Investments and Fair Value Measurement - Unrealized Gain (Loss) on Non-Marketable Securities (Details) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2020 |
Mar. 31, 2019 |
|
| Fair Value Disclosures [Abstract] | ||
| Upward adjustments | $ 0 | $ 0 |
| Downward adjustments (including impairment) | (1,690) | 0 |
| Total unrealized gain for non-marketable equity securities | $ (1,690) | $ 0 |