The following tables summarize the Company’s investments by major security type (in millions): | | | | | | | | | | | | | | | | December 31, 2023 | | Amortized
Cost | Gross
Unrealized
Gains | Gross
Unrealized
Losses | Total
Estimated
Fair Value | | Short-term investments | | | | | | Debt securities: | | | | | | Certificates of deposit | $ | 172 | | $ | — | | $ | — | | $ | 172 | | | Government bonds | 332 | | 1 | | — | | 333 | | | Commercial paper | 366 | | — | | — | | 366 | | | Corporate debt securities | 1,490 | | 4 | | (3) | | 1,491 | | Mortgage-backed and asset-backed securities | 148 | | 1 | | (4) | | 145 | | | Total debt securities | 2,508 | | 6 | | (7) | | 2,507 | | | Time deposits | 690 | | — | | — | | 690 | | | | | | | Total short-term investments | $ | 3,198 | | $ | 6 | | $ | (7) | | $ | 3,197 | | | | | | | Long-term investments (1) | | | | | | Debt securities: | | | | | | Corporate debt securities | $ | 13 | | $ | — | | $ | (9) | | $ | 4 | |
| | | | | | | | | | | | | | | | March 31, 2024 | | Amortized
Cost | Gross
Unrealized
Gains | Gross
Unrealized
Losses | Total
Estimated
Fair Value | | Short-term investments | | | | | | Debt securities: | | | | | Certificates of deposit | $ | 13 | | $ | — | | $ | — | | $ | 13 | | Government bonds | 345 | | — | | — | | 345 | | Commercial paper | 500 | | — | | — | | 500 | | Corporate debt securities | 1,480 | | 3 | | (4) | | 1,479 | | Mortgage-backed and asset-backed securities | 191 | | — | | (4) | | 187 | | | Total debt securities | 2,529 | | 3 | | (8) | | 2,524 | | | Time deposits | 740 | | — | | — | | 740 | | | | | | | Total short-term investments | $ | 3,269 | | $ | 3 | | $ | (8) | | $ | 3,264 | | | | | | | Long-term investments (1) | | | | | | Debt securities: | | | | | | Corporate debt securities | $ | 13 | | $ | — | | $ | (9) | | $ | 4 | |
(1)Classified within other assets, noncurrent on the unaudited condensed consolidated balance sheets.
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