Investment Securities - Gross Unrealized Losses and Fair Value, Aggregated by Investment Category (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	$ 615,410
Less Than 12 Months, Unrealized Losses	(30,300)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	615,410
Unrealized Losses	(30,300)
Agency-guaranteed residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	305,374
Less Than 12 Months, Unrealized Losses	(5,893)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	305,374
Unrealized Losses	(5,893)
Corporate notes
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	310,036
Less Than 12 Months, Unrealized Losses	(24,407)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	310,036
Unrealized Losses	$ (24,407)

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

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- Definition

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.

+ References

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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.

+ References

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+ References

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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 unrealized loss position without allowance for credit loss.

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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 unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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