CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Total
Beginning Balance - Shares at Mar. 31, 2019	22,320,156
Beginning Balance - Amount at Mar. 31, 2019	$ 22	$ 33,462	$ (37)	$ 59,708	$ 93,155
Issuance of common stock under employee stock option plans, shares	578,032
Issuance of common stock under employee stock option plans, amount	$ 1	2,349			2,350
Stock-based compensation expense		651			651
Comprehensive loss:
Net loss				(125)	(125)
Net unrealized gain (loss) on available-for-sale investments			51		51
Ending Balance, Shares at Jun. 30, 2019	22,898,188
Ending Balance, Amount at Jun. 30, 2019	$ 23	36,462	14	59,583	96,082
Beginning Balance - Shares at Mar. 31, 2020	23,229,286
Beginning Balance - Amount at Mar. 31, 2020	$ 23	40,176	71	49,371	89,641
Issuance of common stock under employee stock option plans, shares	378,487
Issuance of common stock under employee stock option plans, amount	$ 1	2,338			2,339
Stock-based compensation expense		755			755
Comprehensive loss:
Net loss				(6,076)	(6,076)
Net unrealized gain (loss) on available-for-sale investments			25		25
Ending Balance, Shares at Jun. 30, 2020	23,607,773
Ending Balance, Amount at Jun. 30, 2020	$ 24	$ 43,269	$ 96	$ 43,295	$ 86,684