Stockholders' Equity - Reclassifications from AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Non-interest income (loss)	$ 307	$ 199
Income tax provision (benefit)	302	203
Net income	1,280	960
Interest income (loss)	7,488	7,186
Interest expense	3,689	2,568
Income (loss) from continuing operations before income taxes	1,582	1,163
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income	(177)	(203)
Securities Available for Sale | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Non-interest income (loss)	0	0
Income tax provision (benefit)	0	0
Net income	0	0
Hedging relationships: | Interest rate contracts: | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest income (loss)	(309)	(262)
Hedging relationships: | Foreign exchange and other contracts | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Non-interest income (loss)	74	(8)
Income tax provision (benefit)	(57)	(65)
Net income	(177)	(203)
Interest income (loss)	2	3
Interest expense	(1)	(1)
Income (loss) from continuing operations before income taxes	(234)	(268)
Other: | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax provision (benefit)	0	0
Net income	0	0
Income (loss) from continuing operations before income taxes	$ 0	$ 0