Summary of Significant Accounting Policies - Goodwill and Other Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Feb. 28, 2015 Refineries	Feb. 28, 2014	Feb. 28, 2015 Refineries	Feb. 28, 2014
Finite-Lived Intangible Assets [Line Items]
Number of Refineries	2		2
Expenditures for Major Repairs			$ 8,347	$ 0
Capitalized Maintenance Expense, Deferred During the Period	$ 7,200	$ 0	$ 8,300
Minimum [Member] | Major Maintenance Activities Requiring Shutdown [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			2 years
Maximum [Member] | Major Maintenance Activities Requiring Shutdown [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			4 years