Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Aug. 31, 2015	Aug. 31, 2014
Pension and Other Postretirement Benefit Liability Adjustments, Tax	$ 2,014	$ 1,455
Unrealized gain (loss) on securities, Tax	(3,228)	114
Unrealized gain (loss) on derivatives, Tax Benefit	$ 0	$ (42)