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Healthcare Technology Net Asset Exchange (Details) - USD ($) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Mar. 31, 2018
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Net income (loss) from Change Healthcare | $ (56,000,000) | $ (61,000,000) |  |  | $ (112,000,000) | $ (181,000,000) |
Carrying value of investment | 3,609,000,000 |  |  |  | 3,609,000,000 |  | $ 3,728,000,000
Change Healthcare, LLC (“Change Healthcare”) | Tax Receivable Agreement (“TRA”) |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Noncurrent liability | 0 |  |  |  | 0 |  | 90,000,000
Other | Change Healthcare, LLC (“Change Healthcare”) | Tax Receivable Agreement (“TRA”) |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Gain on derecognition of liability, pre-tax | 90,000,000 |  |  |  |  |  |
Gain on derecognition of liability, after tax | 66,000,000 |  |  |  |  |  |
Joint Venture | Transition Services Agreements (“TSA”) |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Fees incurred or earned from TSA and Advisory agreements | $ 26,000,000 | 10,000,000 |  |  | $ 36,000,000 | 47,000,000 |
Joint Venture | Core MTS Businesses |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Expected ownership interest in the joint venture (percent) | 70.00% |  |  |  | 70.00% |  |
Change Healthcare, LLC (“Change Healthcare”) | Core MTS Businesses | Operating Segments | Other |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Gain from sale of business, pre-tax |  |  | $ 37,000,000 | $ 3,947,000,000 |  |  |
Gain from sale of business, after tax |  |  | $ 22,000,000 | $ 3,018,000,000 |  |  |
Proceeds from Divestiture of Businesses |  | 126,000,000 |  |  |  |  |
Change Healthcare, LLC (“Change Healthcare”) | Joint Venture |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Expected ownership interest in the joint venture (percent) |  |  |  | 70.00% |  |  |
Net income (loss) from Change Healthcare | $ (56,000,000) | $ (61,000,000) |  |  | $ (112,000,000) | $ (181,000,000) |
Carrying value of investment | 3,609,000,000 |  |  |  | 3,609,000,000 |  | 3,728,000,000
Excess of carrying value of investment over proportional share of book value | $ 4,269,000,000 |  |  |  | $ 4,269,000,000 |  | $ 4,472,000,000

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