Financial Instruments (Non-Marketable Equity Securities) (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2021 |
Jun. 30, 2020 |
Jun. 30, 2021 |
Jun. 30, 2020 |
|
| Fair Value Disclosures [Abstract] | ||||
| Unrealized gains | $ 1,852 | $ 189 | $ 5,128 | $ 545 |
| Unrealized losses (including impairment) | (65) | (98) | (67) | (1,395) |
| Total unrealized gain (loss) for non-marketable equity securities | $ 1,787 | $ 91 | $ 5,061 | $ (850) |