| Assets and Liabilities Measured at Fair Value on Recurring Basis |
The following table presents our fair value hierarchy for our assets measured at fair value on a recurring basis as of December 31, 2019 (in thousands): | | | | | | | | | | | | | | Level 1 | | Level 2 | | Total | Cash equivalents: | | | | | | Money market funds | $ | 486,982 |
| | $ | — |
| | $ | 486,982 |
| Commercial paper | — |
| | 86,388 |
| | 86,388 |
| Marketable securities: | | | | | | Commercial paper | — |
| | 101,490 |
| | 101,490 |
| Corporate notes and bonds | — |
| | 1,661,330 |
| | 1,661,330 |
| Certificates of deposit | — |
| | 38,045 |
| | 38,045 |
| U.S. government and agency securities | — |
| | 127,784 |
| | 127,784 |
| Total | $ | 486,982 |
| | $ | 2,015,037 |
| | $ | 2,502,019 |
|
The following table presents our fair value hierarchy for our assets measured at fair value on a recurring basis as of December 31, 2018 (in thousands): | | | | | | | | | | | | | | Level 1 | | Level 2 | | Total | Cash equivalents: | | | | | | Money market funds | $ | 229,047 |
| | $ | — |
| | $ | 229,047 |
| Commercial paper | — |
| | 16,961 |
| | 16,961 |
| Certificates of deposit | — |
| | 2,465 |
| | 2,465 |
| Marketable securities: | | | | | | Commercial paper | — |
| | 108,061 |
| | 108,061 |
| Corporate notes and bonds | — |
| | 1,229,714 |
| | 1,229,714 |
| Certificates of deposit | — |
| | 73,585 |
| | 73,585 |
| U.S. government and agency securities | — |
| | 102,214 |
| | 102,214 |
| Total | $ | 229,047 |
| | $ | 1,533,000 |
| | $ | 1,762,047 |
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