Taxes (Details) - Schedule of effective income tax rate reconciliation - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Computed federal statutory provision	29.20%	35.00%	35.00%
State income tax provision, net of federal income tax benefit	37.10%	3.30%	3.70%
Difference in effective tax rates on earnings of foreign subsidiaries	(1.30%)	0.00%	1.20%
Charitable contributions	28.60%	(0.30%)	(0.40%)
Tax credits	42.80%	(0.50%)	(0.30%)
Valuation allowances	68.10%	0.10%	(0.70%)
Uncertain Positions	110.30%	2.90%	3.90%
Remeasurement of deferred tax balances	(371.30%)	0.00%	0.00%
Permanent Differences	(177.60%)	(0.30%)	(6.00%)
Other - net	0.80%	0.10%	(0.40%)
Effective tax rates	(233.30%)	40.30%	36.00%
Total provision for income taxes	$ 3.5	$ 35.4	$ 24.7