Derivative instruments - Offsetting (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Derivative Asset
Derivatives subject to netting arrangements, Gross assets recognized	$ 11,857	$ 8,302
Total derivatives subject to netting arrangements, Gross amounts offset in the balance sheet	9,379	6,973
Derivatives subject to netting arrangements, Net assets recognized in the balance sheet	2,478	1,329
Total derivatives, Gross amounts not offset in the balance sheet, Financial instruments	169	275
Total derivatives, Gross amounts not offset in the balance sheet, Cash collateral received	0	0
Derivative assets subject to netting arrangements, Net amount	2,309	1,054
Total derivatives not subject to netting arrangements	1,116	1,491
Total derivatives, Gross assets recognized	12,973	9,793
Fair value after effect of master netting agreements	3,594	2,820
Total derivatives, Net amount	3,425	2,545
Reverse repurchase agreements, Gross assets recognized	51,894	72,661
Reverse repurchase agreements, Gross amounts offset in the balance sheet	37,436	54,709
Reverse repurchase agreements, Net assets recognized on the balance sheet	14,458	17,952
Reverse repurchase agreements, Gross amounts not offset in the balance sheet, Financial instruments	14,458	17,922
Reverse repurchase agreements, Gross amounts not offset in the balance sheet, Cash collateral received	0	0
Reverse repurchase agreements, Net amount	0	30
Securities borrowing, Gross assets recognized	8,482	11,655
Securities borrowing, Net assets recognized on the balance sheet	8,482	11,655
Securities borrowing, Gross amounts not offset in the balance sheet, Financial instruments	8,082	11,036
Securities borrowing, Net amount	400	619
Total, Gross assets recognized	73,349	94,109
Total, Gross amounts offset in the balance sheet	46,815	61,682
Total, Net assets recognized on the balance sheet	26,534	32,427
Total, Gross amounts not offset in the balance sheet, Financial instruments	22,709	29,233
Total, Gross amounts not offset in the balance sheet, Cash collateral received	0	0
Total, Net amount	3,825	3,194
Derivative Liability
Derivatives subject to netting arrangements, Gross liabilities recognized	11,414	9,093
Derivatives subject to netting arrangements, Gross amounts offset in the balance sheet	9,854	6,335
Derivatives subject to netting arrangements, Net liabilities recognized in the balance sheet	1,560	2,758
Total derivatives, Gross amounts not offset in the balance sheet, Financial instruments	246	1,226
Total derivatives, Gross amounts not offset in the balance sheet, Cash collateral pledged	0	0
Derivative liabilities subject to netting arrangements, Net amount	1,314	1,532
Total derivatives not subject to netting arrangements	870	666
Total derivatives, Gross liabilities recognized	12,284	9,759
Fair value after effect of master netting agreements	2,430	3,424
Total derivatives, Net amount	2,184	2,198
Repurchase agreements, Gross liabilities recognized	47,048	64,734
Repurchase agreements, Gross amounts offset in the balance sheet	37,436	54,709
Repurchase agreements, Net liabilities recognized on the balance sheet	9,612	10,025
Repurchase agreements, Gross amounts not offset in the balance sheet, Financial instruments	9,597	10,025
Repurchase agreements, Gross amounts not offset in the balance sheet, Cash collateral pledged	9	0
Repurchase agreements, Net amount	6	0
Securities lending, Gross liabilities recognized	1,822	1,541
Securities lending, Net liabilities recognized on the balance sheet	1,822	1,541
Securities lending, Gross amounts not offset in the balance sheet, Financial instruments	1,723	1,478
Securities lending, Net amount	99	63
Total, Gross liabilities recognized	61,154	76,034
Total, Gross amounts offset in the balance sheet	47,290	61,044
Total, Net liabilities recognized on the balance sheet	13,864	14,990
Total, Gross amounts not offset in the balance sheet, Financial instruments	11,566	12,729
Total, Gross amounts not offset in the balance sheet, Cash collateral pledged	9	0
Total, Net amount	2,289	2,261
Interest rate contracts
Derivative Asset
Derivatives subject to netting arrangements, Gross assets recognized	1,227	2,132
Total derivatives subject to netting arrangements, Gross amounts offset in the balance sheet	920	1,424
Derivatives subject to netting arrangements, Net assets recognized in the balance sheet	307	708
Total derivatives, Gross amounts not offset in the balance sheet, Financial instruments	69	206
Total derivatives, Gross amounts not offset in the balance sheet, Cash collateral received	0	0
Derivative assets subject to netting arrangements, Net amount	238	502
Derivative Liability
Derivatives subject to netting arrangements, Gross liabilities recognized	1,639	3,263
Derivatives subject to netting arrangements, Gross amounts offset in the balance sheet	1,255	2,028
Derivatives subject to netting arrangements, Net liabilities recognized in the balance sheet	384	1,235
Total derivatives, Gross amounts not offset in the balance sheet, Financial instruments	103	1,197
Total derivatives, Gross amounts not offset in the balance sheet, Cash collateral pledged	0	0
Derivative liabilities subject to netting arrangements, Net amount	281	38
Foreign exchange contracts
Derivative Asset
Derivatives subject to netting arrangements, Gross assets recognized	10,402	6,122
Total derivatives subject to netting arrangements, Gross amounts offset in the balance sheet	8,387	5,501
Derivatives subject to netting arrangements, Net assets recognized in the balance sheet	2,015	621
Total derivatives, Gross amounts not offset in the balance sheet, Financial instruments	59	69
Total derivatives, Gross amounts not offset in the balance sheet, Cash collateral received	0	0
Derivative assets subject to netting arrangements, Net amount	1,956	552
Derivative Liability
Derivatives subject to netting arrangements, Gross liabilities recognized	9,723	5,619
Derivatives subject to netting arrangements, Gross amounts offset in the balance sheet	8,563	4,111
Derivatives subject to netting arrangements, Net liabilities recognized in the balance sheet	1,160	1,508
Total derivatives, Gross amounts not offset in the balance sheet, Financial instruments	143	29
Total derivatives, Gross amounts not offset in the balance sheet, Cash collateral pledged	0	0
Derivative liabilities subject to netting arrangements, Net amount	1,017	1,479
Equity and other contracts
Derivative Asset
Derivatives subject to netting arrangements, Gross assets recognized	228	48
Total derivatives subject to netting arrangements, Gross amounts offset in the balance sheet	72	48
Derivatives subject to netting arrangements, Net assets recognized in the balance sheet	156	0
Total derivatives, Gross amounts not offset in the balance sheet, Financial instruments	41	0
Total derivatives, Gross amounts not offset in the balance sheet, Cash collateral received	0	0
Derivative assets subject to netting arrangements, Net amount	115	0
Derivative Liability
Derivatives subject to netting arrangements, Gross liabilities recognized	52	211
Derivatives subject to netting arrangements, Gross amounts offset in the balance sheet	36	196
Derivatives subject to netting arrangements, Net liabilities recognized in the balance sheet	16	15
Total derivatives, Gross amounts not offset in the balance sheet, Financial instruments	0	0
Total derivatives, Gross amounts not offset in the balance sheet, Cash collateral pledged	0	0
Derivative liabilities subject to netting arrangements, Net amount	$ 16	$ 15