Derivative Instruments and Hedging Activities - Derivative Assets and Liabilities at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	$ 306,504	$ 294,039
Derivative assets, gross amount	2,456	2,675
Derivative liabilities, gross amount	2,773	2,932
Derivative Asset, netting adjustments	(1,034)	(1,005)
Derivative Liability, netting adjustments	(371)	(597)
Net Amounts as Recognized	1,422	1,670
Net Amounts as Recognized	2,402	2,335
Net valuation allowance on derivative assets and liabilities for non-performance risk	3	2
Derivatives designated as accounting hedges:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	159,896	148,075
Derivative assets, gross amount	192	235
Derivative liabilities, gross amount	344	317
Derivatives designated as accounting hedges: | Interest rate contracts:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	151,966	139,337
Derivative assets, gross amount	152	234
Derivative liabilities, gross amount	201	49
Derivatives designated as accounting hedges: | Interest rate contracts: | Fair value hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	65,916	68,987
Derivative assets, gross amount	11	18
Derivative liabilities, gross amount	101	26
Derivatives designated as accounting hedges: | Interest rate contracts: | Cash flow hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	86,050	70,350
Derivative assets, gross amount	141	216
Derivative liabilities, gross amount	100	23
Derivatives designated as accounting hedges: | Foreign exchange and other contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	7,930	8,738
Derivative assets, gross amount	40	1
Derivative liabilities, gross amount	143	268
Derivatives designated as accounting hedges: | Foreign exchange and other contracts | Fair value hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	536	1,380
Derivative assets, gross amount	0	0
Derivative liabilities, gross amount	106	113
Derivatives designated as accounting hedges: | Foreign exchange and other contracts | Cash flow hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	2,519	2,488
Derivative assets, gross amount	5	0
Derivative liabilities, gross amount	12	66
Derivatives designated as accounting hedges: | Foreign exchange and other contracts | Net investment hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	4,875	4,870
Derivative assets, gross amount	35	1
Derivative liabilities, gross amount	25	89
Derivatives not designated as accounting hedges:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	146,608	145,964
Derivative assets, gross amount	2,264	2,440
Derivative liabilities, gross amount	2,429	2,615
Derivatives not designated as accounting hedges: | Customer accommodation:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	142,502	142,137
Derivative assets, gross amount	2,222	2,399
Derivative liabilities, gross amount	2,409	2,576
Derivatives not designated as accounting hedges: | Interest rate contracts: | Customer accommodation:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	101,533	103,489
Derivative assets, gross amount	1,154	1,188
Derivative liabilities, gross amount	1,382	1,382
Derivatives not designated as accounting hedges: | Interest rate contracts: | Other interest rate exposures
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	1,143	872
Derivative assets, gross amount	20	21
Derivative liabilities, gross amount	12	31
Derivatives not designated as accounting hedges: | Foreign exchange and other contracts | Customer accommodation:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	5,769	5,153
Derivative assets, gross amount	46	50
Derivative liabilities, gross amount	34	47
Derivatives not designated as accounting hedges: | Commodity contracts | Customer accommodation:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	35,200	33,495
Derivative assets, gross amount	1,022	1,161
Derivative liabilities, gross amount	993	1,147
Derivatives not designated as accounting hedges: | Other contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	2,963	2,955
Derivative assets, gross amount	22	20
Derivative liabilities, gross amount	$ 8	$ 8