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, 2018	21,407,247
Beginning Balance - Amount at Mar. 31, 2018	$ 21	$ 27,391	$ (142)	$ 59,545	$ 86,815
Issuance of common stock under employee stock option plans, shares	540,377
Issuance of common stock under employee stock option plans, amount	$ 1	2,192			2,193
Stock-based compensation expense		1,094			1,094
Comprehensive loss:
Net loss				(1,997)	(1,997)
Net unrealized gain on available-for-sale investments			16		16
Ending Balance, Shares at Sep. 30, 2018	21,947,624
Ending Balance, Amount at Sep. 30, 2018	$ 22	30,677	(126)	57,548	88,121
Beginning Balance - Shares at Jun. 30, 2018	21,760,094
Beginning Balance - Amount at Jun. 30, 2018	$ 21	29,435	(152)	57,899	87,203
Issuance of common stock under employee stock option plans, shares	187,530
Issuance of common stock under employee stock option plans, amount	$ 1	690			691
Stock-based compensation expense		552			552
Comprehensive loss:
Net loss				(351)	(351)
Net unrealized gain on available-for-sale investments			26		26
Ending Balance, Shares at Sep. 30, 2018	21,947,624
Ending Balance, Amount at Sep. 30, 2018	$ 22	30,677	(126)	57,548	88,121
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	732,317
Issuance of common stock under employee stock option plans, amount	$ 1	3,148			3,149
Stock-based compensation expense		1,293			1,293
Comprehensive loss:
Net loss				(1,893)	(1,893)
Net unrealized gain on available-for-sale investments			65		65
Ending Balance, Shares at Sep. 30, 2019	23,052,473
Ending Balance, Amount at Sep. 30, 2019	$ 23	37,903	28	57,815	95,769
Beginning Balance - Shares at Jun. 30, 2019	22,898,188
Beginning Balance - Amount at Jun. 30, 2019	$ 23	36,462	14	59,583	96,082
Issuance of common stock under employee stock option plans, shares	154,285
Issuance of common stock under employee stock option plans, amount		799			799
Stock-based compensation expense		642			642
Comprehensive loss:
Net loss				(1,768)	(1,768)
Net unrealized gain on available-for-sale investments			14		14
Ending Balance, Shares at Sep. 30, 2019	23,052,473
Ending Balance, Amount at Sep. 30, 2019	$ 23	$ 37,903	$ 28	$ 57,815	$ 95,769