Note 16 - Condensed Consolidating Financial Information of Guarantor Subsidiaries (Details) - Condensed Consolidating Cash Flow Information (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Feb. 28, 2014	Feb. 28, 2013
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	$ 10,541	$ (4,828)
Net cash provided by ( used in) investing activities	(9,374)	(6,915)
Net cash provided by ( used in) financing activities	(5,008)	12,543
Effect of exchange rate changes on cash and cash equivalents	481	142
Increase (decrease) in cash and cash equivalents	(3,360)	942
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	29,388	18,578
CASH AND CASH EQUIVALENTS AT END OF PERIOD	26,028	19,520
Consolidation, Eliminations [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(903)	88
Net cash provided by ( used in) investing activities	29
Net cash provided by ( used in) financing activities	785
Effect of exchange rate changes on cash and cash equivalents	89	(88)
Parent Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	63	(16,071)
Net cash provided by ( used in) investing activities	3,096	(3,798)
Net cash provided by ( used in) financing activities	(4,975)	12,543
Effect of exchange rate changes on cash and cash equivalents	(501)
Increase (decrease) in cash and cash equivalents	(2,317)	(7,326)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	6,971	8,093
CASH AND CASH EQUIVALENTS AT END OF PERIOD	4,654	767
Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(2,351)	2,464
Net cash provided by ( used in) investing activities	(1,954)	(2,502)
Net cash provided by ( used in) financing activities	(34)
Increase (decrease) in cash and cash equivalents	(4,339)	(38)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	4,107	(144)
CASH AND CASH EQUIVALENTS AT END OF PERIOD	(232)	(182)
Non-Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	13,732	8,691
Net cash provided by ( used in) investing activities	(10,545)	(615)
Net cash provided by ( used in) financing activities	(784)
Effect of exchange rate changes on cash and cash equivalents	893	231
Increase (decrease) in cash and cash equivalents	3,296	8,306
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	18,310	10,629
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 21,606	$ 18,935