Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Contributions to profit sharing retirement plan	$ 5,000	$ 4,300	$ 3,400
Common stock discount percentage from the prevailing market price	5.00%
Percentage of maximum employee subscription rate on base pay	10.00%
Contributions to the Compensation Plan by the employer	$ 2,731	2,432
Contributions to the Compensation Plan by the employer in fiscal year 2019	$ 2,700
Percentage of discretionary incentive compensation	100.00%
Contributions to the Compensation Plan by the employees	$ 1,100	$ 800	1,200
II-VI Performance Metals Defined Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions to the Compensation Plan by the employer			$ 0
Employee Stock
Defined Benefit Plan Disclosure [Line Items]
Common stock authorized for issuance under the Plan	1,600,000
Common stock available for purchase under the plan	462,798	477,949

Discretionary employer contributions to employee benefit plans.

No definition available.

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- Definition

Deferred compensation arrangement with individual employee contribution.

+ References

No definition available.

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- Definition

Deferred compensation plan designated to allow officers and key employees of the company to defer receipt of compensation in percentage.

+ References

No definition available.

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- Definition

Amount of contribution received by defined benefit plan from employer which increases plan assets.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of contributions expected to be received by defined benefit plan from employer in next fiscal year following latest fiscal year.

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- Definition

Discount rate from fair value on offering date that participants pay for shares.

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- Definition

The highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

+ References

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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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