Investment Securities (Schedule of Realized Gain (Loss)) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Realized gains on investment securities	$ 355	$ 78	$ 1,184	$ 725
Realized losses on investment securities	(5)	(28)	(40)	(525)
Net realized gains on investment securities	350	50	1,144	200
Unrealized gains on equity securities with readily determinable fair value	1	471	2,627	2,118
Unrealized losses on equity securities with readily determinable fair value	(634)	(110)	(1,585)	(3,766)
Net unrealized (losses) gains on equity securities with readily determinable fair value	(633)	361	1,042	(1,648)
Upward adjustments of equity securities without readily determinable fair values	0	0	0	393
Downward adjustments of equity securities without readily determinable fair values	0	0	0	0
Impairment of equity securities without readily determinable fair values	(2,148)	0	(2,178)	(2,085)
Adjustment and impairment, net, of equity securities without readily determinable fair values	(2,148)	0	(2,178)	(1,692)
(Losses) gains on investment securities, net	(2,431)	411	8	(3,140)
Proceeds from sales of available-for-sale securities	189,851	0	192,227	502,676
Proceeds from sales of equity securities with readily determinable fair value	3,500	2,500	9,759	6,530
Proceeds from sales and capital distributions of equity securities without readily determinable fair value	$ 1,330	$ 1,247	$ 2,467	$ 1,691