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The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period.

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No definition available.

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Number of share options (or share units) exercised during the current period.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

+ References

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Weighted average price of options that were either forfeited or expired.

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Gross number of share options (or share units) granted during the period.

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No definition available.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

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Stock-based Compensation (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Apr. 30, 2012	Apr. 30, 2011	Apr. 30, 2012	Apr. 30, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 5,388	$ 5,077	$ 16,414	$ 14,193
Number Of Options [Roll Forward]
Outstanding at July 31, 2011			16,705
Grants of options			840
Exercises			(1,034)
Forfeitures or expirations			(39)
Outstanding at April 30, 2012	16,472		16,472
Exercisable at April 30, 2012	9,801		9,801
Weighted Average Exercise Price [Roll Forward]
Outstanding at July 31, 2011			$ 15.50
Grants of options			$ 22.93
Exercises			$ 12.56
Forfeitures or expirations			$ 16.67
Outstanding at April 30, 2012	$ 16.07		$ 16.07
Exercisable at April 30, 2012	$ 15.10		$ 15.10
Weighted-Average Remaining Contractual Term [Roll Forward]
Outstanding			6 years 9 months
Exercisable			6 years 1 month
Aggregate Intrinsic Value [Roll Forward]
Outstanding at April 30, 2012	170,246		170,246
Exercisable at April 30, 2012	110,812		110,812
General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	4,573	4,834	14,216	13,395
Yard operations
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 815	$ 243	$ 2,198	$ 798