Retirement Plans - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	$ 1,068	$ 1,168
Benefits and administrative expenses	51,753	40,623	39,944
Expected payments for fiscal year 2013	302
Defined Contribution Pension Plan 401k
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer matching contribution percentage of employee contributions of eligible compensation	4.00%	4.00%	4.00%
Company's contributions to the Plan	2,900	2,729	2,632
Defined Contribution Pension Plan 401k \| Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage employees may contribute of their eligible compensation to the plan	1.00%
Defined Contribution Pension Plan 401k \| Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage employees may contribute of their eligible compensation to the plan	80.00%
Anrad Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected to be amortized, net prior service cost	10
Expected to be amortized, net transition asset	27
Expected to be amortized, net actuarial loss	359
Amortized amounts of net prior service cost	10
Amortized amounts of net transition asset	26
Amortized amounts of net actuarial loss	210
Employer contributions	1,068	1,168	1,256
Benefits and administrative expenses	107	209	169
Anrad Plan \| General and Administrative Expense
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected contributions for fiscal year 2013	1,265
Expected payments for fiscal year 2013	408
Anrad Plan \| Other Postretirement Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
ABO balances	$ 7,743	$ 5,952

Defined Benefit Plan, Employee Contribution, Percentage

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- Definition

Other Comprehensive Income Amortization Of Defined Benefit Plan Transition Asset Obligation Before Tax

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Other Comprehensive Income, Amortization of Net Actuarial Gain (Loss), Before Tax

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- Definition

The amounts in accumulated other comprehensive income related to gains and losses that are not recognized immediately and are expected to be recognized as components of net periodic benefit cost over the next fiscal year that follows the most recent annual statement of financial position presented.

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The amounts in accumulated other comprehensive income related to prior service cost or credit expected to be recognized as components of net periodic benefit cost over the next fiscal year that follows the most recent annual statement of financial position presented.

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- Definition

The amounts in accumulated other comprehensive income related to transition assets (obligations), origination from the adoption of FAS 87 and 106, expected to be recognized as components of net periodic benefit cost over the next fiscal year that follows the most recent annual statement of financial position presented.

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- Definition

1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date.

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- Definition

The increase in the fair value of plan assets from contributions made by the employer.

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- Definition

The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.

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- Definition

Amount of benefits expected to be paid in the next fiscal year following the latest fiscal year from a defined benefit plan.

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Maximum percentage of employee gross pay, by the terms of the plan, that the employer may contribute to a defined contribution plan.

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- Definition

The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Before tax amount of the income statement impact of the reclassification adjustment for prior service costs recognized as a component of net period benefit cost.

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- Definition

The amount of pension benefit costs recognized during the period for (1) defined benefit plans and (2) defined contribution plans. For defined benefit plans, pension expense includes the following components: service cost, interest cost, expected return on plan assets, gain (loss) on plan assets, prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments. For defined contribution plans, the pension expense generally equals the firm's contribution to employees' accounts (if the firm contributes) during the period.

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