Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail)					1 Months Ended	12 Months Ended
	Sep. 02, 2020 $ / shares	Aug. 18, 2020	Nov. 07, 2019 USD ($)	Jun. 25, 2019 $ / shares	Jul. 31, 2017 USD ($)	Mar. 31, 2021 USD ($) shares	Mar. 31, 2020 USD ($) shares
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Reverse stock split						20:1 to 40:1
Conversion ratio		20
Cash and cash equivalents						$ 37,364,000	$ 27,356,000
Restricted cash						111,000	0
Accumulated deficit						(296,291,000)	(279,465,000)
Cash flow from operations						$ 13,323,000	$ 14,882,000
Issuance of common stock | shares						8,670,492	6,527,905
Proceeds from sale of common stock shares						$ 23,798,000	$ 4,996,000
Restricted cash						$ 100,000	0
Estimated useful life of the fixed assets						The estimated useful lives of the fixed assets range between one and seven years.
Impairment of long-lived assets						$ 0	0
Revenue recognized						0	525,000
Sale of inventory and associated assets						12,000	747,000
Revenue recognized under grants						0	2,196,000
Cost of revenue						0	300,000
Dilutive effect						$ 0	$ 0
Common stock equivalents excluded from computing diluted net loss per share | shares						1,000,000	600,000
NIH Research Grants Two [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Revenue recognized under grants					$ 1,657,000
Other Income [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Sale of inventory and associated assets			$ 1,500,000
Product [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Product return revenue						$ 0
Grants [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Revenue recognized under grants						0	$ 52,000
Revenue unutilized remaining available balance						500,000
Grants [Member] | NIH Research Grants Two [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Revenue recognized under grants						0	52,000
Expiration Agreement [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Revenue related to expiration of an agreement							490,000
Research and Development Services [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Deferred revenue						0	$ 0
Directors and Officers [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Severance Costs						2,800,000
New policy premium						$ 800,000
At-The-Market Facility [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Issuance of common stock | shares						1,932,972
Proceeds from sale of common stock shares						$ 23,800,000
Minimum [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Minimum closing bid price | $ / shares	$ 1.00			$ 1
Conversion ratio						20
Useful life of fixed assets, range						1 year
Minimum [Member] | Directors and Officers [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Net of returned insurance premium						$ 1,700,000
Maximum [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Reimbursement of merger-related expenses						$ 300,000
Conversion ratio						40
Maturity of highly liquid investment						90 days
Useful life of fixed assets, range						7 years
Maximum [Member] | Directors and Officers [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Net of returned insurance premium						$ 2,000,000