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Income Taxes - Income from continuing operations before income tax (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Income before income taxes: |  |  |
Income before income taxes | $ 1,246 | $ 685 | $ 1,401
Current: |  |  |
Total current tax expense | 371 | 268 | 248
Deferred tax expense (benefit): |  |  |
Total deferred tax benefit | (225) | (18) | (100)
Total income tax expense | 146 | 250 | 148
U.K. |  |  |
Income before income taxes: |  |  |
Income before income taxes | (240) | (420) | (201)
Current: |  |  |
Total current tax expense | 21 | 1 | (54)
Deferred tax expense (benefit): |  |  |
Total deferred tax benefit | 19 | (5) | 59
U.S. federal |  |  |
Income before income taxes: |  |  |
Income before income taxes | (601) | (765) | (329)
Current: |  |  |
Total current tax expense | 101 | 48 | 88
Deferred tax expense (benefit): |  |  |
Total deferred tax benefit | (165) | 12 | (110)
U.S. state and local |  |  |
Current: |  |  |
Total current tax expense | 35 | 18 | 7
Deferred tax expense (benefit): |  |  |
Total deferred tax benefit | (56) | (35) | (9)
Other |  |  |
Income before income taxes: |  |  |
Income before income taxes | 2,087 | 1,870 | 1,931
Current: |  |  |
Total current tax expense | 214 | 201 | 207
Deferred tax expense (benefit): |  |  |
Total deferred tax benefit | $ (23) | $ 10 | $ (40)

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