Schedule II: Valuation and Qualifying Accounts (Details) - Allowance for doubtful accounts and sales credits - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] | |||
| Balance at Beginning of Year | $ 729 | $ 674 | $ 467 |
| Additions | 1,481 | 1,115 | 1,131 |
| Usage | (1,457) | (1,060) | (924) |
| Balance at End of Year | $ 753 | $ 729 | $ 674 |