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
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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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