| Fair Value Measurements - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended | 6 Months Ended | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Jun. 30, 2018 | Mar. 31, 2018 | Jun. 30, 2017 | Mar. 31, 2017 | Sep. 28, 2016 | |
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||||||||
| Change in fair value of convertible note embedded derivative liability | $ 952 | $ (3,344) | $ 2,572 | $ (4,652) | |||||
| Stock price (in dollars per share) | $ 1.24 | $ 1.51 | $ 1.24 | $ 1.51 | $ 1.51 | $ 2.01 | $ 1.03 | $ 0.94 | |
| Change in fair value of warrant liability | $ 926 | $ (1,164) | $ 2,496 | $ (1,628) | |||||
| Convertible notes | |||||||||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||||||||
| Original discount | $ 4,916 | ||||||||
| Convertible note embedded derivative liability | |||||||||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||||||||
| Stock price (in dollars per share) | $ 1.24 | $ 1.24 | |||||||
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- Definition Amount, after accumulated amortization, of debt discount. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of expense (income) related to adjustment to fair value of warrant liability. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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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 Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Price of a single share of a number of saleable stocks of a company. No definition available. 
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