BUSINESS SEGMENTS AND RELATED INFORMATION (Allocation of Net Derivative Gains (Losses) from Economic Hedges of Forecasted Commodity Consumption and Foreign Currency Risk (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Aug. 25, 2013	Aug. 26, 2012
Operating Statistics [Line Items]
Derivative gain (loss) on derivative, net	$ (20.7)
Commodity contracts
Operating Statistics [Line Items]
Derivative gain (loss) on derivative, net	(17.5)	120.2
Commodity contracts | Consumer Foods
Operating Statistics [Line Items]
Derivative gain (loss) on derivative, net	2.0	(3.9)
Commodity contracts | Commercial Foods
Operating Statistics [Line Items]
Derivative gain (loss) on derivative, net	2.0	(6.1)
Commodity contracts | Ralcorp Food Group
Operating Statistics [Line Items]
Derivative gain (loss) on derivative, net	(0.4)	0
Commodity contracts | Ralcorp Frozen Bakery Products
Operating Statistics [Line Items]
Derivative gain (loss) on derivative, net	(0.4)	0
Operating Segments [Member] | Commodity contracts
Operating Statistics [Line Items]
Derivative gain (loss) on derivative, net	3.2	(10.0)
Segment Reconciling Items | Commodity contracts
Operating Statistics [Line Items]
Derivative gain (loss) on derivative, net	$ (20.7)	$ 130.2