Debt - Interest Expense (Details) - USD ($) $ in Thousands  | 
3 Months Ended | |
|---|---|---|
Jun. 30, 2018  | 
Jun. 30, 2017  | 
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| Debt Instrument [Line Items] | ||
| Interest expense, net | $ 319 | $ 707 | 
| Amortization of debt discount and debt issuance costs | 161 | 353 | 
| Convertible notes | ||
| Debt Instrument [Line Items] | ||
| Interest expense, net | 158 | 354 | 
| Amortization of debt discount and debt issuance costs | $ 161 | $ 353 | 
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- Definition Amount of amortization expense attributable to debt discount (premium) and debt issuance costs. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef 
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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 Amount of the cost of borrowed funds accounted for as interest expense for debt. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Details 
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