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Stockholders' Equity - Additional Information (Detail) - USD ($) |  | 12 Months Ended |
--- | --- | --- | ---
Apr. 29, 2015 | Mar. 31, 2017 | Mar. 31, 2016 | Mar. 31, 2015 | Jan. 27, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Options granted in period (in shares) |  | 9,703 | 0 |  |
Weighted-average grant-date fair value of stock options granted (in dollars per share) |  | $ 4.06 | $ 10.18 |  |
Intrinsic value of exercisable options |  | $ 0 | $ 0 | $ 0 |
Granted (in shares) |  | 171,000 |  |  |
Number of shares cancelled (in shares) |  | 0 |  |  |
Stock-based compensation expense (less than $0.1 million in 2016) |  | $ 2,892,000 | $ 3,248,000 | 5,936,000 |
Common stock, shares issued (in shares) |  | 14,713,839 | 14,107,126 |  |
Proceeds from sale of stock |  | $ 2,527,000 | $ 0 | 5,839,000 |
Cowen and Company, LLC |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Common stock, shares issued (in shares) | 4,000,000 |  |  |  |
Sale of stock, price per share (in dollars per share) | $ 6.00 |  |  |  |
Proceeds from additional equity offering | $ 22,300,000 |  |  |  |
Stock options |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Unrecognized compensation cost for unvested employee stock-based compensation awards outstanding, net of forfeitures |  | $ 400,000 |  |  |
Weighted-average period over which unrecognized compensation expense is expected to be recognized (years) |  | 1 year 10 months 24 days |  |  |
Stock-based compensation expense (less than $0.1 million in 2016) |  | $ 323,000 | 663,000 | 1,851,000 |
Restricted stock and stock awards |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Total fair value of restricted stock granted |  | 1,700,000 | 2,600,000 | 5,600,000 |
Unrecognized compensation cost for unvested employee stock-based compensation awards outstanding, net of forfeitures |  | $ 1,800,000 |  |  |
Weighted-average period over which unrecognized compensation expense is expected to be recognized (years) |  | 1 year 3 months 18 days |  |  |
Total fair value of restricted stock vested |  | $ 2,300,000 | 1,700,000 | 3,100,000 |
Stock-based compensation expense (less than $0.1 million in 2016) |  | $ 2,569,000 | $ 2,574,000 | $ 4,063,000 |
Performance-based restricted stock |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Granted (in shares) |  | 0 | 0 | 38,021 |
Restricted stock units (RSUs) |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Number of shares cancelled (in shares) |  | 3,333 |  |  |
Employee stock purchase plan |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Number of shares authorized for issuance under the plan (in shares) |  | 300,013 |  |  |
Percentage of purchase discount |  | 15.00% |  |  |
Stock-based compensation expense (less than $0.1 million in 2016) |  | $ 0 | $ 11,000 | $ 22,000 |
ATM arrangement |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Sale of stock, price per share (in dollars per share) |  | $ 6.79 |  |  |
Sale of stock |  |  |  |  | $ 10,000,000.0
Number of shares sold (in shares) |  | 379,693 |  |  |
2007 Director stock option plan |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Vesting period, in years |  | 2 years |  |  |
Grant date value of shares granted by option upon election to board |  | $ 40,000 |  |  |
Total fair value of restricted stock granted |  | $ 40,000 |  |  |
Number of shares authorized for issuance under the plan (in shares) |  | 150,802 |  |  |
2007 Plan |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Contractual life of options, in years |  | 10 years |  |  |
Vesting period, in years |  | 3 years |  |  |
Number of shares authorized for issuance under the plan (in shares) |  | 1,405,110 |  |  |
2007 Plan | Minimum |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Vesting period, in years |  | 3 years |  |  |
2007 Plan | Maximum |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Vesting period, in years |  | 5 years |  |  |

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