Stockholders' Equity - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	$ 374
Other comprehensive income (loss), net of tax	(4,467)	$ (1,711)
AOCI ending balance	(4,093)
Securities available for sale | Available-for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	297	2,186
Other comprehensive income (loss) before reclassifications	(3,253)	(1,145)
Amounts reclassified from AOCI into earnings	0	(3)
Other comprehensive income (loss), net of tax	(3,253)	(1,148)
AOCI ending balance	(2,956)	1,038
Hedging Relationships
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	118	1,362
Other comprehensive income (loss) before reclassifications	(1,123)	(338)
Amounts reclassified from AOCI into earnings	(86)	(243)
Other comprehensive income (loss), net of tax	(1,209)	(581)
AOCI ending balance	(1,091)	781
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	(21)	(31)
Other comprehensive income (loss) before reclassifications	(5)	19
Amounts reclassified from AOCI into earnings	0	0
Other comprehensive income (loss), net of tax	(5)	19
AOCI ending balance	(26)	(12)
Other
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	(20)	(23)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from AOCI into earnings	0	(1)
Other comprehensive income (loss), net of tax	0	(1)
AOCI ending balance	(20)	(24)
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI beginning balance	374	3,494
Other comprehensive income (loss) before reclassifications	(4,381)	(1,464)
Amounts reclassified from AOCI into earnings	(86)	(247)
Other comprehensive income (loss), net of tax	(4,467)	(1,711)
AOCI ending balance	(4,093)	1,783
Net investment hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Other comprehensive gain (loss)	$ 48	$ (21)