Derivative Instruments and Hedging Activities - Derivative Assets and Liabilities at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	$ 294,039	$ 227,801
Derivative assets, gross amount	2,675	3,098
Derivative liabilities, gross amount	2,932	4,550
Derivative Asset, netting adjustments	(1,005)	(1,134)
Derivative Liability, netting adjustments	(597)	(1,235)
Net Amounts as Recognized	1,670	1,964
Net Amounts as Recognized	2,335	3,315
Net valuation allowance on derivative assets and liabilities for non-performance risk	2	4
Derivatives designated as accounting hedges:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	148,075	98,966
Derivative assets, gross amount	235	85
Derivative liabilities, gross amount	317	820
Derivatives designated as accounting hedges: | Interest rate contracts:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	139,337	91,306
Derivative assets, gross amount	234	3
Derivative liabilities, gross amount	49	504
Derivatives designated as accounting hedges: | Interest rate contracts: | Fair value hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	68,987	60,956
Derivative assets, gross amount	18	3
Derivative liabilities, gross amount	26	53
Derivatives designated as accounting hedges: | Interest rate contracts: | Cash flow hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	70,350	30,350
Derivative assets, gross amount	216	0
Derivative liabilities, gross amount	23	451
Derivatives designated as accounting hedges: | Foreign exchange and other contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	8,738	7,660
Derivative assets, gross amount	1	82
Derivative liabilities, gross amount	268	316
Derivatives designated as accounting hedges: | Foreign exchange and other contracts | Fair value hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	1,380	1,338
Derivative assets, gross amount	0	0
Derivative liabilities, gross amount	113	211
Derivatives designated as accounting hedges: | Foreign exchange and other contracts | Cash flow hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	2,488	2,175
Derivative assets, gross amount	0	4
Derivative liabilities, gross amount	66	14
Derivatives designated as accounting hedges: | Foreign exchange and other contracts | Net investment hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	4,870	4,147
Derivative assets, gross amount	1	78
Derivative liabilities, gross amount	89	91
Derivatives not designated as accounting hedges:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	145,964	128,835
Derivative assets, gross amount	2,440	3,013
Derivative liabilities, gross amount	2,615	3,730
Derivatives not designated as accounting hedges: | Customer accommodation:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	142,137	125,462
Derivative assets, gross amount	2,399	2,970
Derivative liabilities, gross amount	2,576	3,689
Derivatives not designated as accounting hedges: | Interest rate contracts: | Customer accommodation:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	103,489	91,601
Derivative assets, gross amount	1,188	1,140
Derivative liabilities, gross amount	1,382	1,873
Derivatives not designated as accounting hedges: | Interest rate contracts: | Other interest rate exposures
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	872	1,135
Derivative assets, gross amount	21	34
Derivative liabilities, gross amount	31	22
Derivatives not designated as accounting hedges: | Foreign exchange and other contracts | Customer accommodation:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	5,153	4,926
Derivative assets, gross amount	50	74
Derivative liabilities, gross amount	47	78
Derivatives not designated as accounting hedges: | Commodity contracts | Customer accommodation:
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	33,495	28,935
Derivative assets, gross amount	1,161	1,756
Derivative liabilities, gross amount	1,147	1,738
Derivatives not designated as accounting hedges: | Other contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	2,955	2,238
Derivative assets, gross amount	20	9
Derivative liabilities, gross amount	$ 8	$ 19