Fair Value Of Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	Feb. 29, 2016	Aug. 31, 2015
Fair Value Disclosure [Line Items]
Cash equivalents carried at cost	$ 43.6	$ 41.1
2013 and 2011 Fixed Rate Notes [Member]
Fair Value Disclosure [Line Items]
Long-term debt, fair value	423.2
Long-term debt, carrying value, including accrued interest	423.2
2011 Variable Rate Notes [Member]
Fair Value Disclosure [Line Items]
Long-term debt, fair value	72.1
Long-term debt, carrying value, including accrued interest	$ 72.1