Taxes - Tax Rate Reconciliation Narrative (Details) - USD ($) $ in Millions |
3 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
Mar. 31, 2020 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Effective income tax rate reconciliation, additional disclosures | ||||
| U.S. corporate tax rate | 21.00% | 21.00% | 21.00% | |
| Measurement period adjustments recognized related to U.S. tax reform | $ 0 | $ 100 | $ 2,000 | |
| Effective tax rate (as a percent) | (18.60%) | 7.20% | 23.00% | |
| Intangible assets | $ 3,400 | $ 3,540 | $ 592 | |
| Increase (decrease) in tax provision from intra-entity sale of intellectual property and impact of U.S. tax reform | $ (900) | |||
| Tax benefit due to change in foreign tax law | $ 200 | |||