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Significant Accounting Policies Narrative (Details) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Dec. 31, 2018 | Dec. 31, 2018 segment | Mar. 31, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |
Number of reportable segments | segment |  | 3 |
ASU 2016-16 |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |
Cumulative effect of new accounting pronouncement | $ |  |  | $ 152
Revenue | Product and Services Concentration | Distribution and Retail Business |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |
Revenues derived by business line (percent) | 98.00% | 98.00% |
Revenue | Product and Services Concentration | Services Business |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |
Revenues derived by business line (percent) | 2.00% | 2.00% |

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