Loans and asset quality - Credit Risk Profile by Grade (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	$ 8,813	$ 13,289
Originated, at amortized cost, fiscal year before current fiscal year	4,237	1,738
Originated, at amortized cost, two years before current fiscal year	1,627	2,194
Originated, at amortized cost, three years before current fiscal year	1,986	1,090
Originated, at amortized cost, four years before current fiscal year	835	1,484
Originated, at amortized cost, more than five years before current fiscal year	5,327	4,627
Amortized cost	41,881	40,279
Converted to term loans – Amortized cost	23	26
Total	64,729	64,727
Accrued interest receivable	183	61
Loans	69,829	67,787
Total wealth management loans
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	28	118
Originated, at amortized cost, fiscal year before current fiscal year	58	18
Originated, at amortized cost, two years before current fiscal year	18	73
Originated, at amortized cost, three years before current fiscal year	47	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	228	122
Amortized cost	10,297	9,351
Converted to term loans – Amortized cost	0	0
Total	10,676	9,792
Accrued interest receivable	38	12
Total wealth management loans | Wealth management mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	1,523	2,058
Originated, at amortized cost, fiscal year before current fiscal year	1,997	1,008
Originated, at amortized cost, two years before current fiscal year	934	855
Originated, at amortized cost, three years before current fiscal year	788	542
Originated, at amortized cost, four years before current fiscal year	494	885
Originated, at amortized cost, more than five years before current fiscal year	3,120	2,838
Amortized cost	22	14
Converted to term loans – Amortized cost	0	0
Total	8,878	8,200
Accrued interest receivable	18	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	356	299
Amortized cost	0	0
Converted to term loans – Amortized cost	0	0
Total	356	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	3,985	2,284
Converted to term loans – Amortized cost	0	0
Total	3,985	2,284
Accrued interest receivable	18	3
Loans	3,985	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	2,884	2,541
Converted to term loans – Amortized cost	0	0
Total	2,884	2,541
Accrued interest receivable	4	2
Loans	2,884	2,541
Margin loans
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	5,259	7,697
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	12,450	14,790
Converted to term loans – Amortized cost	0	0
Total	17,709	22,487
Accrued interest receivable	24	10
Loans	17,709	22,487
Overdrafts
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	$ 5,100	$ 3,060
Overdraft repayment period	2 days	2 days
Overdrafts | Overdrafts
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	$ 5,100	$ 3,060
Investment grade | Total wealth management loans | Loans receivable
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	28	117
Originated, at amortized cost, fiscal year before current fiscal year	58	18
Originated, at amortized cost, two years before current fiscal year	18	73
Originated, at amortized cost, three years before current fiscal year	47	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	228	122
Amortized cost	10,264	9,320
Converted to term loans – Amortized cost	0	0
Total	10,643	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	33	31
Converted to term loans – Amortized cost	0	0
Total	33	32
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	404	429
Originated, at amortized cost, fiscal year before current fiscal year	174	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	13	145
Originated, at amortized cost, more than five years before current fiscal year	45	0
Amortized cost	1,479	1,526
Converted to term loans – Amortized cost	0	0
Total	2,135	2,128
Accrued interest receivable	3	1
Commercial | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	322	348
Originated, at amortized cost, fiscal year before current fiscal year	168	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	13	145
Originated, at amortized cost, more than five years before current fiscal year	45	0
Amortized cost	1,402	1,450
Converted to term loans – Amortized cost	0	0
Total	1,970	1,971
Commercial | Non-investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	82	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	77	76
Converted to term loans – Amortized cost	0	0
Total	165	157
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	1,335	2,237
Originated, at amortized cost, fiscal year before current fiscal year	1,617	625
Originated, at amortized cost, two years before current fiscal year	603	1,251
Originated, at amortized cost, three years before current fiscal year	1,140	524
Originated, at amortized cost, four years before current fiscal year	321	348
Originated, at amortized cost, more than five years before current fiscal year	931	696
Amortized cost	329	326
Converted to term loans – Amortized cost	23	26
Total	6,299	6,033
Accrued interest receivable	20	7
Commercial real estate | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	919	1,577
Originated, at amortized cost, fiscal year before current fiscal year	1,172	528
Originated, at amortized cost, two years before current fiscal year	458	683
Originated, at amortized cost, three years before current fiscal year	904	173
Originated, at amortized cost, four years before current fiscal year	212	298
Originated, at amortized cost, more than five years before current fiscal year	912	601
Amortized cost	296	205
Converted to term loans – Amortized cost	0	0
Total	4,873	4,065
Commercial real estate | Non-investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	416	660
Originated, at amortized cost, fiscal year before current fiscal year	445	97
Originated, at amortized cost, two years before current fiscal year	145	568
Originated, at amortized cost, three years before current fiscal year	236	351
Originated, at amortized cost, four years before current fiscal year	109	50
Originated, at amortized cost, more than five years before current fiscal year	19	95
Amortized cost	33	121
Converted to term loans – Amortized cost	23	26
Total	1,426	1,968
Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	246	725
Originated, at amortized cost, fiscal year before current fiscal year	391	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	33	60
Amortized cost	10,435	9,447
Converted to term loans – Amortized cost	0	0
Total	11,105	10,232
Accrued interest receivable	57	11
Financial institutions | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	176	705
Originated, at amortized cost, fiscal year before current fiscal year	391	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	33	60
Amortized cost	9,029	8,015
Converted to term loans – Amortized cost	0	0
Total	9,629	8,780
Financial institutions | Non-investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	70	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	1,406	1,432
Converted to term loans – Amortized cost	0	0
Total	1,476	1,452
Lease financings
Financing Receivable, Credit Quality Indicator [Line Items]
Originated, at amortized cost, current fiscal year	18	25
Originated, at amortized cost, fiscal year before current fiscal year	0	67
Originated, at amortized cost, two years before current fiscal year	52	15
Originated, at amortized cost, three years before current fiscal year	11	10
Originated, at amortized cost, four years before current fiscal year	7	2
Originated, at amortized cost, more than five years before current fiscal year	614	612
Amortized cost	0	0
Converted to term loans – Amortized cost	0	0
Total	702	731
Accrued interest receivable	$ 0	$ 0