Computation of Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]
Earnings from continuing operations									$ 65,975	$ 38,316	$ 57,602
Earnings (loss) from discontinued operation							$ 131	$ 2		133	(6,789)
Net Earnings Attributable to II-VI Incorporated									$ 65,975	$ 38,449	$ 50,813
Weighted average shares									61,219	62,248	62,411
Basic earnings (loss) per common share:
Continuing Operations					$ 0.21	$ 0.14	$ 0.12	$ 0.16	$ 1.08	$ 0.62	$ 0.92
Discontinued operation											(0.11)
Consolidated	$ 0.28	$ 0.24	$ 0.36	$ 0.20	0.21	0.14	0.12	0.16	$ 1.08	$ 0.62	$ 0.81
Dilutive effect of common stock equivalents									1,367	1,438	1,473
Diluted weighted average common shares									62,586	63,686	63,884
Diluted earnings (loss) per common share:
Continuing Operations					0.20	0.13	0.12	0.15	$ 1.05	$ 0.60	$ 0.90
Discontinued operation											(0.11)
Consolidated	$ 0.27	$ 0.23	$ 0.35	$ 0.20	$ 0.20	$ 0.13	$ 0.12	$ 0.15	$ 1.05	$ 0.60	$ 0.80