Investment Securities - Gross Unrealized Losses and Fair Value, Aggregated by Investment Category (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	$ 2,024,753	$ 135,579
Less Than 12 Months, Unrealized Losses	(15,567)	(647)
12 Months or More, Fair Value	6,818	0
12 Months or More, Unrealized Losses	(136)	0
Fair Value	2,031,571	135,579
Unrealized Losses	(15,703)	(647)
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	54,753	42,588
Less Than 12 Months, Unrealized Losses	(119)	(10)
12 Months or More, Fair Value	0	0
12 Months or More, Unrealized Losses	0	0
Fair Value	54,753	42,588
Unrealized Losses	(119)	(10)
Agency-guaranteed residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	9,554
Less Than 12 Months, Unrealized Losses	(312)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value	9,554
Unrealized Losses	(312)
Agency-guaranteed commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	2,152
Less Than 12 Months, Unrealized Losses	(10)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value	2,152
Unrealized Losses	(10)
Agency-guaranteed residential collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	173,492	8,896
Less Than 12 Months, Unrealized Losses	(2,315)	(60)
12 Months or More, Fair Value	0	0
12 Months or More, Unrealized Losses	0	0
Fair Value	173,492	8,896
Unrealized Losses	(2,315)	(60)
Agency-guaranteed commercial collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	118,334	20,926
Less Than 12 Months, Unrealized Losses	(3,877)	(39)
12 Months or More, Fair Value	0	0
12 Months or More, Unrealized Losses	0	0
Fair Value	118,334	20,926
Unrealized Losses	(3,877)	(39)
Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	715,250
Less Than 12 Months, Unrealized Losses	(1,215)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value	715,250
Unrealized Losses	(1,215)
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	122,597
Less Than 12 Months, Unrealized Losses	(180)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value	122,597
Unrealized Losses	(180)
Corporate notes
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	188,100	50,620
Less Than 12 Months, Unrealized Losses	(1,561)	(164)
12 Months or More, Fair Value		0
12 Months or More, Unrealized Losses		0
Fair Value	188,100	50,620
Unrealized Losses	(1,561)	(164)
Private label collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	632,091	12,549
Less Than 12 Months, Unrealized Losses	(5,874)	(374)
12 Months or More, Fair Value	6,818	0
12 Months or More, Unrealized Losses	(136)	0
Fair Value	638,909	12,549
Unrealized Losses	(6,010)	$ (374)
State and political subdivision debt securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	8,430
Less Than 12 Months, Unrealized Losses	(104)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value	8,430
Unrealized Losses	$ (104)

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value

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Amount of accumulated unrealized loss on 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 12 months or longer, 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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