Income Taxes (Narrative) (Details) (USD $)	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Income Tax Contingency [Line Items]
Additional income tax provision	$ 1,559,000
Operating loss carryforwards, expiration date	beginning in 2012
State net operating loss carryforwards, valuation allowance	7,400,000	6,400,000
Unrecognized tax benefits	5,451,000	4,775,000	5,628,000
Unrecognized tax benefits, interest and penalty	746,000
Increase in unrecognized tax benefits	676,000
Unrecognized tax benefits favorably impact the effective tax rate	1,862,000
Income taxes receivable, noncurrent	10,300,000
Income taxes receivable		12,776,000
Maximum [Member]
Income Tax Contingency [Line Items]
Change in liability for unrecognized tax benefits during the next 12 months	(4,872,000)
Minimum [Member]
Income Tax Contingency [Line Items]
Change in liability for unrecognized tax benefits during the next 12 months	$ 123,000