Financial Information of Company's Operation by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Revenues	$ 241,470	$ 205,105	$ 191,434	$ 189,207	$ 196,683	$ 182,709	$ 176,736	$ 185,833	$ 827,216	$ 741,961	$ 683,261
Operating income (loss)									91,813	76,799	46,486
Interest expense	(1,066)	(769)	(597)	(649)	(777)	(844)	(1,038)	(1,204)	(3,081)	(3,863)	(4,479)
Other income, net	429	(1,257)	994	1,057	97	(1,534)	9,295	(1,682)	1,223	6,176	3,634
Income taxes	(13,934)	(2,426)	(3,187)	(4,922)	(5,464)	(773)	(2,692)	(4,208)	(24,469)	(13,137)	(7,325)
Earnings from discontinued operation											133
Net earnings	14,343	$ 14,938	$ 18,991	$ 17,214	17,069	$ 14,508	$ 22,096	$ 12,302	65,486	65,975	38,449
Depreciation and amortization									56,663	53,083	53,098
Expenditures for property, plant & equipment									58,170	52,313	29,220
Segment assets	1,212,591				1,058,164				1,212,591	1,058,164
Equity investment	11,354				11,914				11,354	11,914
Goodwill	233,755				195,894				233,755	195,894	196,145
Eliminations
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Inter-segment revenues									(43,645)	(43,556)	(31,358)
II-VI Laser Solutions
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Goodwill	84,105				43,578				84,105	43,578	44,041
II-VI Laser Solutions | Operating Segments
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Revenues									303,002	287,881	254,342
Inter-segment revenues									24,290	21,021	9,825
Operating income (loss)									36,184	55,039	24,457
Depreciation and amortization									17,222	14,127	15,018
Expenditures for property, plant & equipment									25,620	27,349	11,797
Segment assets	470,364				330,308				470,364	330,308
Goodwill	84,105				43,578				84,105	43,578
II-VI Photonics
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Goodwill	96,760				99,426				96,760	99,426	99,214
II-VI Photonics | Operating Segments
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Revenues									325,879	260,825	216,493
Inter-segment revenues									12,081	13,210	9,533
Operating income (loss)									37,849	7,208	(113)
Depreciation and amortization									19,855	21,073	20,123
Expenditures for property, plant & equipment									21,096	11,324	8,359
Segment assets	467,486				450,763				467,486	450,763
Goodwill	96,760				99,426				96,760	99,426
II- VI Performance Products
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Goodwill	52,890				52,890				52,890	52,890	52,890
II- VI Performance Products | Operating Segments
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Revenues									198,335	193,255	212,426
Inter-segment revenues									7,274	9,325	12,000
Operating income (loss)									17,780	14,552	22,142
Depreciation and amortization									19,586	17,883	17,957
Expenditures for property, plant & equipment									11,454	13,640	$ 9,064
Segment assets	274,741				277,093				274,741	277,093
Equity investment	11,354				11,914				11,354	11,914
Goodwill	$ 52,890				$ 52,890				$ 52,890	$ 52,890