Investment Securities - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2024 USD ($) Security	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Summary of Investment Holdings [Line Items]
Gross realized gains(loss) on sale of investment securities	$ 0	$ 0
Gains (losses) on equity securities	$ 2,000,000
Number of debt securities with aggregate gross unrealized losses | Security	4,088
Unrealized losses on individual debt securities	$ (1,500,000,000)
Cost method equity securities	928,000,000
Investment securities pledged to secure debt carrying value	9,600,000,000		$ 8,200,000,000
Carrying value of investment securities pledged related to repurchase transactions	357,000,000		393,000,000
Available-for-Sale Securities [Member]
Summary of Investment Holdings [Line Items]
Allowance for credit losses	$ 0		$ 0