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Debt - Additional Information (Detail) (USD $)
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3 Months Ended | 6 Months Ended | 1 Months Ended | |||||||||||||||
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Feb. 28, 2013
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Feb. 28, 2013
Minimum
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Feb. 28, 2013
Maximum
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Feb. 28, 2013
Libor Rate
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Feb. 28, 2013
Libor Rate
Minimum
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Feb. 28, 2013
Libor Rate
Maximum
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Feb. 28, 2013
Base Rate
Minimum
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Feb. 28, 2013
Base Rate
Maximum
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Feb. 28, 2013
Revolving Credit Facility
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Feb. 28, 2013
Senior Credit Facility - Term Loan
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Feb. 28, 2013
Senior Credit Facility - Term Loan
Starting on March 31, 2012
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Feb. 28, 2013
Senior Credit Facility - Term Loan
starting on March 31, 2013
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Feb. 28, 2013
Line of Credit
Senior Credit Facility - Revolver
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Feb. 28, 2013
Senior Notes
5.625% Senior Notes
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Apr. 16, 2012
Senior Notes
5.625% Senior Notes
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Apr. 16, 2012
Senior Notes
6.875% Senior Notes
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Mar. 31, 2012
Convertible Notes Payable
2% Convertible Notes
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Feb. 28, 2013
Convertible Notes Payable
2% Convertible Notes
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| Debt Instrument [Line Items] | ||||||||||||||||||
| Maximum borrowing capacity | $ 600,000,000 | $ 100,000,000 | ||||||||||||||||
| Senior credit facility expansion option, available | 300,000,000 | |||||||||||||||||
| Debt instrument, interest rate over variable rate | 1.25% | 1.25% | 2.50% | 0.25% | 1.50% | |||||||||||||
| Debt Instrument, actual interest rate | 1.50% | |||||||||||||||||
| Percentage of non-use fee, annually | 0.20% | 0.40% | ||||||||||||||||
| Unused credit line | 596,400,000 | |||||||||||||||||
| Quarterly installments, payable on term loan | 1,250,000 | 2,500,000 | ||||||||||||||||
| Leverage ratio | 3.75 | |||||||||||||||||
| Fixed charge coverage ratio | 1.50 | |||||||||||||||||
| Senior Notes | 300,000,000 | 250,000,000 | ||||||||||||||||
| Debt instrument, interest rate | 5.625% | 5.625% | 6.875% | 2.00% | 2.00% | |||||||||||||
| Debt instrument, redemption price percentage | 104.00% | |||||||||||||||||
| Debt instrument, repurchase amount | 260,400,000 | |||||||||||||||||
| Debt conversion converted remaining instrument amount | 117,600,000 | |||||||||||||||||
| Conversion ratio per $1,000 of principal | 50.6554 | |||||||||||||||||
| Number of shares issued due to calling of convertible notes | 5,951,440 | |||||||||||||||||
| Repurchases of 2% Convertible Notes | $ 100,000 | |||||||||||||||||