Stock-Based Compensation Expense - Awards Earned and Released (Details) - Performance Shares [Member] - shares shares in Thousands  | 
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2018  | 
Mar. 31, 2017  | 
Mar. 31, 2016  | 
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Number of Shares Earned | 0 | 0 | 31,658 | 
| Number of Shares Withheld for Tax Obligation | 0 | 0 | 8,669 | 
| Number of Shares Released | 0 | 0 | 22,989 | 
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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period. 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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- Definition The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Net number of share options (or share units) granted during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Details 
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