Long-Term Indebtedness (Details) - USD ($) $ in Thousands	May. 31, 2015	Aug. 31, 2014
Debt Instrument [Line Items]
Total Senior Indebtedness	$ 600,000	$ 390,000
Less: current maturities of long-term debt	0	(4,500)
Total long-term debt, less current maturities	600,000	385,500
Line of Credit
Debt Instrument [Line Items]
Total Senior Indebtedness	300,000	90,000
Line of Credit | Senior Credit Facility - Revolver
Debt Instrument [Line Items]
Total Senior Indebtedness	0	0
Line of Credit | Senior Credit Facility - Term Loan
Debt Instrument [Line Items]
Total Senior Indebtedness	300,000	90,000
Senior Notes | 5.625% Senior Notes
Debt Instrument [Line Items]
Total Senior Indebtedness	$ 300,000	$ 300,000