Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits	$ 0	$ 0
Increase (decrease) in valuation allowance	1,676,000	2,107,000
Federal net operating loss carryforwards	119,845,000
State net operating loss carryforwards	69,040,000
Foreign net operating loss carryforwards	$ 326,000
Federal and state net operating loss carryforwards expiring year	2028
Federal research tax credit carryforwards expiration period	2028
Accrued expense regarding interest or penalties	$ 0
Federal [Member]
Operating Loss Carryforwards [Line Items]
Research tax credit carryforwards	1,793,000
State [Member]
Operating Loss Carryforwards [Line Items]
Research tax credit carryforwards	$ 2,076,000
Accounting Standards Update 2016-09 [Member]
Operating Loss Carryforwards [Line Items]
Unrecognized excess tax benefits		$ 6,332,000