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Basis of Presentation (Details) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2021 USD ($)
Accounting Standards Update and Change in Accounting Principle [Abstract] |  |
Cumulative effect of new accounting standards | $ 0 |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Cumulative effect of new accounting standards | 0 |
Adjustment Related to Underaccrued Payroll Tax Credits Included in Payroll support and other voluntary Employee programs, net |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Prior Period Reclassification Adjustment | 88 |
Other comprehensive income (loss) other changes net of tax |  |
Accounting Standards Update and Change in Accounting Principle [Abstract] |  |
Cumulative effect of new accounting standards | (31) |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Cumulative effect of new accounting standards | (31) |
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax | (60) | [1]
Accumulated other comprehensive income (loss) |  |
Accounting Standards Update and Change in Accounting Principle [Abstract] |  |
Cumulative effect of new accounting standards | (19) |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Cumulative effect of new accounting standards | $ (19) |
[1] | Investment gains related to prior periods that were reclassified from AOCI into Other (gains) losses, net. See Note 1.

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