Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2014
Income tax expense for continuing operations consists of the following components:
Federal	$ 284,046	$ 203,202	$ 139,102
State and local	25,926	25,346	18,286
Current income tax expense	309,972	228,548	157,388
Deferred	(48,791)	14,255	41,967
Income taxes	$ 261,181	$ 242,803	$ 199,355