Retirement Plans - Schedule of Amounts Recognized in Other Comprehensive Income ("OCI") for All Plans (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2017	May 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive Income Loss Amortization Adjustment From AOCI Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax	$ 75	$ 80
U.S. Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive Income Loss Amortization Adjustment From AOCI Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax	118	118
Total recognized in OCI, Gross Amount	118	118
Other Comprehensive Income Loss Amortization Adjustment From AOCI Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax	74	74
Total recognized in OCI, Net of Tax Amount	74	74
International Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net (gain) loss and other arising during period, Gross Amount	1
Other Comprehensive Income Loss Amortization Adjustment From AOCI Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax	2	3
Total recognized in OCI, Gross Amount	3	3
Net (gain) loss and other arising during period, Net of Tax Amount	1
Other Comprehensive Income Loss Amortization Adjustment From AOCI Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax	2	2
Total recognized in OCI, Net of Tax Amount	3	$ 2
Postretirement Healthcare Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net (gain) loss and other arising during period, Gross Amount	(3)
Total recognized in OCI, Gross Amount	(3)
Net (gain) loss and other arising during period, Net of Tax Amount	(2)
Total recognized in OCI, Net of Tax Amount	$ (2)