| **Income Taxes - Narrative (Details) - USD ($) $ in Millions**                                      | 3 Months Ended | 9 Months Ended |
|-----------------------------------------------------------------------------------------------------|----------------|----------------|
||
| **Operating Loss Carryforwards [Line Items]**                                                       |           |           |   |   |   |
| Income Taxes Percent Likelihood Of Being Realized Upon Settlement                                   | 50.00%         |           |   | 50.00% |   |
| Income Tax Expense (Benefit)                                                                        | $ 14           |           | $ 12 | $ 25 | $ 37 |
| Unrecognized Tax Benefits                                                                           | 42             |           |   | 42 |   |
| Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense                                | 1              |           |   | $ 1 |   |
| Other Comprehensive Income (Loss) [Member]                                                          |           |           |   |   |   |
| **Operating Loss Carryforwards [Line Items]**                                                       |           |           |   |   |   |
| Income Tax Expense (Benefit)                                                                        | $ (12)         |           |   |   |   |
| Alternative Minimum Tax [Member]                                                                    |           |           |   |   |   |
| **Operating Loss Carryforwards [Line Items]**                                                       |           |           |   |   |   |
| Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount |           | $ 13           |   |   |   |

| X                                                                                                                                                                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Income Taxes Percent Likelihood Of Being Realized Upon Settlement
+ References
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.
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| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
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| - Definition
Amount of unrecognized tax benefits.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of expense for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.
+ References
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