Financial Instruments (Non-Marketable Equity Securities) (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Fair Value Disclosures [Abstract] | ||
| Unrealized gains | $ 2,163 | $ 4,285 |
| Unrealized losses (including impairment) | (372) | (178) |
| Total unrealized gain (loss) for non-marketable equity securities | $ 1,791 | $ 4,107 |