Derivative Financial Instruments - Summary of Derivative Activity and Related Impact on Consolidated Statements of Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest rate risks | Derivatives designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	$ 62	$ 50	$ (5)
Interest rate risks | Derivatives designated as hedging instruments | Amounts reclassified from AOCI into income | Interest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	63	50	(5)
Interest rate risks | Derivatives designated as hedging instruments | Change in fair value of interest rate swaps hedging investment securities | Interest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	138	0	0
Interest rate risks | Derivatives designated as hedging instruments | Change in fair value of hedged investment securities | Interest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	(139)	0	0
Foreign exchange forward and option contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	0	(1)	(1)
Foreign exchange forward and option contracts | Derivatives not designated as hedging instruments | Gains (losses) on revaluations of internal foreign currency instruments, net | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	(43)	39	1
Foreign exchange forward and option contracts | Derivatives not designated as hedging instruments | Gains (losses) on client foreign exchange forward contracts, net | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	43	(40)	(2)
Other derivative instruments | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	0	0	1
Other derivative instruments | Derivatives not designated as hedging instruments | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	2	28	(1)
Other derivative instruments | Derivatives not designated as hedging instruments | Gains (losses) on revaluations of internal foreign currency instruments, net | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	17	3	(15)
Other derivative instruments | Derivatives not designated as hedging instruments | Gains (losses) on client foreign exchange forward contracts, net | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	(17)	(3)	16
Equity warrant assets
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) on derivatives	26	2	(2)
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	$ 560	$ 237	$ 138