Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2015	Jan. 31, 2014
Income Taxes [Abstract]
Effective tax rate	27.00%	22.10%	27.30%	27.60%
Tax benefit associated with the favorable settlement of a tax audit		$ 6.4
Unrecognized tax benefits	16.3		16.3
Accrued interest and penalties on unrecognized tax benefits	1.7		1.7
Statute of limitations period, average, years			5 years
Maximum possible reduction in amount of unrecognized tax benefits			$ 1.0
Unrecognized tax benefits potential expiration period			12 months