Investment Securities - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) security	Sep. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Percentage of investment portfolio considered investment grade	99.00%		99.00%
Allowance for credit losses on HTM investment securities	$ 1,000,000		$ 1,000,000		$ 0	$ 0
Allowance for credit losses on available-for-sale securities	0	$ 1,000,000	0	$ 1,000,000	$ 0	2,000,000	$ 2,000,000	$ 2,000,000
Provision	0	(1,000,000)	(2,000,000)	(1,000,000)
Charge-offs	0	0	0	0
Marketable securities, unrealized gain (loss)			$ (8,710,000,000)
Number of securities in loss position | security			2,031
Proceeds from sales of available-for-sale securities	3,870,000,000		$ 4,567,000,000	4,545,000,000
Gains (losses) from sales of available-for-sale securities, net	294,000,000	$ 0	294,000,000	$ 2,000,000
Asset pledged as collateral
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Debt securities	$ 79,740,000,000		$ 79,740,000,000			$ 70,520,000,000