Summary of Significant Accounting and Reporting Policies (Accounting for Stock-Based Compensation) (Details) (USD $)	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009
Stock-based compensation expense before income tax benefit	$ 5,357,000	$ 8,716,000	$ 9,576,000
Income tax benefit	(1,913,000)	(3,201,000)	(3,201,000)
Net stock-based compensation expense	3,444,000	5,515,000	6,375,000
Total stock-based compensation expense related to employee stock purchase plan	270,000	307,000	374,000
Required fair value remeasurement of liability-classified stock appreciation rights	(52,000)	(41,000)	(73,000)
Stock-based compensation capitalized and included in ending inventory	117,000	159,000	277,000
Per share weighted average grant date fair value of stock based awards granted	$ 6.51	$ 10.47	$ 12.60
Fair Value Assumptions [Abstract]
Expected dividend yield	3.62%	0.00%	0.00%
Expected volatility	36.31%	38.00%	40.36%
Risk free interest rate	1.58%	1.99%	2.19%
Expected life (in years)	5.10	5.01	3.61
Share-based compensation arrangement by share-based payment award, plan modification, incremental compensation cost		1,396,000
Number of previously granted stock based awards modified		601,875
Expected dividend yield on modified stock-based awards		0.00%
Expected life (in years) on modified stock-based awards		1.59
Expected volatility on modified stock-based awards		40.98%
Risk free interest rate on modified stock-based awards		0.47%
Number of employees previously granted stock based awards		78
Contractual term on stock-based awards granted	five or ten years
Vesting period on stock-based awards granted	three or five years
Accrued expense related to the cash settlement of liability-classified stock appreciation rights	22,000	74,000	115,000
Targeted annual dividend per share	$ 1.00
Actual income tax benefit recorded for the tax deductions relating to the exercise of stock based awards	306,000	484,000	3,805,000
Less: Tax benefit initially recognized on exercised stock-based awards vesting subsequent to the adoption of accounting standards that require us to expense stock-based awards, excluding income tax shortfalls	(81,000)	(227,000)	(1,275,000)
Excess income tax benefit recorded as an increase to additional paid-in capital	225,000	257,000	2,530,000
Less: Tax benefit initially disclosed but not previously recognized on exercised equity-classified stock-based awards vesting prior to the adoption of accounting standards that require us to expense stock-based awards		(7,000)
Excess income tax benefit from exercised equity classified stock based awards reported as cash flow from financing activities in our Consolidated Statements of Cash Flows	225,000	250,000	2,530,000
Total remaining unrecognized compensation cost related to the unvested stock-based awards	9,586,000
Estimated forfeitures related to unvested stock-based awards	480,000
Net compensation cost expected to be recognized over a weighted average number of years	3.7
Hypothetical tax benefits related to stock-based awards	24,118,000
Reduction to APIC due to reversal of deferred tax assets associated with expired and unexercised stock-based awards	1,785,000
Cost of Sales [Member]
Stock-based compensation expense before income tax benefit	410,000	828,000	812,000
Selling, General and Administrative Expenses [Member]
Stock-based compensation expense before income tax benefit	3,976,000	6,317,000	7,080,000
Research and Development Expense [Member]
Stock-based compensation expense before income tax benefit	$ 971,000	$ 1,571,000	$ 1,684,000