Investment Securities - Gross Unrealized Losses and Fair Value, Aggregated by Investment Category (Detail) $ in Thousands	Jun. 30, 2021 USD ($)
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	$ 561,329
Less than 12 Months, Unrealized Losses	(4,395)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	561,329
Unrealized Losses	(4,395)
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	61,515
Less than 12 Months, Unrealized Losses	(377)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	61,515
Unrealized Losses	(377)
Agency-guaranteed residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	10,355
Less than 12 Months, Unrealized Losses	(265)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	10,355
Unrealized Losses	(265)
Agency-guaranteed commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	2,205
Less than 12 Months, Unrealized Losses	(1)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	2,205
Unrealized Losses	(1)
Agency-guaranteed residential collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	18,158
Less than 12 Months, Unrealized Losses	(62)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	18,158
Unrealized Losses	(62)
Agency-guaranteed commercial collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	142,841
Less than 12 Months, Unrealized Losses	(1,752)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	142,841
Unrealized Losses	(1,752)
Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	101,555
Less than 12 Months, Unrealized Losses	(181)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	101,555
Unrealized Losses	(181)
Corporate notes
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	67,230
Less than 12 Months, Unrealized Losses	(462)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	67,230
Unrealized Losses	(462)
Private label collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	157,470
Less than 12 Months, Unrealized Losses	(1,295)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	157,470
Unrealized Losses	$ (1,295)

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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