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Schedule of Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands | Sep. 27, 2020 | Dec. 31, 2019
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Schedule of Available-for-sale Securities |  |
Available-for-sale marketable securities, Cost | $ 361,666 | $ 211,596
Available-for-sale marketable securities, Unrealized Gain | 8,284 | 4,687
Available-for-sale marketable securities, Unrealized (Loss) | (87) | (262)
Available-for-sale marketable securities, Fair Market Value | 369,863 | 216,021
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses | 24,431 | 23,999
U.S. Treasury Securities |  |
Schedule of Available-for-sale Securities |  |
Available-for-sale marketable securities, Cost | 201,193 | 42,167
Available-for-sale marketable securities, Unrealized Gain | 1,606 | 431
Available-for-sale marketable securities, Unrealized (Loss) | (33) | (216)
Available-for-sale marketable securities, Fair Market Value | 202,766 | 42,382
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses | 20,611 | 17,556
Commercial Paper |  |
Schedule of Available-for-sale Securities |  |
Available-for-sale marketable securities, Cost | 102,141 | 54,124
Available-for-sale marketable securities, Unrealized Gain | 8 | 26
Available-for-sale marketable securities, Unrealized (Loss) | 0 | (1)
Available-for-sale marketable securities, Fair Market Value | 102,149 | 54,149
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses | 500 | 1,391
Corporate Debt Securities |  |
Schedule of Available-for-sale Securities |  |
Available-for-sale marketable securities, Cost | 44,350 | 93,267
Available-for-sale marketable securities, Unrealized Gain | 6,417 | 4,081
Available-for-sale marketable securities, Unrealized (Loss) | (52) | (41)
Available-for-sale marketable securities, Fair Market Value | 50,715 | 97,307
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses | 2,207 | 2,009
Certificates of Deposit and Time Deposits |  |
Schedule of Available-for-sale Securities |  |
Available-for-sale marketable securities, Cost | 2,414 | 4,751
Available-for-sale marketable securities, Unrealized Gain | 2 |
Available-for-sale marketable securities, Unrealized (Loss) | 0 |
Available-for-sale marketable securities, Fair Market Value | 2,416 | 4,751
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses | 0 |
U.S. Government Agency Securities |  |
Schedule of Available-for-sale Securities |  |
Available-for-sale marketable securities, Cost | 4,288 | 9,942
Available-for-sale marketable securities, Unrealized Gain | 60 | 14
Available-for-sale marketable securities, Unrealized (Loss) | (2) | (4)
Available-for-sale marketable securities, Fair Market Value | 4,346 | 9,952
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses | 1,113 | 3,043
Debt Mutual Funds |  |
Schedule of Available-for-sale Securities |  |
Available-for-sale marketable securities, Cost | 6,661 | 6,753
Available-for-sale marketable securities, Unrealized Gain | 191 | 135
Available-for-sale marketable securities, Fair Market Value | 6,852 | 6,888
Non-U.S. Government Securities |  |
Schedule of Available-for-sale Securities |  |
Available-for-sale marketable securities, Cost | 619 | 592
Available-for-sale marketable securities, Fair Market Value | $ 619 | $ 592

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