Amount of 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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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

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Investment Securities (Narrative) (Detail) - USD ($)	3 Months Ended		9 Months Ended
Investment Securities (Narrative) (Detail) - USD ($)	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Proceeds from Sale of Available-for-sale Securities			$ 8,963,000	$ 0
Available-for-sale Securities, Gross Realized Gains			8,000	0
Investment securities available-for-sale, at fair value	$ 3,304,217,000		3,304,217,000		$ 2,925,833,000
Pledged Financial Instruments, Not Separately Reported, Securities	4,000,000,000.0		4,000,000,000.0		2,700,000,000
Corporate Debt Securities [Member]
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Proceeds from Sale of Available-for-sale Securities	0	$ 0	9,000,000.0	$ 0
Investment securities available-for-sale, at fair value	12,453,000		12,453,000		$ 22,240,000
Callable [Member]
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Investment securities available-for-sale, at fair value	$ 1,300,000,000		$ 1,300,000,000