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v3.19.1

Investments (Tables) | 12 Months Ended
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Mar. 31, 2019
Investments [Abstract] |
Summary of Available-for-Sale Securities | The following is a summary of available-for-sale debt securities at March 31, 2018 (in millions):
| Available-for-sale Debt Securities
| Adjusted Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Estimated Fair Value
Available-for-sale debt securities: |  |  |  |  |  |  |
Government agency bonds | $ | 723.2 |  |  | $ | — |  |  | $ | — |  |  | $ | 723.2 |
Municipal bonds - taxable | 14.9 |  |  | — |  |  | — |  |  | 14.9 |
Time deposits | 11.5 |  |  | — |  |  | — |  |  | 11.5 |
Corporate bonds and debt | 542.9 |  |  | — |  |  | — |  |  | 542.9 |
Total | $ | 1,292.5 |  |  | $ | — |  |  | $ | — |  |  | $ | 1,292.5 |
Summary of Amortized Cost and Estimated Fair Value of Available-for-Sale Securities, by Maturity | The amortized cost and estimated fair value of the available-for-sale debt securities at March 31, 2018, by maturity are shown below (in millions). Expected maturities can differ from contractual maturities because the issuers of the securities may have the right to prepay obligations without prepayment penalties, and the Company views its available-for-sale debt securities as available for current operations.
| Adjusted Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Estimated Fair Value
Available-for-sale |  |  |  |  |  |  |
Due in one year or less | $ | 246.5 |  |  | $ | — |  |  | $ | — |  |  | $ | 246.5 |
Due after one year and through five years | 1,046.0 |  |  | — |  |  | — |  |  | 1,046.0 |
Due after five years and through ten years | — |  |  | — |  |  | — |  |  | — |
Due after ten years | — |  |  | — |  |  | — |  |  | — |
Total | $ | 1,292.5 |  |  | $ | — |  |  | $ | — |  |  | $ | 1,292.5 |

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- Definition Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -URI http://asc.fasb.org/topic&trid=2196928 + Details
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- Definition Tabular disclosure of maturities of an entity's investments as well as any other information pertinent to the investments. + References No definition available. + Details
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