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Financial Instruments and Fair Value Measurements - Financial Assets Measured At Fair Value On a Recurring Basis (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Level 2 |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | $ 5,246,456 | $ 1,262,987
Certificates of deposit | Level 2 |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 238,819 | 82,101
U.S. treasury securities | Level 2 |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 491,618 | 118,149
Debt securities of U.S. government agencies and corporate entities | Level 2 |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 1,892,169 | 836,863
Fair value recurring |  |
Debt Securities, Available-for-sale [Line Items] |  |
Derivative instruments | 293 |
Assets, Fair Value Disclosure | 3,243,846 | 1,037,113
Fair value recurring | Level 1 |  |
Debt Securities, Available-for-sale [Line Items] |  |
Derivative instruments | 0 |
Assets, Fair Value Disclosure | 620,947 | 0
Fair value recurring | Level 2 |  |
Debt Securities, Available-for-sale [Line Items] |  |
Derivative instruments | 293 |
Assets, Fair Value Disclosure | 2,622,899 | 1,037,113
Fair value recurring | Money market funds |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 620,947 |
Fair value recurring | Money market funds | Level 1 |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 620,947 |
Fair value recurring | Money market funds | Level 2 |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 0 |
Fair value recurring | Certificates of deposit |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 238,819 | 82,101
Fair value recurring | Certificates of deposit | Level 1 |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 0 | 0
Fair value recurring | Certificates of deposit | Level 2 |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 238,819 | 82,101
Fair value recurring | U.S. treasury securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 491,618 | 118,149
Fair value recurring | U.S. treasury securities | Level 1 |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 0 | 0
Fair value recurring | U.S. treasury securities | Level 2 |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 491,618 | 118,149
Fair value recurring | Debt securities of U.S. government agencies and corporate entities |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 1,892,169 | 836,863
Fair value recurring | Debt securities of U.S. government agencies and corporate entities | Level 1 |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | 0 | 0
Fair value recurring | Debt securities of U.S. government agencies and corporate entities | Level 2 |  |
Debt Securities, Available-for-sale [Line Items] |  |
AFS | $ 1,892,169 | $ 836,863

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