Derivative Instruments and Hedging Activities - Derivative Assets and Liabilities at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Notional or contractual amount	$ 274,925	$ 227,801
Derivative assets, gross amount	3,381	3,098
Derivative liabilities, gross amount	3,699	4,550
Derivative asset, netting adjustments	(1,471)	(1,134)
Derivative liability, netting adjustments	(632)	(1,235)
Total derivative assets	1,910	1,964
Total derivative liabilities	3,067	3,315
Net valuation allowance on derivative assets and liabilities for non-performance risk	1	4
Derivatives designated as accounting hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	136,569	98,966
Derivative assets, gross amount	307	85
Derivative liabilities, gross amount	307	820
Derivatives designated as accounting hedges | Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional or contractual amount	128,273	91,306
Derivative assets, gross amount	157	3
Derivative liabilities, gross amount	20	504
Derivatives designated as accounting hedges | Interest rate contracts | Fair value hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	67,173	60,956
Derivative assets, gross amount	40	3
Derivative liabilities, gross amount	10	53
Derivatives designated as accounting hedges | Interest rate contracts | Cash flow hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	61,100	30,350
Derivative assets, gross amount	117	0
Derivative liabilities, gross amount	10	451
Derivatives designated as accounting hedges | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional or contractual amount	8,296	7,660
Derivative assets, gross amount	150	82
Derivative liabilities, gross amount	287	316
Derivatives designated as accounting hedges | Foreign exchange contracts | Fair value hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	1,322	1,338
Derivative assets, gross amount	0	0
Derivative liabilities, gross amount	208	211
Derivatives designated as accounting hedges | Foreign exchange contracts | Cash flow hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	2,356	2,175
Derivative assets, gross amount	69	4
Derivative liabilities, gross amount	1	14
Derivatives designated as accounting hedges | Foreign exchange contracts | Net investment hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	4,618	4,147
Derivative assets, gross amount	81	78
Derivative liabilities, gross amount	78	91
Derivatives not designated as accounting hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	138,356	128,835
Derivative assets, gross amount	3,074	3,013
Derivative liabilities, gross amount	3,392	3,730
Derivatives not designated as accounting hedges | Customer accommodation
Derivatives, Fair Value [Line Items]
Notional or contractual amount	134,898	125,462
Derivative assets, gross amount	3,031	2,970
Derivative liabilities, gross amount	3,363	3,689
Derivatives not designated as accounting hedges | Interest rate contracts | Customer accommodation
Derivatives, Fair Value [Line Items]
Notional or contractual amount	98,191	91,601
Derivative assets, gross amount	1,609	1,140
Derivative liabilities, gross amount	1,986	1,873
Derivatives not designated as accounting hedges | Interest rate contracts | Other interest rate exposures
Derivatives, Fair Value [Line Items]
Notional or contractual amount	743	1,135
Derivative assets, gross amount	27	34
Derivative liabilities, gross amount	19	22
Derivatives not designated as accounting hedges | Foreign exchange contracts | Customer accommodation
Derivatives, Fair Value [Line Items]
Notional or contractual amount	4,576	4,926
Derivative assets, gross amount	68	74
Derivative liabilities, gross amount	42	78
Derivatives not designated as accounting hedges | Commodity contracts | Customer accommodation
Derivatives, Fair Value [Line Items]
Notional or contractual amount	32,131	28,935
Derivative assets, gross amount	1,354	1,756
Derivative liabilities, gross amount	1,335	1,738
Derivatives not designated as accounting hedges | Other contracts
Derivatives, Fair Value [Line Items]
Notional or contractual amount	2,715	2,238
Derivative assets, gross amount	16	9
Derivative liabilities, gross amount	$ 10	$ 19