Investment Securities (Narrative) (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($) security	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) security	Jun. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Investments, Debt and Equity Securities [Abstract]
Equity securities without readily determinable fair value	$ 42,100,000		$ 42,100,000
Upward adjustments of equity securities without readily determinable fair values	0	$ 0	0	$ 0
Downward adjustments of equity securities without readily determinable fair values	0	0	0	0
Impairment of equity securities without readily determinable fair values	3,786,000	0	4,357,000	30,000
Pledged securities	$ 2,800,000,000	$ 2,400,000,000	$ 2,800,000,000	$ 2,400,000,000	$ 2,600,000,000
Number of securities by a single non-government sponsored issuer exceeding 10% of shareholders' equity | security	0		0