Other Assets (Details) (USD $)	Nov. 30, 2012		Aug. 31, 2012	Nov. 30, 2011		Nov. 30, 2012 Senior notes due March 15, 2020 at 8.00%	Feb. 07, 2012 Senior notes due March 15, 2020 at 8.00%	Nov. 30, 2012 Senior notes due September 15, 2022 at 7.50%	Jul. 31, 2012 Senior notes due September 15, 2022 at 7.50%
Other Assets [Line Items]
Cash surrender value of insurance contracts	$ 64,757,000			$ 59,718,000
Property and equipment, net	7,920,000			7,801,000
Debt issuance costs	14,563,000	[1]		4,219,000	[1]
Prepaid expenses	7,810,000			2,214,000
Net deferred tax assets	0		(1,200,000)	1,152,000
Total	95,050,000			75,104,000
Senior notes						$ 350,000,000	$ 350,000,000	$ 350,000,000	$ 350,000,000
Senior notes, rate						8.00%	8.00%	7.50%	7.50%

[1] The increase in debt issuance costs as of November 30, 2012 compared to November 30, 2011 primarily reflected the costs associated with our issuance of the $350 Million 8.00% Senior Notes and the $350 Million 7.50% Senior Notes during 2012.