Supplementary Financial Information, Common Stock Price High And Low Sales Price for Each Quarter (Details) - $ / shares	3 Months Ended								12 Months Ended
	Aug. 31, 2015	May. 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	May. 31, 2014	Feb. 28, 2014	Nov. 30, 2013	Aug. 31, 2015	Aug. 31, 2014
Supplementary Financial Information [Abstract]
Common stock price for quarter per Consolidated Transaction Reporting System, High	$ 97.30	$ 93.42	$ 83.77	$ 69.37	$ 76.39	$ 71.97	$ 69.84	$ 60.93	$ 97.30	$ 76.39
Common stock price for quarter per Consolidated Transaction Reporting System, Low	$ 76.01	$ 81.01	$ 66.46	$ 58.39	$ 57.75	$ 62.80	$ 54.86	$ 48.18	$ 58.39	$ 48.18