CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Retained Earnings	Total
Beginning Balance - Shares at Mar. 31, 2015	23,128,372
Beginning Balance - Amount at Mar. 31, 2015	$ 23	$ 29,407	$ 26	$ 66,940	$ 96,396
Issuance of common stock under employee stock option plans, shares	199,961
Issuance of common stock under employee stock option plans, amount		818			818
Repurchase and retirement of common stock, shares	(1,611,969)
Repurchase and retirement of common stock, amount	$ (1)	(7,025)			(7,026)
Stock-based compensation expense		1,850			1,850
Comprehensive loss:
Net income (loss)				(2,170)	(2,170)
Net unrealized gain (loss) on available-for-sale investments			1		1
Ending Balance, Shares at Mar. 31, 2016	21,716,364
Ending Balance, Amount at Mar. 31, 2016	$ 22	25,050	27	64,770	89,869
Issuance of common stock under employee stock option plans, shares	539,834
Issuance of common stock under employee stock option plans, amount	$ 1	2,013			2,014
Repurchase and retirement of common stock, shares	(1,643,441)
Repurchase and retirement of common stock, amount	$ (2)	(7,110)			(7,112)
Stock-based compensation expense		1,877			1,877
Comprehensive loss:
Net income (loss)				(115)	(115)
Net unrealized gain (loss) on available-for-sale investments			(89)		(89)
Ending Balance, Shares at Mar. 31, 2017	20,612,757
Ending Balance, Amount at Mar. 31, 2017	$ 21	21,830	(62)	64,655	86,444
Issuance of common stock under employee stock option plans, shares	794,490
Issuance of common stock under employee stock option plans, amount		3,491			3,491
Stock-based compensation expense		2,070			2,070
Impact of adoption of ASU 2016-16 | ASU 2016-16				(595)	(595)
Comprehensive loss:
Net income (loss)				(4,515)	(4,515)
Net unrealized gain (loss) on available-for-sale investments			(80)		(80)
Ending Balance, Shares at Mar. 31, 2018	21,407,247
Ending Balance, Amount at Mar. 31, 2018	$ 21	$ 27,391	$ (142)	$ 59,545	$ 86,815