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	605,473
Issuance of common stock under employee stock option plans, amount	$ 1	2,508			2,509
Repurchase of common stock, shares	(20,636)
Repurchase of common stock, amount		(102)			(102)
Stock-based compensation expense		1,686			1,686
Comprehensive loss:
Net income (loss)				265	265
Net unrealized gain on available-for-sale investments			34		34
Ending Balance, Shares at Dec. 31, 2018	21,992,084
Ending Balance, Amount at Dec. 31, 2018	$ 22	31,483	(108)	59,810	91,207
Beginning Balance - Shares at Sep. 30, 2018	21,947,624
Beginning Balance - Amount at Sep. 30, 2018	$ 22	30,677	(126)	57,548	88,121
Issuance of common stock under employee stock option plans, shares	65,096
Issuance of common stock under employee stock option plans, amount		317			317
Repurchase of common stock, shares	(20,636)
Repurchase of common stock, amount		(102)			(102)
Stock-based compensation expense		591			591
Comprehensive loss:
Net income (loss)				2,262	2,262
Net unrealized gain on available-for-sale investments			18		18
Ending Balance, Shares at Dec. 31, 2018	21,992,084
Ending Balance, Amount at Dec. 31, 2018	$ 22	31,483	(108)	59,810	91,207
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	812,842
Issuance of common stock under employee stock option plans, amount	$ 1	3,628			3,629
Stock-based compensation expense		1,922			1,922
Comprehensive loss:
Net income (loss)				(6,513)	(6,513)
Net unrealized gain on available-for-sale investments			54		54
Ending Balance, Shares at Dec. 31, 2019	23,132,998
Ending Balance, Amount at Dec. 31, 2019	$ 23	39,012	17	53,195	92,247
Beginning Balance - Shares at Sep. 30, 2019	23,052,473
Beginning Balance - Amount at Sep. 30, 2019	$ 23	37,903	28	57,815	95,769
Issuance of common stock under employee stock option plans, shares	80,525
Issuance of common stock under employee stock option plans, amount		480			480
Stock-based compensation expense		629			629
Comprehensive loss:
Net income (loss)				(4,620)	(4,620)
Net unrealized gain on available-for-sale investments			(11)		(11)
Ending Balance, Shares at Dec. 31, 2019	23,132,998
Ending Balance, Amount at Dec. 31, 2019	$ 23	$ 39,012	$ 17	$ 53,195	$ 92,247