BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Allowance For Doubtful Accounts (Details) - 10K - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Allowance for Doubtful Accounts Receivable [Roll Forward]
Provision	$ 499	$ 651	$ 967
Allowance for Doubtful Accounts [Member]
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	946	1,156	1,044
Provision	499	651	967
Write-off	(895)	(861)	(855)
Balance at close of year	$ 550	$ 946	$ 1,156