v3.20.2

Investments - Fair Values and Gross Unrealized Losses of Available-for-Sale Securities Aggregated by Investment Category (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Continuous unrealized loss position, less than 12 months, fair value	$ 428,730	$ 280,570
Continuous unrealized loss position, less than 12 months, gross unrealized losses	(529)	(204)
Continuous unrealized loss position, 12 months or greater, fair value	0	16,264
Continuous unrealized loss position, 12 months or greater, gross unrealized loss	0	(15)
Continuous unrealized loss position, fair value	428,730	296,834
Continuous unrealized loss position, gross unrealized losses	(529)	(219)
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Continuous unrealized loss position, less than 12 months, fair value	82,317	20,752
Continuous unrealized loss position, less than 12 months, gross unrealized losses	(31)	(9)
Continuous unrealized loss position, 12 months or greater, fair value	0	0
Continuous unrealized loss position, 12 months or greater, gross unrealized loss	0	0
Continuous unrealized loss position, fair value	82,317	20,752
Continuous unrealized loss position, gross unrealized losses	(31)	(9)
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Continuous unrealized loss position, less than 12 months, fair value	273,570	242,012
Continuous unrealized loss position, less than 12 months, gross unrealized losses	(493)	(181)
Continuous unrealized loss position, 12 months or greater, fair value	0	16,264
Continuous unrealized loss position, 12 months or greater, gross unrealized loss	0	(15)
Continuous unrealized loss position, fair value	273,570	258,276
Continuous unrealized loss position, gross unrealized losses	(493)	(196)
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Continuous unrealized loss position, less than 12 months, fair value	72,843	17,806
Continuous unrealized loss position, less than 12 months, gross unrealized losses	(5)	(14)
Continuous unrealized loss position, 12 months or greater, fair value	0	0
Continuous unrealized loss position, 12 months or greater, gross unrealized loss	0	0
Continuous unrealized loss position, fair value	72,843	17,806
Continuous unrealized loss position, gross unrealized losses	$ (5)	$ (14)

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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 more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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