Share-based Compensation Plans (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended				12 Months Ended	6 Months Ended				12 Months Ended	6 Months Ended		12 Months Ended
	Feb. 28, 2014	Feb. 28, 2013	Feb. 28, 2014	Feb. 28, 2013	Feb. 28, 2014 SARs [Member]	Feb. 28, 2013 SARs [Member]	Aug. 31, 2013 SARs [Member]	Feb. 28, 2014 RSUs And PSUs [Member]	Feb. 28, 2013 RSUs And PSUs [Member]	Feb. 28, 2014 Certain RSUs [Member]	Feb. 28, 2014 PSU [Member]	Aug. 31, 2013 PSU [Member]	Feb. 28, 2014 Share-Based Liability Awards [Member]	Feb. 28, 2013 Share-Based Liability Awards [Member]	Aug. 31, 2013 RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted								1,200,000	1,600,000				59,565	234,109
Weighted average grant-date fair value								$ 16.89	$ 13.44
SARs, granted, number					0	200,000
Granted, weighted average exercise price						$ 14.25
Vesting period in years							3 years	3 years		4 years	3 years	3 years			3 years
Contractual term					7 years
Share-based compensation expense	$ 5.3	$ 3.6	$ 10.8	$ 7.2
Equivalent number of shares outstanding													1,722,173
Equivalent number of shares expected to vest													1,637,113