Debt (Schedule of credit facilities) (Details) € in Millions, $ in Billions	9 Months Ended
	Feb. 28, 2016 EUR (€)	Feb. 28, 2016 USD ($)
Line Of Credit Facility [Line Items]
Facility Amount		$ 3.3
Borrowed Amount		0.3
Committed Credit Facilities [Member]
Line Of Credit Facility [Line Items]
Facility Amount		2.9
Borrowed Amount		$ 0.2
Minimum fixed charge coverage ratio	2.5	2.5
Compliance with credit facility covenants	As of February 28, 2016, we were in compliance with all of these covenants.
Committed Credit Facilities [Member] | Yoplait SAS [Member]
Line Of Credit Facility [Line Items]
Facility Amount | €	€ 200.0
Expiration date of credit facility	Jun. 30, 2019
Line of Credit Expiring April 2017 [Member]
Line Of Credit Facility [Line Items]
Facility Amount		$ 1.7
Borrowed Amount		0.0
Expiration date of credit facility	Apr. 30, 2017
Line of Credit Expiring May 2019 [Member]
Line Of Credit Facility [Line Items]
Facility Amount		1.0
Borrowed Amount		0.0
Expiration date of credit facility	May 31, 2019
Line of Credit Expiring June 2019 [Member]
Line Of Credit Facility [Line Items]
Facility Amount		0.2
Borrowed Amount		0.2
Expiration date of credit facility	Jun. 30, 2019
Uncommitted Credit Facilities [Member]
Line Of Credit Facility [Line Items]
Facility Amount		0.4
Borrowed Amount		$ 0.1