Condensed Consolidated Statements of Income (USD $) In Thousands, except Per Share data	3 Months Ended
	Aug. 31, 2011	Aug. 31, 2010
Sales:
Sales from products	$ 327,898	$ 281,756
Sales from services	151,392	122,637
Total sales	479,290	404,393
Cost and operating expenses:
Cost of products	287,362	237,209
Cost of services	117,088	97,183
Selling, general and administrative	41,730	41,242
Total cost and operating expenses	446,180	375,634
Earnings from joint ventures	205	28
Operating income	33,315	28,787
Gain on extinguishment of debt		97
Interest expense	(7,518)	(7,433)
Interest income	104	160
Income from continuing operations before provision for income taxes	25,901	21,611
Provision for income taxes	8,938	7,564
Income from continuing operations	16,963	14,047
Discontinued operations, net of tax	(314)	(373)
Net income	$ 16,649	$ 13,674
Earnings per share - basic:
Earnings from continuing operations (in dollars per share)	$ 0.42	$ 0.37
Loss from discontinued operations (in dollars per share)	$ (0.01)	$ (0.01)
Earnings per share - basic (in dollars per share)	$ 0.41	$ 0.36
Earnings per share - diluted:
Earnings from continuing operations (in dollars per share)	$ 0.41	$ 0.36
Loss from discontinued operations (in dollars per share)		$ (0.01)
Earnings per share - diluted (in dollars per share)	$ 0.41	$ 0.35