Stockholders' Equity - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance			$ 3,494
Other comprehensive income (loss), net of tax	$ (432)	$ (148)	(2,134)	$ 2,685
AOCI ending balance	1,360		1,360
Securities available for sale
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	1,089	2,373	2,186	935
Other comprehensive income (loss) before reclassifications	(206)	20	(1,300)	1,466
Amounts reclassified from AOCI into earnings	(2)	(19)	(5)	(19)
Other comprehensive income (loss), net of tax	(208)	1	(1,305)	1,447
AOCI ending balance	881	2,374	881	2,374
Hedging Relationships
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	730	1,785	1,362	354
Other comprehensive income (loss) before reclassifications	57	(95)	(88)	1,540
Amounts reclassified from AOCI into earnings	(252)	(80)	(739)	(284)
Other comprehensive income (loss), net of tax	(195)	(175)	(827)	1,256
AOCI ending balance	535	1,610	535	1,610
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	(3)	(151)	(31)	(107)
Other comprehensive income (loss) before reclassifications	(27)	28	1	(16)
Amounts reclassified from AOCI into earnings	0	0	0	0
Other comprehensive income (loss), net of tax	(27)	28	1	(16)
AOCI ending balance	(30)	(123)	(30)	(123)
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	(2)	(2)	(3)	(2)
Other comprehensive income (loss), net of tax	(2)	(2)	(3)	(2)
AOCI ending balance	(26)	(28)	(26)	(28)
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	1,792	3,981	3,494	1,156
Other comprehensive income (loss) before reclassifications	(176)	(47)	(1,387)	2,990
Amounts reclassified from AOCI into earnings	(256)	(101)	(747)	(305)
Other comprehensive income (loss), net of tax	(432)	(148)	(2,134)	2,685
AOCI ending balance	1,360	3,833	1,360	3,833
Net investment hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Other comprehensive gain (loss)	$ 66	$ (75)	$ 32	59
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)