Note 18 - Valuation Assumptions for Stock Options (Details)		12 Months Ended
		May 31, 2016	May 31, 2015	May 31, 2014
Risk-free interest rate (1)	[1]	1.05%	0.50%	0.42%
Expected volatility (2)	[2]	30.00%	35.00%	45.00%
Expected life (years) (3)	[3]	3 years	2 years	3 years 182 days
Expected dividend yield (4)	[4]

[1] Based on the U.S. Constant Maturity Treasury (CMT) curve in effect at the time of award.

[2] Expected stock price volatility is based on the average historical volatility of the Company when it was publicly traded and weekly stock returns of comparable companies during the period corresponding to the expected life of the options and stock appreciation rights.

[3] Represents the period of time options are expected to remain outstanding.

[4] Except for a $6.0 million dividend related to the Sentilus LLC spin-off, and a $0.4 million dividend related to a stock redemption and tax payments to be made by Holdings issued in fiscal year 2016, the Company has not paid dividends on its common stock.