Stock Plans (Schedule of net cash proceeds from the exercise of stock options less shares used for withholding taxes and the intrisic value of options exercised) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Feb. 22, 2015	Feb. 23, 2014
Stock Plans [Abstract]
Net cash proceeds	$ 103.1	$ 42.6
Intrinsic value of options exercised	$ 121.6	$ 86.5