Summary of Significant Accounting Policies (Advertising Expense) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
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| Accounting Changes and Error Corrections [Abstract] | |||
| Advertising Expense | $ 57 | $ 115 | $ 92 |
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- References No definition available.
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- Definition Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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