Fair Value - Schedule of Fair Value Measurements, Assets, Using Significant Unobservable Inputs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	$ 16	$ 2,756
Total realized and unrealized gain (losses) recorded in revenue	0	11
Total realized and unrealized gain (losses) recorded in other comprehensive income	0	(149)
Purchases	110	181
Sales	0	(42)
Settlements	0	(35)
Transfers into Level 3	15	0
Transfers out of Level 3	(14)	0
Fair value, end of period	127	2,722
Change in unrealized gains (losses) related to financial instruments held	1	12
Derivative instruments, assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	2	4
Total realized and unrealized gain (losses) recorded in revenue	0	11
Total realized and unrealized gain (losses) recorded in other comprehensive income	0	0
Purchases	4	3
Sales	0	0
Settlements	0	(1)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair value, end of period	6	17
Change in unrealized gains (losses) related to financial instruments held	1	12
Foreign exchange contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	2	4
Total realized and unrealized gain (losses) recorded in revenue	0	11
Total realized and unrealized gain (losses) recorded in other comprehensive income	0	0
Purchases	4	3
Sales	0	0
Settlements	0	(1)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair value, end of period	6	17
Change in unrealized gains (losses) related to financial instruments held	1	12
Asset-backed securities, collateralized loan obligations
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	14	1,820
Total realized and unrealized gain (losses) recorded in revenue	0	0
Total realized and unrealized gain (losses) recorded in other comprehensive income	0	(83)
Purchases	106	178
Sales	0	(42)
Settlements	0	(32)
Transfers into Level 3	0	0
Transfers out of Level 3	(14)	0
Fair value, end of period	106	1,841
Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	14	1,820
Total realized and unrealized gain (losses) recorded in revenue	0	0
Total realized and unrealized gain (losses) recorded in other comprehensive income	0	(83)
Purchases	106	178
Sales	0	(42)
Settlements	0	(32)
Transfers into Level 3	0	0
Transfers out of Level 3	(14)	0
Fair value, end of period	106	1,841
Other U.S. debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period
Total realized and unrealized gain (losses) recorded in revenue	0
Total realized and unrealized gain (losses) recorded in other comprehensive income	0
Purchases	0
Sales	0
Settlements	0
Transfers into Level 3	15
Transfers out of Level 3	0
Fair value, end of period	15
Non-U.S. debt securities, asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period		887
Total realized and unrealized gain (losses) recorded in revenue		0
Total realized and unrealized gain (losses) recorded in other comprehensive income		(65)
Purchases		0
Sales		0
Settlements		(2)
Transfers into Level 3		0
Transfers out of Level 3		0
Fair value, end of period		820
Non-U.S. debt securities, other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period		45
Total realized and unrealized gain (losses) recorded in revenue		0
Total realized and unrealized gain (losses) recorded in other comprehensive income		(1)
Purchases		0
Sales		0
Settlements		0
Transfers into Level 3		0
Transfers out of Level 3		0
Fair value, end of period		44
Total non-U.S. debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period		932
Total realized and unrealized gain (losses) recorded in revenue		0
Total realized and unrealized gain (losses) recorded in other comprehensive income		(66)
Purchases		0
Sales		0
Settlements		(2)
Transfers into Level 3		0
Transfers out of Level 3		0
Fair value, end of period		864
Investment securities available-for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	14	2,752
Total realized and unrealized gain (losses) recorded in revenue	0	0
Total realized and unrealized gain (losses) recorded in other comprehensive income	0	(149)
Purchases	106	178
Sales	0	(42)
Settlements	0	(34)
Transfers into Level 3	15	0
Transfers out of Level 3	(14)	0
Fair value, end of period	$ 121	$ 2,705