General - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended			9 Months Ended
	May 31, 2018	Feb. 28, 2019	Nov. 30, 2018	Feb. 28, 2018	Feb. 28, 2019	Feb. 28, 2018	Jan. 26, 2016
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Gross contract assets related to in-transit packages	$ 542	$ 526			$ 526
Contract assets net of deferred unearned revenue	363	353			353
Contract liabilities related to advance payments from customers	13	9			$ 9
Payment terms of customer contracts					Under the typical payment terms of our customer contracts, the customer pays at periodic intervals (e.g., every 15 days, 30 days, 45 days, etc.) for shipments included on invoices received. It is not customary business practice to extend payment terms past 90 days, and as such, we do not have a practice of including a significant financing component within our revenue contracts with customers.
Stock-based compensation		33		$ 32	$ 141	$ 135
Business realignment costs		$ 4		$ 0	$ 4	$ 0
Diluted		$ 2.80		$ 7.59	$ 9.41	$ 12.63
Provisional benefit related to remeasurement of net U.S. deferred tax liability, income tax expense amount recognized		$ 4	$ 4
Provisional benefit related to remeasurement of net U.S. deferred tax liability	$ (1,150)				$ (1,150)
Lease liability and related right-of-use asset		$ 13,000			$ 13,000
Stock Repurchase Program Number Of Shares Authorized To Be Repurchased							25,000,000
Number of Shares Repurchased		600,000		1,200,000	6,000,000	2,400,000
Treasury Stock Acquired, Average Cost Per Share		$ 168.43			$ 227.42
Payments for Repurchase of Common Stock		$ 93			$ 1,365	$ 558
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased		5,700,000			5,700,000
Dividends Payable, Date Declared					Feb. 15, 2019
Dividends Payable Amount Per Share		$ 0.65			$ 0.65
Dividends Payable, Date To Be Paid					Apr. 01, 2019
Dividends Payable, Date Of Record					Mar. 11, 2019
Business Realignment Activities [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Business realignment costs		$ 4
Business realignment costs, net of tax		$ 3
Diluted		$ 0.01