1. THE COMPANY AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recent accounting pronouncements (Details) - USD ($)	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Jun. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 59,545,000	$ 64,655,000
Provision for (benefit from) income taxes	453,000	66,000	$ (641,000)
Net operating loss carryforwards	104,000	2,264,000
Valuation allowance	5,913,000	$ 8,939,000
ASU 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid tax asset				$ (595,000)
Retained earnings				(595,000)
Provision for (benefit from) income taxes	$ (43,000)
ASU 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net operating loss carryforwards				654,000
Valuation allowance				$ 654,000