Fair Value Disclosure - Schedule of Financial Assets Measured at Fair Value (Details) - USD ($) $ in Thousands |
Dec. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Assets: | ||
| Restricted cash | $ 1,854 | |
| Fair Value | $ 42,146 | |
| Total assets measured and recorded at fair value | 517,333 | 197,710 |
| Level 1 | ||
| Assets: | ||
| Restricted cash | 1,854 | |
| Total assets measured and recorded at fair value | 517,333 | 155,564 |
| Level 2 | ||
| Assets: | ||
| Total assets measured and recorded at fair value | 42,146 | |
| Cash | ||
| Assets: | ||
| Cash and cash equivalents | 463,820 | 147,221 |
| Cash | Level 1 | ||
| Assets: | ||
| Cash and cash equivalents | 463,820 | 147,221 |
| Money Market Fund | ||
| Assets: | ||
| Cash and cash equivalents | 51,659 | 8,343 |
| Money Market Fund | Level 1 | ||
| Assets: | ||
| Cash and cash equivalents | $ 51,659 | 8,343 |
| Corporate Bonds and Commercial Paper | ||
| Assets: | ||
| Fair Value | 37,151 | |
| Corporate Bonds and Commercial Paper | Level 2 | ||
| Assets: | ||
| Fair Value | 37,151 | |
| U.S. Government Securities | ||
| Assets: | ||
| Fair Value | 4,995 | |
| U.S. Government Securities | Level 2 | ||
| Assets: | ||
| Fair Value | $ 4,995 |