Derivative Instruments and Hedging Activities - Derivative Assets and Liabilities at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Notional or contractual amount	$ 224,374	$ 213,069
Derivative assets, gross amount	4,519	2,690
Derivative liabilities, gross amount	(4,853)	(1,868)
Derivative asset, netting adjustments	(761)	(542)
Derivative liability, netting adjustments	(1,282)	(544)
Total derivative assets	3,758	2,148
Total derivative liabilities	3,571	1,324
Net valuation allowance on derivative assets and liabilities for non-performance risk	10	11
Derivatives designated as accounting hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	112,592	111,618
Derivative assets, gross amount	161	326
Derivative liabilities, gross amount	(265)	(39)
Derivatives designated as accounting hedges | Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional or contractual amount	104,565	102,059
Derivative assets, gross amount	32	246
Derivative liabilities, gross amount	(157)	(19)
Derivatives designated as accounting hedges | Interest rate contracts | Fair value hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	50,665	49,659
Derivative assets, gross amount	7	2
Derivative liabilities, gross amount	(6)	(3)
Derivatives designated as accounting hedges | Interest rate contracts | Cash flow hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	53,900	52,400
Derivative assets, gross amount	25	244
Derivative liabilities, gross amount	(151)	(16)
Derivatives designated as accounting hedges | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional or contractual amount	8,027	9,559
Derivative assets, gross amount	129	80
Derivative liabilities, gross amount	(108)	(20)
Derivatives designated as accounting hedges | Foreign exchange contracts | Fair value hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	1,383	1,421
Derivative assets, gross amount	0	13
Derivative liabilities, gross amount	(67)	0
Derivatives designated as accounting hedges | Foreign exchange contracts | Cash flow hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	3,145	4,679
Derivative assets, gross amount	19	24
Derivative liabilities, gross amount	(28)	(20)
Derivatives designated as accounting hedges | Foreign exchange contracts | Net investment hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	3,499	3,459
Derivative assets, gross amount	110	43
Derivative liabilities, gross amount	(13)	0
Derivatives not designated as accounting hedges
Derivatives, Fair Value [Line Items]
Notional or contractual amount	111,782	101,451
Derivative assets, gross amount	4,358	2,364
Derivative liabilities, gross amount	(4,588)	(1,829)
Derivatives not designated as accounting hedges | Customer accommodation
Derivatives, Fair Value [Line Items]
Notional or contractual amount	106,814	97,524
Derivative assets, gross amount	4,300	2,329
Derivative liabilities, gross amount	(4,570)	(1,797)
Derivatives not designated as accounting hedges | Interest rate contracts | Customer accommodation
Derivatives, Fair Value [Line Items]
Notional or contractual amount	77,158	71,724
Derivative assets, gross amount	355	620
Derivative liabilities, gross amount	(777)	(194)
Derivatives not designated as accounting hedges | Interest rate contracts | Other interest rate exposures
Derivatives, Fair Value [Line Items]
Notional or contractual amount	2,871	1,899
Derivative assets, gross amount	55	33
Derivative liabilities, gross amount	(23)	(25)
Derivatives not designated as accounting hedges | Foreign exchange contracts | Customer accommodation
Derivatives, Fair Value [Line Items]
Notional or contractual amount	4,271	3,779
Derivative assets, gross amount	55	40
Derivative liabilities, gross amount	(47)	(42)
Derivatives not designated as accounting hedges | Commodity contracts | Customer accommodation
Derivatives, Fair Value [Line Items]
Notional or contractual amount	25,385	22,021
Derivative assets, gross amount	3,890	1,669
Derivative liabilities, gross amount	(3,746)	(1,561)
Derivatives not designated as accounting hedges | Other contracts
Derivatives, Fair Value [Line Items]
Notional or contractual amount	2,097	2,028
Derivative assets, gross amount	3	2
Derivative liabilities, gross amount	$ (5)	$ (7)