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Principles of Consolidation And Other Matters (Details) - USD ($) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2021 | Mar. 31, 2020 | Dec. 31, 2020
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] |  |  |
Operating funds related to regulatory requirements or as collateral under captive insurance arrangements | $ 272,000,000 |  | $ 270,000,000
Equity method investments lag period | 3 months |  |
Gain (loss) on investment income, net | $ 11,000,000 | $ (2,000,000) |
Effective tax rate (as a percent) | 24.50% | 23.80% |
Excess tax benefit related to share-based payments, percent | 1.10% | 2.60% |
Unrecognized tax benefits | $ 96,000,000 |  | $ 98,000,000
Minimum |  |  |
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] |  |  |
Reasonably possible decrease in unrecognized tax benefits | 0 |  |
Maximum |  |  |
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] |  |  |
Reasonably possible decrease in unrecognized tax benefits | $ 35,000,000 |  |

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