Variable Interest Entities - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Nov. 25, 2012	May 27, 2012
Variable Interest Entity [Line Items]
Price at which Ochoa has the right to put its equity interest	$ 38.0
Balance of promissory note due from joint venture	36.1
Long-term debt interest rate	3.25%
Debt instrument, lines of credit bear interest	2.00%
Line of credit with Lamb Weston BSW, Maximum Borrowing Capacity	15.0
Lamb Weston BSW [Member]
Variable Interest Entity [Line Items]
Acquisition of equity interest in Lamb Weston	49.99%
Lamb Weston RDO [Member]
Variable Interest Entity [Line Items]
Acquisition of equity interest in Lamb Weston	50.00%
Investment in Lamb Weston, maximum exposure	15.0	14.8
Owners' equity in capital structure of variable interest entity	26.8
Term borrowings from banks in capital structure of Lamb Weston, RDO	$ 44.5