Income Taxes - Schedule of Reconciliation of Total Income Tax Expense and Amount Computed by Statutory Federal Income Tax Rate to Income Before Taxes (Details) - USD ($) $ in Millions		12 Months Ended
		May 31, 2020	May 31, 2019	May 31, 2018
Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Abstract]
Taxes computed at federal statutory rate		$ 350	$ 138	$ 1,271
Valuation allowance		(129)	(79)	31
Goodwill impairment charge		75		109
Benefit from U.S. tax loss carryback to prior years		(71)
Non-deductible expenses		70	79	81
State and local income taxes, net of federal benefit		53	44	119
U.S. deferred tax adjustments related to foreign operations		51
Foreign operations		38	(1)	25
Uncertain tax positions		(14)	8	86
Foreign tax rate enactments		(10)	50	6
Benefits from share-based payments		(5)	(18)	(60)
TCJA	[1]		(71)	(1,354)
Foreign tax credits from distributions			(8)	(225)
Corporate structuring transactions	[2]			(255)
Other, net		(25)	(27)	(53)
Provision for Income Taxes, Total		$ 383	$ 115	$ (219)
Effective Tax Rate		23.00%	17.60%	(5.00%)

[1] Primary components in 2018 were a $1.15 billion benefit from the remeasurement of our net U.S. deferred tax liability and a $204 million one-time benefit from a contribution to our U.S. Pension Plans in 2018.

[2] The 2018 net benefit consists of foreign deferred tax benefits of $434 million, which were partially offset by U.S. deferred tax expenses of $179 million.