Debt - Additional Information (Detail)		3 Months Ended	9 Months Ended
	Sep. 24, 2019 USD ($) d	Sep. 30, 2018 USD ($)	Mar. 31, 2020 USD ($) $ / shares	Mar. 31, 2019 USD ($)	Oct. 23, 2019 USD ($)	Jun. 30, 2019 USD ($)	Aug. 31, 2017 USD ($)
Line of Credit Facility [Line Items]
Debt extinguishment costs			$ 3,960,000	$ 0
Available credit under lines of credit			$ 358,600,000
Weighted average interest rate of total borrowings			3.70%	1.60%
0.25% Convertible Senior Note Due 2022
Line of Credit Facility [Line Items]
Debt instrument, interest rate			0.25%	0.25%
Unamortized discount amount			$ 29,700,000			$ 38,300,000
Amortization period			3 years
Aggregate principal amount							$ 345,000,000
Debt instrument conversion rate, shares issued per $1,000 principal amount (in usd per share)			21.25
Debt instrument conversion, principal amount of each note converted			$ 1,000
Debt instrument conversion, conversion price per share (in usd per share) | $ / shares			$ 47.06
Debt instrument conversion, If-converted value of notes		$ 268,000,000.0	$ 208,900,000
Effective interest rate			4.50%
0.50% Finisar Convertible Notes
Line of Credit Facility [Line Items]
Obligated to repay outstanding principal in quarterly installments, percentage	100.00%
Debt instrument, interest rate	0.50%		0.50%
Aggregate principal amount	$ 560,100,000
Debt instrument, repurchase amount					$ 561,100,000
Line of credit, outstanding			$ 14,900,000
Bank of America, N.A.
Line of Credit Facility [Line Items]
Letter of credit sub-facility maximum borrowing capacity	25,000,000.0
Swing loan sub-facility maximum initial borrowing capacity	20,000,000.0
Senior Secured Credit Facility | Bank of America, N.A.
Line of Credit Facility [Line Items]
Aggregate principal amount	2,425,000,000
Term A Loan Facility
Line of Credit Facility [Line Items]
Proceeds from term loan	561,000,000.0
Term A Loan Facility | Bank of America, N.A.
Line of Credit Facility [Line Items]
Aggregate principal amount	$ 1,255,000,000
Debt agreement term	5 years
Obligated to repay outstanding principal in quarterly installments, percentage	1.25%
Term B Loan Facility | Bank of America, N.A.
Line of Credit Facility [Line Items]
Aggregate principal amount	$ 720,000,000
Debt agreement term	7 years
Obligated to repay outstanding principal in quarterly installments, percentage	0.25%
Revolving Credit Facility | Bank of America, N.A.
Line of Credit Facility [Line Items]
Aggregate principal amount	$ 450,000,000
Debt agreement term	5 years
New Senior Credit Facilities
Line of Credit Facility [Line Items]
Debt issuance costs incurred			69,800,000
Debt issuance costs capitalized			65,800,000
Debt extinguishment costs			4,000,000.0
Debt issuance expense			5,900,000
Unamortized discount amount			$ 59,800,000
New Senior Credit Facilities | Fifth Fiscal Quarter Through Eighth Fiscal Quarter After Closing Date
Line of Credit Facility [Line Items]
Leverage ratio	4.50
New Senior Credit Facilities | Subsequent Fiscal Quarter
Line of Credit Facility [Line Items]
Leverage ratio	4.00
New Senior Credit Facilities | Minimum
Line of Credit Facility [Line Items]
Interest coverage ratio	3.00
Amortization period			5 years
New Senior Credit Facilities | Maximum
Line of Credit Facility [Line Items]
Amortization period			7 years
New Senior Credit Facilities | Maximum | First Four Fiscal Quarters After Closing Date
Line of Credit Facility [Line Items]
Leverage ratio	5.00
New Senior Credit Facilities | Federal Funds Rate
Line of Credit Facility [Line Items]
Debt instrument, rate added on variable rate	0.50%
New Senior Credit Facilities | Eurodollar
Line of Credit Facility [Line Items]
Debt instrument, rate added on variable rate	1.00%
New Senior Credit Facilities | 0.25% Convertible Senior Note Due 2022 | I I V I Notes
Line of Credit Facility [Line Items]
Number of days prior to maturity of outstanding | d	120
Debt instrument, interest rate	0.25%