Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without an allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Investment Securities - Additional Information (Detail) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jun. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 security	Sep. 30, 2021 contract	Dec. 31, 2020 USD ($) security
Investments, Debt and Equity Securities [Abstract]
Proceeds from sales of foreign subsidiaries				$ 3,765	$ 0
Loss on sale of foreign subsidiaries	$ (2,800)	$ 0	$ 0	(2,840)	0
Unrealized gain (loss) on investment securities			200	2,700	(100)
Proceeds from sales of investment securities available for sale		258,400	268,600	666,023	377,767
Realized gain		6,100	$ 11,700	31,400	$ 20,000
Number of available-for-sale investment securities, unrealized loss position, less than twelve month category \| security						35
Number of available-for-sale investment securities, unrealized loss position, twelve month or more category \| contract							1
Number of available-for-sale investment securities, unrealized loss position						36	36	16
Pledged investment securities fair value		$ 12,400		$ 12,400				$ 18,800