Summary of Significant Accounting Policies - Treasury Stock (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	May 29, 2015	May 31, 2017	May 31, 2016	May 31, 2015
Repurchase of treasury shares		$ 19.8	$ 18.8	$ 151.5
Shares repurchased (in shares)	4,185,960
Change in treasury stock due to restricted stock grants		5.4	(0.3)	4.2
Change in treasury stock due to exercise of stock options, net of shares withheld to satisfy statutory tax obligations		12.0	6.7	6.3
Share repurchase price (in dollars per share)	$ 31.90
Cash tender offer amount	$ 133.5
Fees and expenses	$ 1.2
Shares repurchased		16.8
Change in treasury stock due to restricted stock awards and exercise of stock options, net of shares withheld to satisfy statutory tax obligations				3.6
Treasury Stock
Total increase (decrease) in treasury stock		12.2	21.3
Repurchase of treasury shares		19.8	18.8	151.5
Change in treasury stock due to restricted stock grants		(1.3)	(4.8)	(0.7)
Change in treasury stock due to exercise of stock options, net of shares withheld to satisfy statutory tax obligations		$ 8.9	$ 2.3	$ 4.2