Stockholders' Equity - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance			$ 3,494
Other comprehensive income (loss), net of tax	$ 9	$ 302	(1,702)	$ 2,833
AOCI ending balance	1,792		1,792
Securities available for sale
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	1,038	2,151	2,186	935
Other comprehensive income (loss) before reclassifications	51	222	(1,094)	1,446
Amounts reclassified from AOCI into earnings	0	0	(3)	0
Other comprehensive income (loss), net of tax	51	222	(1,097)	1,446
AOCI ending balance	1,089	2,373	1,089	2,373
Hedging Relationships
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	781	1,728	1,362	354
Other comprehensive income (loss) before reclassifications	193	(60)	(145)	1,635
Amounts reclassified from AOCI into earnings	(244)	117	(487)	(204)
Other comprehensive income (loss), net of tax	(51)	57	(632)	1,431
AOCI ending balance	730	1,785	730	1,785
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	(12)	(174)	(31)	(107)
Other comprehensive income (loss) before reclassifications	9	23	28	(44)
Amounts reclassified from AOCI into earnings	0	0	0	0
Other comprehensive income (loss), net of tax	9	23	28	(44)
AOCI ending balance	(3)	(151)	(3)	(151)
Other
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	(24)	(26)	(23)	(26)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from AOCI into earnings	0	0	(1)	0
Other comprehensive income (loss), net of tax	0	0	(1)	0
AOCI ending balance	(24)	(26)	(24)	(26)
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	1,783	3,679	3,494	1,156
Other comprehensive income (loss) before reclassifications	253	185	(1,211)	3,037
Amounts reclassified from AOCI into earnings	(244)	117	(491)	(204)
Other comprehensive income (loss), net of tax	9	302	(1,702)	2,833
AOCI ending balance	1,792	3,981	1,792	3,981
Net investment hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Other comprehensive gain (loss)	$ (13)	$ (8)	$ (34)	134
Cumulative effects from adoption of new accounting standards | Securities available for sale
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance				(8)
Cumulative effects from adoption of new accounting standards | Hedging Relationships
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance				0
Cumulative effects from adoption of new accounting standards | Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance				0
Cumulative effects from adoption of new accounting standards | Other
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance				0
Cumulative effects from adoption of new accounting standards | Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance				$ (8)