Investment Securities - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($) Security	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) Security	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Summary of Investment Holdings [Line Items]
Gross realized gains(loss) on sale of investment securities	$ 0	$ 0	$ 0	$ 0
Gains (losses) on equity securities	$ 1,004,000	$ (62,000)	$ 588,000	$ (805,000)
Number of debt securities with aggregate gross unrealized losses | Security	4,281		4,281
Unrealized losses on individual debt securities			$ (1,700,000,000)
Cost method equity securities	$ 973,000,000		973,000,000
Investment securities pledged to secure debt carrying value	6,900,000,000		6,900,000,000		$ 7,900,000,000
Carrying value of investment securities pledged related to repurchase transactions	548,000,000		548,000,000		567,000,000
Available-for-Sale Securities [Member]
Summary of Investment Holdings [Line Items]
Allowance for credit losses	$ 0		$ 0		$ 0