Segment Disclosure (Details) (USD $)	3 Months Ended		9 Months Ended
	Feb. 28, 2013	Feb. 29, 2012	Feb. 28, 2013 item	Feb. 29, 2012	May 31, 2012
Segment Disclosure
Number of operating segments			3
Consolidated financial information by segment
Revenues	$ 133,661,000	$ 104,118,000	$ 384,777,000	$ 309,785,000
Gross profit	34,206,000	29,584,000	109,828,000	92,219,000
Income from operations	4,982,000	5,422,000	28,435,000	25,089,000
Depreciation and amortization	7,192,000	5,765,000	19,693,000	15,989,000
Intangible assets, net	56,428,000		56,428,000		34,469,000
Goodwill	125,532,000		125,532,000		96,819,000
Total assets	396,914,000		396,914,000		329,816,000
Services
Consolidated financial information by segment
Revenues	90,537,000	80,895,000	278,147,000	253,493,000
Revenue from transaction with other operating segments	600,000	500,000	2,800,000	2,300,000
Gross profit	20,496,000	20,640,000	72,128,000	68,001,000
Income from operations	6,293,000	7,186,000	28,597,000	27,927,000
Depreciation and amortization	4,660,000	4,587,000	13,763,000	12,988,000
Intangible assets, net	15,880,000		15,880,000		17,180,000
Goodwill	60,719,000		60,719,000		58,746,000
Total assets	205,988,000		205,988,000		204,209,000
International
Consolidated financial information by segment
Revenues	37,516,000	17,164,000	88,722,000	38,794,000
Revenue from transaction with other operating segments	200,000	300,000	500,000	500,000
Gross profit	9,851,000	4,586,000	24,231,000	12,263,000
Income from operations	586,000	321,000	3,457,000	2,373,000
Depreciation and amortization	1,941,000	670,000	4,400,000	1,474,000
Intangible assets, net	29,853,000		29,853,000		6,390,000
Goodwill	51,616,000		51,616,000		24,481,000
Total assets	150,551,000		150,551,000		82,579,000
Products and Systems
Consolidated financial information by segment
Revenues	7,645,000	9,824,000	25,618,000	26,429,000
Revenue from transaction with other operating segments	1,300,000	3,100,000	4,200,000	6,400,000
Gross profit	3,790,000	4,938,000	13,010,000	12,952,000
Income from operations	1,699,000	2,392,000	6,481,000	5,652,000
Depreciation and amortization	617,000	500,000	1,596,000	1,451,000
Intangible assets, net	9,911,000		9,911,000		10,095,000
Goodwill	13,197,000		13,197,000		13,592,000
Total assets	38,262,000		38,262,000		43,914,000
Corporate and eliminations
Consolidated financial information by segment
Revenues	(2,037,000)	(3,765,000)	(7,710,000)	(8,931,000)
Gross profit	69,000	(580,000)	459,000	(997,000)
Income from operations	(3,596,000)	(4,477,000)	(10,100,000)	(10,863,000)
Depreciation and amortization	(26,000)	8,000	(66,000)	76,000
Intangible assets, net	784,000		784,000		804,000
Total assets	$ 2,113,000		$ 2,113,000		$ (886,000)