Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Preferred Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock
Beginning Balance, shares (in shares) at Jun. 30, 2019		76,315,000				(12,604,000)
Beginning Balance at Jun. 30, 2019	$ 1,133,209	$ 382,423		$ (24,221)	$ 943,581	$ (168,574)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based and deferred compensation activities (in shares)		1,015,000				426,000
Share-based and deferred compensation activities	55,604	$ 71,050				$ (15,446)
Common Stock Repurchase (in shares)						(50,000)
Common Stock Repurchase	(1,625)					$ (1,625)
Shares issued and related to Finisar acquisitions (in shares)		26,713,000
Shares issued and related to Finisar acquisition	987,707	$ 987,707
Net (loss) earnings	(124,211)				(124,211)
Foreign currency translation adjustments	11,571			11,571
Change in fair value of interest rate swap, net of taxes	3,609			3,609
Pension adjustment, net of taxes	(167)			(167)
Ending Balance, shares (in shares) at Dec. 31, 2019		104,043,000				(13,080,000)
Ending Balance at Dec. 31, 2019	2,065,697	$ 1,441,180		(9,208)	819,370	$ (185,645)
Beginning Balance, shares (in shares) at Sep. 30, 2019		103,736,000				(12,855,000)
Beginning Balance at Sep. 30, 2019	2,131,194	$ 1,429,173		(37,156)	917,583	$ (178,406)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based and deferred compensation activities (in shares)		307,000				175,000
Share-based and deferred compensation activities	6,393	$ 12,007				$ (5,614)
Common Stock Repurchase (in shares)						(50,000)
Common Stock Repurchase	(1,625)					$ (1,625)
Net (loss) earnings	(98,213)				(98,213)
Foreign currency translation adjustments	24,590			24,590
Change in fair value of interest rate swap, net of taxes	3,609			3,609
Pension adjustment, net of taxes	(251)			(251)
Ending Balance, shares (in shares) at Dec. 31, 2019		104,043,000				(13,080,000)
Ending Balance at Dec. 31, 2019	2,065,697	$ 1,441,180		(9,208)	819,370	$ (185,645)
Beginning Balance, shares (in shares) at Jun. 30, 2020		105,916,000	0			(13,356,000)
Beginning Balance at Jun. 30, 2020	2,076,803	$ 1,486,947	$ 0	(87,383)	876,552	$ (199,313)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based and deferred compensation activities (in shares)		1,429,000				131,000
Share-based and deferred compensation activities	53,481	$ 60,297				$ (6,816)
Shares issued in July 2020 underwritten public offering (in shares)		10,698,000	2,300,000
Shares issued in July 2020 underwritten public offering	883,908	$ 438,589	$ 445,319
Net (loss) earnings	134,166				134,166
Foreign currency translation adjustments	99,591			99,591
Change in fair value of interest rate swap, net of taxes	2,299			2,299
Pension adjustment, net of taxes	0
Dividends	(13,435)				(13,435)
Ending Balance, shares (in shares) at Dec. 31, 2020		118,043,000	2,300,000			(13,487,000)
Ending Balance at Dec. 31, 2020	3,236,813	$ 1,985,833	$ 445,319	14,507	997,283	$ (206,129)
Beginning Balance, shares (in shares) at Sep. 30, 2020		117,189,000	2,300,000			(13,476,000)
Beginning Balance at Sep. 30, 2020	3,046,677	$ 1,942,300	$ 445,319	(52,414)	916,283	$ (204,811)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based and deferred compensation activities (in shares)		854,000				11,000
Share-based and deferred compensation activities	$ 42,215	$ 43,533				$ (1,318)
Common Stock Repurchase (in shares)	0
Net (loss) earnings	$ 87,900				87,900
Foreign currency translation adjustments	64,067			64,067
Change in fair value of interest rate swap, net of taxes	2,854			2,854
Pension adjustment, net of taxes	0
Dividends	(6,900)				(6,900)
Ending Balance, shares (in shares) at Dec. 31, 2020		118,043,000	2,300,000			(13,487,000)
Ending Balance at Dec. 31, 2020	$ 3,236,813	$ 1,985,833	$ 445,319	$ 14,507	$ 997,283	$ (206,129)