Summary of Significant Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016	Jun. 01, 2018
New Accounting Pronouncements
Retained earnings	$ 733.2	$ 727.9
Amount of recognized excess tax benefits as a reduction to income tax benefit	3.5	25.1	$ 23.4
Defined Benefit Pension Plans
New Accounting Pronouncements
Majority of our pension plans frozen and total service cost, including administrative expenses	2.4	$ 2.5
Improvements to Employee Share-Based Payment Accounting
New Accounting Pronouncements
Amount of recognized excess tax benefits as a reduction to income tax benefit	$ (2.9)
ASU 2014-09 | Adjustment
New Accounting Pronouncements
Retained earnings				$ (20.0)