Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2016	Aug. 31, 2015	Aug. 31, 2014
Operating Loss Carryforwards [Line Items]
Federal	$ (30,758)	$ 29,348	$ (23,444)
Income (Loss) from Continuing Operations before Income Taxes, Domestic	490,800	824,900	1,200,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	0		0
Operating Loss Carryforwards	676,600
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	425,700
Change in valuation allowance for deferred tax asset	40,600
Current State and Local Tax Expense (Benefit)	3,972	3,891	31,203
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	0	0	$ 35,718
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	0	0
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Federal	25,600
Current assets
Operating Loss Carryforwards [Line Items]
Net deferred tax assets		85,000
Other Assets [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent		1,600
Net deferred tax assets	2,500
Alternative Minimum Tax Credit [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	5,600
General Business Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	64,500
State tax credits [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	133,500
NCRA [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	133,500	$ 62,200
Change in valuation allowance for deferred tax asset	$ 55,600