Segment and Geographic Reporting - Financial Information of Company's Operation by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Net revenues	$ 746,290	$ 627,041	$ 666,331	$ 340,409	$ 362,728	$ 342,496	$ 342,839	$ 314,433	$ 2,380,071	$ 1,362,496	$ 1,158,794
Inter-segment revenues									0	0	0
Operating income (loss)									39,479	148,668	136,763
Interest expense	(25,521)	(28,530)	(28,390)	(6,968)	(5,606)	(5,647)	(5,580)	(5,584)	(89,409)	(22,417)	(18,352)
Other income (expense), net	(1,264)	(7,168)	(487)	(5,079)	(384)	1,532	701	713	(13,998)	2,562	3,783
Income taxes	10,550	(27,417)	9,242	4,524	(6,701)	(2,377)	(6,025)	(6,193)	(3,101)	(21,296)	(34,192)
Net Earnings (Loss)	51,261	$ 5,921	$ (98,213)	$ (25,998)	28,028	$ 24,638	$ 28,702	$ 26,149	(67,029)	107,517	88,002
Depreciation and amortization									220,882	92,365	80,770
Expenditures for property, plant & equipment									136,877	128,750	161,323
Segment assets	5,234,714				1,953,773				5,234,714	1,953,773
Goodwill	1,239,009				319,778				1,239,009	319,778	270,678
Photonic Solutions
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Goodwill	1,052,494				134,057				1,052,494	134,057	109,670
Compound Semiconductors
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Goodwill	186,515				185,721				186,515	185,721	161,008
Operating Segments | Photonic Solutions
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Net revenues									1,536,790	638,889	486,485
Inter-segment revenues									31,515	12,568	24,867
Operating income (loss)									49,930	81,898	63,152
Interest expense									0	0	0
Other income (expense), net									0	0	0
Income taxes									0	0	0
Net Earnings (Loss)									0	0	0
Depreciation and amortization									112,203	26,273	23,242
Expenditures for property, plant & equipment									45,795	44,851	36,122
Segment assets	3,502,467				681,610				3,502,467	681,610
Goodwill	1,052,494				134,057				1,052,494	134,057
Operating Segments | Compound Semiconductors
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Net revenues									821,230	723,607	672,309
Inter-segment revenues									164,884	94,405	37,723
Operating income (loss)									62,279	82,414	73,611
Interest expense									0	0	0
Other income (expense), net									0	0	0
Income taxes									0	0	0
Net Earnings (Loss)									0	0	0
Depreciation and amortization									104,936	66,092	57,528
Expenditures for property, plant & equipment									88,318	83,899	125,201
Segment assets	1,732,247				1,272,163				1,732,247	1,272,163
Goodwill	186,515				185,721				186,515	185,721
Unallocated & Other
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Net revenues									22,051	0	0
Inter-segment revenues									(196,399)	(106,973)	(62,591)
Operating income (loss)									(72,730)	(15,643)	0
Interest expense									0	0	0
Other income (expense), net									0	0	0
Income taxes									0	0	0
Net Earnings (Loss)									0	0	0
Depreciation and amortization									3,743	0	0
Expenditures for property, plant & equipment									2,764	0	$ 0
Segment assets	0				0				0	0
Goodwill	$ 0				$ 0				$ 0	$ 0