Investment Securities - Gross Unrealized Losses on Investment Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Debt Securities Available for Sale, Less than 12 months, Fair Value	$ 1,393,098	$ 212,087
Debt Securities Available for Sale, Less than 12 months, Unrealized Loss	(14,640)	(1,332)
Debt Securities Available for Sale, 12 months or more, Fair Value	153,834	297,020
Debt Securities Available for Sale, 12 months or more, Unrealized Loss	(2,165)	(4,710)
Debt Securities Available for Sale, Fair Value	1,546,932	509,107
Debt Securities, Available-for-sale Securities, Unrealized Loss Position, Accumulated Loss	(16,805)	(6,042)
Obligations of U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Debt Securities Available for Sale, Less than 12 months, Fair Value	947,108	160,543
Debt Securities Available for Sale, Less than 12 months, Unrealized Loss	(9,737)	(891)
Debt Securities Available for Sale, 12 months or more, Fair Value	44,086	0
Debt Securities Available for Sale, 12 months or more, Unrealized Loss	(1,293)	0
Debt Securities Available for Sale, Fair Value	991,194	160,543
Debt Securities, Available-for-sale Securities, Unrealized Loss Position, Accumulated Loss	(11,030)	(891)
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Debt Securities Available for Sale, Less than 12 months, Fair Value	56,153	0
Debt Securities Available for Sale, Less than 12 months, Unrealized Loss	(785)	0
Debt Securities Available for Sale, 12 months or more, Fair Value	0	0
Debt Securities Available for Sale, 12 months or more, Unrealized Loss	0	0
Debt Securities Available for Sale, Fair Value	56,153	0
Debt Securities, Available-for-sale Securities, Unrealized Loss Position, Accumulated Loss	(785)	0
Asset backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities Available for Sale, Less than 12 months, Fair Value	389,837	51,544
Debt Securities Available for Sale, Less than 12 months, Unrealized Loss	(4,118)	(441)
Debt Securities Available for Sale, 12 months or more, Fair Value	109,748	297,020
Debt Securities Available for Sale, 12 months or more, Unrealized Loss	(872)	(4,710)
Debt Securities Available for Sale, Fair Value	499,585	348,564
Debt Securities, Available-for-sale Securities, Unrealized Loss Position, Accumulated Loss	$ (4,990)	$ (5,151)

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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