Summary of Geographic Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2011	Feb. 28, 2011	Nov. 30, 2010	Aug. 31, 2012		Aug. 31, 2011		Aug. 31, 2010
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 443,534	$ 507,797	$ 458,186	$ 398,199	$ 442,736	$ 317,280	$ 284,340	$ 198,934	$ 1,807,716	[1]	$ 1,243,290	[1]	$ 756,280	[1]
Assets	1,384,544				1,301,655				1,384,544		1,301,655		1,072,888
UNITED STATES
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									1,642,348	[1]	1,103,423	[1]	659,697	[1]
Assets	982,078				1,000,249				982,078		1,000,249		918,553
Foreign
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									165,368	[1]	139,867	[1]	96,583	[1]
CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Assets	718								718
Mexico
Segment Reporting, Revenue Reconciling Item [Line Items]
Assets	323,318				228,406				323,318		228,406		115,721
Europe
Segment Reporting, Revenue Reconciling Item [Line Items]
Assets	$ 78,430				$ 73,000				$ 78,430		$ 73,000		$ 38,614

[1] Revenue is presented on the basis of geographic location of customers.