Fair Value of Assets and Liabilities Measured on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Aug. 26, 2012	May 27, 2012
Assets:
Derivative assets	$ 97.3	$ 58.7
Available-for-sale securities	1.6	1.6
Deferred compensation assets	5.8	5.8
Total assets	104.7	66.1
Liabilities:
Derivative liabilities	221.9	215.4
Deferred compensation liabilities	30.1	27.1
Total liabilities	252.0	242.5
Level 1
Assets:
Derivative assets	11.2	13.8
Available-for-sale securities	1.6	1.6
Deferred compensation assets	5.8	5.8
Total assets	18.6	21.2
Liabilities:
Deferred compensation liabilities	30.1	27.1
Total liabilities	30.1	27.1
Level 2
Assets:
Derivative assets	86.1	44.9
Total assets	86.1	44.9
Liabilities:
Derivative liabilities	221.9	215.4
Total liabilities	$ 221.9	$ 215.4