BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Allowance For Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2014
Allowance for Doubtful Accounts Receivable [Roll Forward]
Provision	$ 651	$ 967	$ 434
Allowance for Doubtful Accounts [Member]
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	1,156	1,044	1,393
Provision	651	967	434
Write-off	(861)	(855)	(783)
Balance at close of year	$ 946	$ 1,156	$ 1,044