Derivative Financial Instruments - Summary of Derivative Activity and Related Impact on Consolidated Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	$ (104)	$ (14)
Interest rate risks | Derivatives designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	14	17
Interest rate risks | Derivatives designated as hedging instruments | Reclassification out of Accumulated Other Comprehensive Income | Interest income - loans
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	15	16
Interest rate risks | Derivatives designated as hedging instruments | Change In Fair Value Of Interest Rate Swaps Hedging Investment Securities | Interest income - loans
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	330	18
Interest rate risks | Derivatives designated as hedging instruments | Change In Fair Value Of Hedged Investment Securities | Interest income - loans
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	(331)	(17)
Currency exchange risk | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	3	(1)
Currency exchange risk | Derivatives not designated as hedging instruments | Revaluations of internal foreign currency instruments, net | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	2	(28)
Currency exchange risk | Derivatives not designated as hedging instruments | Foreign exchange forward contracts, net | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	1	27
Other derivative instruments | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	(3)	0
Other derivative instruments | Derivatives not designated as hedging instruments | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	3	5
Other derivative instruments | Derivatives not designated as hedging instruments | Revaluations of internal foreign currency instruments, net | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	(5)	(3)
Other derivative instruments | Derivatives not designated as hedging instruments | Foreign exchange forward contracts, net | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	2	3
Equity warrant assets | Derivatives not designated as hedging instruments | Gains on equity warrant assets, net
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	63	222
Total return swaps | Derivatives not designated as hedging instruments | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	$ (8)	$ 0