Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Contributions to profit sharing retirement plan	$ 4,300	$ 3,400	$ 2,800
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	$ 2,432	2,043
Contributions to the Compensation Plan by the employer in fiscal year 2018	$ 2,600
Percentage of discretionary incentive compensation	100.00%
Contributions to the Compensation Plan by the employees	$ 800	1,200	700
II-VI Performance Metals Defined Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions to the Compensation Plan by the employer		$ 0	$ 0
II-VI Performance Metals Defined Benefit Plan | Dr. Mattera
Defined Benefit Plan Disclosure [Line Items]
Contributions to the Compensation Plan by the employer	$ 100
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	477,949	492,913