Debt and Lines of Credit - Lines of Credit (Details) (USD $)						12 Months Ended	0 Months Ended	12 Months Ended
	Aug. 31, 2013 Revolving Credit Facility	Aug. 31, 2013 Lines of Credit	Aug. 31, 2013 Lines of Credit Revolving Credit Facility	Jan. 31, 2012 Lines of Credit Revolving Credit Facility	Oct. 19, 2007 Lines of Credit Revolving Credit Facility	Aug. 31, 2013 Maximum Lines of Credit Revolving Credit Facility	Jan. 30, 2012 Maximum Lines of Credit Prior Facility	Aug. 31, 2013 Minimum Lines of Credit Revolving Credit Facility
Line of Credit Facility [Line Items]
Executed revolving credit facility				$ 250,000,000.0	$ 250,000,000.0
Write-off of deferred issuance costs							100,000
Maximum Leverage Ratio			3.50
Minimum Interest Coverage Ratio			2.50
Applicable margins as determined by leverage ratio						1.65%		1.075%
Commitment fees rate						0.35%		0.175%
Outstanding letters of credit	5,700,000	9,900,000	250,000,000.0
Additional borrowing capacity under revolving credit facility			$ 244,300,000