Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Common Stock	Capital Surplus	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total
Increase (Decrease) in Stockholders' Equity
Cumulative effect adjustment upon adoption of ASU 606 | ASU 2014-09			$ (20.4)			$ (20.4)
Balance at May. 31, 2018	$ 45.3	$ 470.5	733.2	$ (280.7)	$ (32.0)	936.3
Increase (Decrease) in Stockholders' Equity
Net income			22.1			22.1
Cash dividends			(5.3)			(5.3)
Stock option activity		1.6		3.8		5.4
Restricted stock activity		(1.3)		(0.6)		(1.9)
Other comprehensive loss, net of tax					(0.6)	(0.6)
Balance at Nov. 30, 2018	$ 45.3	$ 470.8	$ 729.6	$ (277.5)	$ (32.6)	$ 935.6