Investment Securities - Gross Unrealized Losses and Fair Value, Aggregated by Investment Category (Detail) $ in Thousands	Mar. 31, 2020 USD ($)
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	$ 249,946
Less than 12 Months, Unrealized Losses	8,634
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	249,946
Unrealized Losses	8,634
Corporate notes
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months, Fair Value	249,946
Less than 12 Months, Unrealized Losses	8,634
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Fair Value, Total	249,946
Unrealized Losses	$ 8,634

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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