Income Taxes - Components of Income Before Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2018
Income before income taxes for continuing operations consists of the following components:
U.S. operations	$ 1,035,902	$ 1,061,505	$ 798,215
Foreign operations	22,389	40,894	42,786
Income before income taxes from continuing operations	$ 1,058,291	$ 1,102,399	$ 841,001