Income Taxes - Schedule of Changes to Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Income Tax Disclosure [Abstract] | |||
| Unrecognized tax benefits, beginning balance | $ 253 | $ 199 | $ 204 |
| Decreases in balances related to prior year tax positions | (39) | (6) | (31) |
| Increases in balances related to current year tax positions | 59 | 60 | 84 |
| Changes in balances related to effect of U.S. tax law change | (58) | ||
| Unrecognized tax benefits, ending balance | $ 273 | $ 253 | $ 199 |