Income Taxes - Summary of Income Tax Contingencies (Details) - USD ($) $ in Millions |
12 Months Ended | |
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Dec. 31, 2020 |
Dec. 31, 2019 |
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| Changes in uncertain income tax positions | ||
| Balance, beginning of year | $ 406 | $ 387 |
| Increases in tax positions for prior years | 14 | 0 |
| Increases in tax positions for current year | 20 | 31 |
| Decreases in tax positions for prior years | (7) | (12) |
| Balance, end of year | $ 433 | $ 406 |
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. No definition available.
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- Definition Amount of unrecognized tax benefits. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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