Description of Business, Basis of Presentation, and Significant Accounting Policies (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 29, 2016	Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015	May. 31, 2015	Dec. 31, 2014
Description of Business, Basis of Presentation, and Significant Accounting Policies (Textual)
Disclosure on geographic areas, Description of revenue from external customers				revenue within Germany, which represented less than one percent of the Company's total revenue	revenue within Germany, which represented less than one percent of the Company's total revenue
Disclosure on geographic areas, Long-lived assets				Long-lived assets in Germany are insignificant in relation to total long-lived assets of the Company		Long-lived assets in Germany are insignificant in relation to total long-lived assets of the Company
Allowance for doubtful accounts	$ 4.1	$ 4.1		$ 4.1		$ 1.4
Trade accounts receivable, net	175.4	175.4		175.4		176.6
Purchased accounts receivable, net	178.0	178.0		178.0
Maximum individual workers' compensation claims liability				1.3		$ 1.0
Maximum individual claims liability health insurance	$ 0.3						$ 0.3
Stock-based compensation costs recognized		$ 8.6	$ 8.6	$ 26.1	$ 24.0