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Income Taxes Income Taxes - Effective Tax Rates Differing From Prevailing Federal Corporate Income Tax Rates (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2019 | Sep. 30, 2019 | Jun. 30, 2019 | Mar. 31, 2019 | Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Reconciliation of Effective Tax Rates [Line Items] |  |  |  |  |  |  |  |  |  |  |
Tax on income from continuing operations at statutory rate |  |  |  |  |  |  |  |  | $ (38) | $ 57 | $ (99)
Tax on income from continuing operations at statutory rate,tax rate |  |  |  |  |  |  |  |  | 21.00% | 21.00% | 35.00%
Tax-exempt interest |  |  |  |  |  |  |  |  | $ (3) | $ (7) | $ (6)
Tax-exempt interest, tax rate |  |  |  |  |  |  |  |  | 1.80% | (2.50%) | 2.10%
Derivative, Gain (Loss) on Derivative, Net | $ 12 | $ (10) | $ (35) | $ (16) | $ (45) | $ 18 | $ 9 | $ 25 | $ (50) | $ 7 | $ 76
Valuation allowance |  |  |  |  |  |  |  |  | $ 8 | $ 5 | $ 128
Valuation allowance, tax rate |  |  |  |  |  |  |  |  | (4.40%) | 1.90% | (44.90%)
Foreign taxes |  |  |  |  |  |  |  |  | $ 40 | $ 10 | $ (18)
Foreign taxes, tax rate |  |  |  |  |  |  |  |  | (22.10%) | 3.90% | 6.20%
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount |  |  |  |  |  |  |  |  | $ 28 | $ (60) | $ 36
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Percent |  |  |  |  |  |  |  |  | (15.30%) | (22.00%) | (12.70%)
Other, net |  |  |  |  |  |  |  |  | $ (2) | $ 1 | $ 2
Other, net, tax rate |  |  |  |  |  |  |  |  | 1.30% | 0.40% | (0.70%)
Income tax expense (benefit) |  |  |  |  |  |  |  |  | $ 32 | $ 5 | $ 44
Effective Income Tax Rate Reconciliation, Percent |  |  |  |  |  |  |  |  | (17.70%) | 2.00% | (15.70%)
Income Tax Reconciliation Tax Bankruptcy Adjustments |  |  |  |  |  |  |  |  | $ 0 | $ (2) | $ 2
Effective income Tax Reconciliation Tax Bankruptcy Adjustments |  |  |  |  |  |  |  |  | 0.00% | (0.70%) | (0.70%)
Variable Interest Entity, Primary Beneficiary [Member] | Income Loss On Variable Interest Entities [Member] |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Effective Tax Rates [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net |  |  |  |  |  |  |  |  | $ (32) | $ 505 | $ (152)
Variable Interest Entity, Primary Beneficiary [Member] | Currency Swaps [Member] | Income Loss On Variable Interest Entities [Member] |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Effective Tax Rates [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net |  |  |  |  |  |  |  |  | (12) | 11 | (26)
Variable Interest Entity, Primary Beneficiary [Member] | Interest Rate Swaps [Member] | Income Loss On Variable Interest Entities [Member] |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Effective Tax Rates [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net |  |  |  |  |  |  |  |  | $ (20) | $ 493 | $ (127)

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