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Income Taxes (Details) | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Dec. 31, 2018 USD ($) | Jun. 30, 2018 USD ($) reporting_unit | Dec. 31, 2017 USD ($) | Dec. 31, 2018 USD ($) reporting_unit | Dec. 31, 2017 USD ($) | Mar. 31, 2018 USD ($)
Segment Reporting Information [Line Items] |  |  |  |  |  |
Income tax expense rates (percent) | 18.90% |  | (37.70%) | 19.70% | (3.50%) |
Income tax expense related to continuing operations | $ 123,000,000 |  | $ (263,000,000) | $ 245,000,000 | $ (46,000,000) |
Discrete tax benefit recognized | 31,000,000 |  | 424,000,000 | 138,000,000 | 420,000,000 |
Tax benefits related to change in tax method of inventory rebates | 58,000,000 |  |  |  |  |
Tax expense (benefit) related to impact of the 2017 Tax Act | 27,000,000 |  | (370,000,000) |  |  |
Discrete tax benefit related to conclusion of certain tax audits |  |  | 54,000,000 |  |  |
Pretax goodwill impairment charges | 21,000,000 |  | $ 0 | 591,000,000 | $ 350,000,000 |
Unrecognized tax benefits | 1,010,000,000 |  |  | 1,010,000,000 |  |
Unrecognized tax benefits that would reduce income tax expense and the effective tax rate | 843,000,000 |  |  | 843,000,000 |  |
Increase (decrease) in unrecognized tax benefit | (17,000,000) |  |  | 6,000,000 |  |
Provisional tax benefit due to re-measurement of deferred taxes |  |  |  |  |  | $ 1,324,000,000
Provisional tax expense for the one-time tax |  |  |  |  |  | $ 457,000,000
Discrete tax expense (benefit) related to accumulated earnings and profits | $ 10,000,000 |  |  | (5,000,000) |  |
European Pharmaceutical Solutions and Rexall businesses |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Goodwill impairment, tax benefit |  |  |  | 0 |  |
Pretax goodwill impairment charges |  |  |  | 591,000,000 |  |
European Pharmaceutical Solutions |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Pretax goodwill impairment charges |  | $ 570,000,000 |  | $ 570,000,000 |  |
Number of reporting units | reporting_unit |  | 2 |  | 2 |  |

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- Definition Amount of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operations, attributable to increase (decrease) from transition tax on accumulated earnings of controlled foreign corporation deemed repatriated pursuant to Tax Cuts and Jobs Act. + References No definition available. + Details
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