Consolidated Condensed Statements of Income (Loss) (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Aug. 31, 2017	Aug. 31, 2016
Income Statement [Abstract]
Net sales	$ 85,411	$ 88,098
Cost of sales (exclusive of intangible amortization)	44,182	43,066
Gross profit	41,229	45,032
Operating expenses
Research and development	6,441	6,709
Sales and marketing	19,402	19,455
General and administrative	8,056	8,201
Amortization of intangibles	4,096	4,235
Change in fair value of contingent consideration	105	443
Acquisition, restructuring and other items, net	2,989	2,417
Total operating expenses	41,089	41,460
Operating income	140	3,572
Other (expenses) income
Interest expense	(723)	(719)
Other income (expense)	567	50
Total other expenses, net	(156)	(669)
Income (loss) before income tax expense (benefit)	(16)	2,903
Income tax expense	19	1,603
Net income (loss)	$ (35)	$ 1,300
Income (loss) per share
Basic (in usd per share)	$ 0.00	$ 0.04
Diluted (in usd per share)	$ 0.00	$ 0.04
Basic weighted average shares outstanding (in shares)	36,919	36,319
Diluted weighted average shares outstanding (in shares)	36,919	36,698