Derivative Instruments and Hedging Activities - Fair Values of Derivative Contracts (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Derivative Assets
Total gross derivatives	$ 335,939	$ 326,450
Counterparty netting	(260,202)	(246,914)
Cash collateral netting	(38,510)	(42,223)
Total in Trading assets	37,227	37,313
Financial instruments collateral	(15,407)	(15,690)
Net amounts	21,820	21,623
Net amounts for which master netting or collateral agreements are not in place or may not be legally enforceable	2,592	2,641
Derivative Liabilities
Total gross derivatives	334,342	324,254
Counterparty netting	(260,202)	(246,914)
Cash collateral netting	(41,521)	(42,065)
Total in Trading liabilities	32,619	35,275
Cash collateral netting	(5,788)	(6,909)
Net amounts	26,831	28,366
Net amounts for which master netting or collateral agreements are not in place or may not be legally enforceable	4,660	5,911
Designated as accounting hedges
Derivative Assets
Total gross derivatives	50	35
Derivative Liabilities
Total gross derivatives	526	924
Designated as accounting hedges | Interest rate
Derivative Assets
Total gross derivatives	3	25
Derivative Liabilities
Total gross derivatives	420	467
Designated as accounting hedges | Foreign exchange
Derivative Assets
Total gross derivatives	47	10
Derivative Liabilities
Total gross derivatives	106	457
Not designated as accounting hedges
Derivative Assets
Total gross derivatives	335,889	326,415
Derivative Liabilities
Total gross derivatives	333,816	323,330
Economic hedges of loans | Credit
Derivative Assets
Total gross derivatives	33	29
Derivative Liabilities
Total gross derivatives	839	745
Other derivatives | Interest rate
Derivative Assets
Total gross derivatives	133,509	148,182
Derivative Liabilities
Total gross derivatives	119,844	138,373
Other derivatives | Credit
Derivative Assets
Total gross derivatives	10,471	10,608
Derivative Liabilities
Total gross derivatives	10,119	10,347
Other derivatives | Foreign exchange
Derivative Assets
Total gross derivatives	81,585	93,240
Derivative Liabilities
Total gross derivatives	79,802	89,904
Other derivatives | Equity
Derivative Assets
Total gross derivatives	93,110	58,075
Derivative Liabilities
Total gross derivatives	108,195	68,894
Other derivatives | Commodity and other
Derivative Assets
Total gross derivatives	17,181	16,281
Derivative Liabilities
Total gross derivatives	15,017	15,067
Bilateral OTC
Derivative Assets
Total gross derivatives	246,944	258,078
Counterparty netting	(177,423)	(184,553)
Cash collateral netting	(36,738)	(39,493)
Total in Trading assets	32,783	34,032
Financial instruments collateral	(15,407)	(15,690)
Net amounts	17,376	18,342
Derivative Liabilities
Total gross derivatives	248,365	258,334
Counterparty netting	(177,423)	(184,553)
Cash collateral netting	(40,917)	(41,082)
Total in Trading liabilities	30,025	32,699
Cash collateral netting	(5,588)	(6,864)
Net amounts	24,437	25,835
Bilateral OTC | Designated as accounting hedges
Derivative Assets
Total gross derivatives	47	30
Derivative Liabilities
Total gross derivatives	491	881
Bilateral OTC | Designated as accounting hedges | Interest rate
Derivative Assets
Total gross derivatives	3	25
Derivative Liabilities
Total gross derivatives	420	467
Bilateral OTC | Designated as accounting hedges | Foreign exchange
Derivative Assets
Total gross derivatives	44	5
Derivative Liabilities
Total gross derivatives	71	414
Bilateral OTC | Not designated as accounting hedges
Derivative Assets
Total gross derivatives	246,897	258,048
Derivative Liabilities
Total gross derivatives	247,874	257,453
Bilateral OTC | Economic hedges of loans | Credit
Derivative Assets
Total gross derivatives	0	2
Derivative Liabilities
Total gross derivatives	53	43
Bilateral OTC | Other derivatives | Interest rate
Derivative Assets
Total gross derivatives	115,855	127,414
Derivative Liabilities
Total gross derivatives	104,680	120,604
Bilateral OTC | Other derivatives | Credit
Derivative Assets
Total gross derivatives	5,026	5,712
Derivative Liabilities
Total gross derivatives	5,071	5,920
Bilateral OTC | Other derivatives | Foreign exchange
Derivative Assets
Total gross derivatives	78,738	90,654
Derivative Liabilities
Total gross derivatives	76,813	87,104
Bilateral OTC | Other derivatives | Equity
Derivative Assets
Total gross derivatives	32,410	20,338
Derivative Liabilities
Total gross derivatives	48,782	31,545
Bilateral OTC | Other derivatives | Commodity and other
Derivative Assets
Total gross derivatives	14,868	13,928
Derivative Liabilities
Total gross derivatives	12,475	12,237
Cleared OTC
Derivative Assets
Total gross derivatives	25,576	27,412
Counterparty netting	(22,675)	(23,851)
Cash collateral netting	(1,772)	(2,730)
Total in Trading assets	1,129	831
Financial instruments collateral	0	0
Net amounts	1,129	831
Derivative Liabilities
Total gross derivatives	23,504	25,045
Counterparty netting	(22,675)	(23,851)
Cash collateral netting	(604)	(983)
Total in Trading liabilities	225	211
Cash collateral netting	0	(8)
Net amounts	225	203
Cleared OTC | Designated as accounting hedges
Derivative Assets
Total gross derivatives	3	5
Derivative Liabilities
Total gross derivatives	35	43
Cleared OTC | Designated as accounting hedges | Interest rate
Derivative Assets
Total gross derivatives	0	0
Derivative Liabilities
Total gross derivatives	0	0
Cleared OTC | Designated as accounting hedges | Foreign exchange
Derivative Assets
Total gross derivatives	3	5
Derivative Liabilities
Total gross derivatives	35	43
Cleared OTC | Not designated as accounting hedges
Derivative Assets
Total gross derivatives	25,573	27,407
Derivative Liabilities
Total gross derivatives	23,469	25,002
Cleared OTC | Economic hedges of loans | Credit
Derivative Assets
Total gross derivatives	33	27
Derivative Liabilities
Total gross derivatives	786	702
Cleared OTC | Other derivatives | Interest rate
Derivative Assets
Total gross derivatives	17,372	19,914
Derivative Liabilities
Total gross derivatives	14,939	17,179
Cleared OTC | Other derivatives | Credit
Derivative Assets
Total gross derivatives	5,445	4,896
Derivative Liabilities
Total gross derivatives	5,048	4,427
Cleared OTC | Other derivatives | Foreign exchange
Derivative Assets
Total gross derivatives	2,721	2,570
Derivative Liabilities
Total gross derivatives	2,696	2,694
Cleared OTC | Other derivatives | Equity
Derivative Assets
Total gross derivatives	0	0
Derivative Liabilities
Total gross derivatives	0	0
Cleared OTC | Other derivatives | Commodity and other
Derivative Assets
Total gross derivatives	2	0
Derivative Liabilities
Total gross derivatives	0	0
Exchange- Traded
Derivative Assets
Total gross derivatives	63,419	40,960
Counterparty netting	(60,104)	(38,510)
Cash collateral netting	0	0
Total in Trading assets	3,315	2,450
Financial instruments collateral	0	0
Net amounts	3,315	2,450
Derivative Liabilities
Total gross derivatives	62,473	40,875
Counterparty netting	(60,104)	(38,510)
Cash collateral netting	0	0
Total in Trading liabilities	2,369	2,365
Cash collateral netting	(200)	(37)
Net amounts	2,169	2,328
Exchange- Traded | Designated as accounting hedges
Derivative Assets
Total gross derivatives	0	0
Derivative Liabilities
Total gross derivatives	0	0
Exchange- Traded | Designated as accounting hedges | Interest rate
Derivative Assets
Total gross derivatives	0	0
Derivative Liabilities
Total gross derivatives	0	0
Exchange- Traded | Designated as accounting hedges | Foreign exchange
Derivative Assets
Total gross derivatives	0	0
Derivative Liabilities
Total gross derivatives	0	0
Exchange- Traded | Not designated as accounting hedges
Derivative Assets
Total gross derivatives	63,419	40,960
Derivative Liabilities
Total gross derivatives	62,473	40,875
Exchange- Traded | Economic hedges of loans | Credit
Derivative Assets
Total gross derivatives	0	0
Derivative Liabilities
Total gross derivatives	0	0
Exchange- Traded | Other derivatives | Interest rate
Derivative Assets
Total gross derivatives	282	854
Derivative Liabilities
Total gross derivatives	225	590
Exchange- Traded | Other derivatives | Credit
Derivative Assets
Total gross derivatives	0	0
Derivative Liabilities
Total gross derivatives	0	0
Exchange- Traded | Other derivatives | Foreign exchange
Derivative Assets
Total gross derivatives	126	16
Derivative Liabilities
Total gross derivatives	293	106
Exchange- Traded | Other derivatives | Equity
Derivative Assets
Total gross derivatives	60,700	37,737
Derivative Liabilities
Total gross derivatives	59,413	37,349
Exchange- Traded | Other derivatives | Commodity and other
Derivative Assets
Total gross derivatives	2,311	2,353
Derivative Liabilities
Total gross derivatives	$ 2,542	$ 2,830