Income Taxes - Loss Before Provision For (Benefit From) Income Taxes (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Income Tax Disclosure [Abstract] | |||
| United States | $ (508,595) | $ (380,473) | $ (247,784) |
| Foreign | (6,121) | (3,935) | (8,212) |
| Loss before (benefit from) provision for income taxes | $ (514,716) | $ (384,408) | $ (255,996) |