Fair Value - Schedule of Fair Value Measurements, Assets, Using Significant Unobservable Inputs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	$ 127	$ 2,722	$ 16	$ 2,756
Total realized and unrealized gain (losses) recorded in revenue	(5)	(17)	(3)	(6)
Total realized and unrealized gain (losses) recorded in other comprehensive income	0	115	0	(34)
Purchases	2	13	109	194
Sales	0	(19)	0	(61)
Settlements	(1)	(22)	0	(57)
Transfers into Level 3	0	0	15	0
Transfers out of Level 3	(121)	0	(135)	0
Fair value, end of period	2	2,792	2	2,792
Change in unrealized gains (losses) related to financial instruments held	0	(9)	(1)	(3)
Derivative instruments, assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	6	17	2	4
Total realized and unrealized gain (losses) recorded in revenue	(5)	(17)	(3)	(6)
Total realized and unrealized gain (losses) recorded in other comprehensive income	0	0	0	0
Purchases	2	2	3	5
Sales	0	0	0	0
Settlements	(1)	0	0	(1)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair value, end of period	2	2	2	2
Change in unrealized gains (losses) related to financial instruments held	0	(9)	(1)	(3)
Foreign exchange contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	6	17	2	4
Total realized and unrealized gain (losses) recorded in revenue	(5)	(17)	(3)	(6)
Total realized and unrealized gain (losses) recorded in other comprehensive income	0	0	0	0
Purchases	2	2	3	5
Sales	0	0	0	0
Settlements	(1)	0	0	(1)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair value, end of period	2	2	2	2
Change in unrealized gains (losses) related to financial instruments held	0	(9)	(1)	(3)
Asset-backed securities, collateralized loan obligations
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	106	1,841	14	1,820
Total realized and unrealized gain (losses) recorded in revenue	0	0	0	0
Total realized and unrealized gain (losses) recorded in other comprehensive income	0	59	0	(24)
Purchases	0	10	106	188
Sales	0	(19)	0	(61)
Settlements	0	(22)	0	(54)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(106)	0	(120)	0
Fair value, end of period	0	1,869	0	1,869
Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	106	1,841	14	1,820
Total realized and unrealized gain (losses) recorded in revenue	0	0	0	0
Total realized and unrealized gain (losses) recorded in other comprehensive income	0	59	0	(24)
Purchases	0	10	106	188
Sales	0	(19)	0	(61)
Settlements	0	(22)	0	(54)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(106)	0	(120)	0
Fair value, end of period	0	1,869	0	1,869
Other U.S. debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	15		0
Total realized and unrealized gain (losses) recorded in revenue	0		0
Total realized and unrealized gain (losses) recorded in other comprehensive income	0		0
Purchases	0		0
Sales	0		0
Settlements	0		0
Transfers into Level 3	0		15
Transfers out of Level 3	(15)		(15)
Fair value, end of period	0		0
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		820		887
Total realized and unrealized gain (losses) recorded in revenue		0		0
Total realized and unrealized gain (losses) recorded in other comprehensive income		55		(10)
Purchases		1		1
Sales		0		0
Settlements		0		(2)
Transfers into Level 3		0		0
Transfers out of Level 3		0		0
Fair value, end of period		876		876
Non-U.S. debt securities, other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period		44		45
Total realized and unrealized gain (losses) recorded in revenue		0		0
Total realized and unrealized gain (losses) recorded in other comprehensive income		1		0
Purchases		0		0
Sales		0		0
Settlements		0		0
Transfers into Level 3		0		0
Transfers out of Level 3		0		0
Fair value, end of period		45		45
Total non-U.S. debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period		864		932
Total realized and unrealized gain (losses) recorded in revenue		0		0
Total realized and unrealized gain (losses) recorded in other comprehensive income		56		(10)
Purchases		1		1
Sales		0		0
Settlements		0		(2)
Transfers into Level 3		0		0
Transfers out of Level 3		0		0
Fair value, end of period		921		921
Investment securities available-for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	121	2,705	14	2,752
Total realized and unrealized gain (losses) recorded in revenue	0	0	0	0
Total realized and unrealized gain (losses) recorded in other comprehensive income	0	115	0	(34)
Purchases	0	11	106	189
Sales	0	(19)	0	(61)
Settlements	0	(22)	0	(56)
Transfers into Level 3	0	0	15	0
Transfers out of Level 3	(121)	0	(135)	0
Fair value, end of period	$ 0	$ 2,790	$ 0	$ 2,790