Derivative Financial Instruments - Carrying Value of Hedged Items in Fair Value Hedge (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Carrying amount of hedged items	$ 11,112	$ 15,034
Active hedged asset adjustments	(1,320)	(1,633)
Discontinued hedged asset adjustments	(70)	246
Total hedged asset adjustments	$ (1,390)	$ (1,387)
Hedged Asset, Statement of Financial Position [Extensible Enumeration]	Securities available-for-sale (includes amortized cost of $28.0 billion and $30.3 billion at December 31, 2023 and 2022, respectively, an allowance for credit losses of nil at both December 31, 2023 and 2022, and $161 million and $55 million pledged to creditors at December 31, 2023 and 2022, respectively)	Securities available-for-sale (includes amortized cost of $28.0 billion and $30.3 billion at December 31, 2023 and 2022, respectively, an allowance for credit losses of nil at both December 31, 2023 and 2022, and $161 million and $55 million pledged to creditors at December 31, 2023 and 2022, respectively)
Deposits
Derivatives, Fair Value [Line Items]
Carrying amount of hedged liability items	$ 1,463	$ 1,446
Active hedged liability adjustments	(104)	(150)
Discontinued hedged liability adjustments	67	96
Total hedged liability adjustments	$ (37)	$ (54)
Hedged Liability, Statement of Financial Position [Extensible Enumeration]	Deposits	Deposits
Long-term debt
Derivatives, Fair Value [Line Items]
Carrying amount of hedged liability items	$ 7,913	$ 6,506
Active hedged liability adjustments	(407)	(605)
Discontinued hedged liability adjustments	72	111
Total hedged liability adjustments	$ (335)	$ (494)
Hedged Liability, Statement of Financial Position [Extensible Enumeration]	Long-term debt (includes $7.5 billion and $8.4 billion designated under fair value option at December 31, 2023 and 2022, respectively)	Long-term debt (includes $7.5 billion and $8.4 billion designated under fair value option at December 31, 2023 and 2022, respectively)