before current fiscal year	814	173
Originated, at amortized cost, four years before current fiscal year	173	298
Originated, at amortized cost, more than five years before current fiscal year	890	601
Amortized cost	233	205
Converted to term loans – Amortized cost	0	0
Total	4,418	4,065
Commercial real estate | Non-investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	387	660
Originated, at amortized cost, fiscal year before current fiscal year	469	97
Originated, at amortized cost, two years before current fiscal year	156	568
Originated, at amortized cost, three years before current fiscal year	378	351
Originated, at amortized cost, four years before current fiscal year	189	50
Originated, at amortized cost, more than five years before current fiscal year	50	95
Amortized cost	23	121
Converted to term loans – Amortized cost	25	26
Total	1,677	1,968
Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	222	725
Originated, at amortized cost, fiscal year before current fiscal year	566	0
Originated, at amortized cost, two years before current fiscal year	0	0
Originated, at amortized cost, three years before current fiscal year	0	0
Originated, at amortized cost, four years before current fiscal year	0	0
Originated, at amortized cost, more than five years before current fiscal year	38	60
Amortized cost	9,801	9,447
Converted to term loans – Amortized cost	0	0
Total	10,627	10,232
Accrued interest receivable	26	11
Financial institutions | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	162	705
Originated, at amortized cost, fiscal year before current fiscal year	566	0
Originated, at amortized cost, two years before current fiscal year	0	0
Originated, at amortized cost, three years before current fiscal year	0	0
Originated, at amortized cost, four years before current fiscal year	0	0
Originated, at amortized cost, more than five years before current fiscal year	38	60
Amortized cost	8,240	8,015
Converted to term loans – Amortized cost	0	0
Total	9,006	8,780
Financial institutions | Non-investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	60	20
Originated, at amortized cost, fiscal year before current fiscal year	0	0
Originated, at amortized cost, two years before current fiscal year	0	0
Originated, at amortized cost, three years before current fiscal year	0	0
Originated, at amortized cost, four years before current fiscal year	0	0
Originated, at amortized cost, more than five years before current fiscal year	0	0
Amortized cost	1,561	1,432
Converted to term loans – Amortized cost	0	0
Total	1,621	1,452
Lease financings
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	19	25
Originated, at amortized cost, fiscal year before current fiscal year	0	67
Originated, at amortized cost, two years before current fiscal year	54	15
Originated, at amortized cost, three years before current fiscal year	13	10
Originated, at amortized cost, four years before current fiscal year	8	2
Originated, at amortized cost, more than five years before current fiscal year	608	612
Amortized cost	0	0
Converted to term loans – Amortized cost	0	0
Total	702	731
Accrued interest receivable	$ 0	$ 0