Other Noncurrent Assets - License Fees (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jun. 30, 2011	May 31, 2016	May 31, 2015
Intangible assets
License fees		$ 15.5	$ 12.2
Exclusive distribution rights | Unison Industries
Intangible assets
Term of agreement	10 years
Amount agreed to be paid	$ 20.0
Amount paid	$ 7.0
Amount payable in each calendar year		1.3
Licensing Agreements
Intangible assets
Current portion of the deferred payments		1.3
Licensing Agreements | Unison Industries
Intangible assets
License fees		$ 8.8	$ 10.4
Amortization period		10 years
Long-term portion		$ 4.2