Stockholders' Equity - Additional Information (Detail)			3 Months Ended	12 Months Ended
	May 10, 2017 shares	Apr. 29, 2015 USD ($) $ / shares shares	Mar. 31, 2017 USD ($) $ / shares shares	Mar. 31, 2018 USD ($) plan shares	Mar. 31, 2017 USD ($) $ / shares shares	Mar. 31, 2016 USD ($) shares	Jan. 27, 2017 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock plans | plan				2
Options granted in period (in shares) | shares				0	9,703	0
Weighted-average grant-date fair value of stock options granted (in dollars per share) | $ / shares					$ 4.06
Intrinsic value of exercisable options			$ 0	$ 0	$ 0	$ 0
Granted (in shares) | shares				854,307
Number of shares vested (in shares) | shares				344,147
Stock-based compensation expense (less than $0.1 million)				$ 2,692,000	$ 2,892,000	3,248,000
Common stock, shares issued (in shares) | shares			14,713,839	21,138,689	14,713,839
Proceeds from sale of stock			$ 2,500,000	$ 0	$ 2,527,000	0
Cowen and Company, LLC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares issued (in shares) | shares		4,000,000.0
Sale of stock, price per share (in dollars per share) | $ / shares		$ 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				$ 200,000
Weighted-average period over which unrecognized compensation expense is expected to be recognized (years)				1 year
Stock-based compensation expense (less than $0.1 million)				$ 227,000	323,000	663,000
Restricted stock and stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of restricted stock granted				3,300,000	1,700,000	2,600,000
Unrecognized compensation cost for unvested employee stock-based compensation awards outstanding, net of forfeitures				$ 2,400,000
Weighted-average period over which unrecognized compensation expense is expected to be recognized (years)				1 year 11 months
Total fair value of restricted stock vested				$ 1,400,000	2,300,000	1,700,000
Stock-based compensation expense (less than $0.1 million)				$ 2,434,000	$ 2,569,000	$ 2,574,000
Performance-based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares) | shares				267,125	0	0
Restricted stock units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares vested (in shares) | shares				20,000
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) | shares				259,856
Percentage of purchase discount				15.00%
Stock-based compensation expense (less than $0.1 million)				$ 31,000	$ 0	$ 11,000
Over-allotment option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from additional equity offering				$ 17,000,000
Over-allotment options, expiration period	30 days
Issuance of common stock (in shares) | shares	600,000
ATM arrangement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of stock, price per share (in dollars per share) | $ / shares			$ 6.79		$ 6.79
Sale of stock							$ 10,000,000.0
Proceeds from sale of stock					$ 2,500,000
Number of shares sold (in shares) | 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
Fair value time period				3 days
Number of shares authorized for issuance under the plan (in shares) | shares				113,662
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) | shares				666,092
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