Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
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Mar. 31, 2018 |
Mar. 31, 2017 |
Mar. 31, 2016 |
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| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | |||
| Total stock-based compensation expense | $ 16.7 | $ 14.7 | $ 15.1 |
| Liability Awards Expense [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | |||
| Total stock-based compensation expense | 5.6 | 5.4 | 4.8 |
| Equity Awards Expense [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | |||
| Total stock-based compensation expense | $ 11.1 | $ 9.3 | $ 10.3 |
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- Definition Costs and payments related to employee benefits and equity-based compensation, such as pension expense and contributions, other postretirement benefits expense and payments, stock or unit options expense, and amortization of restricted stock or unit. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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