Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2019
Income Tax Contingency [Line Items]
U.S. statutory rate	21.00%
Effective income tax rate (benefit) expense	(10.00%)	18.20%
Unrecognized tax benefits that would impact effective tax rate	$ 74.0		$ 11.5
Interest and penalties accrued	15.6		$ 1.2
Liability for uncertain tax positions	70.3
Finisar Corporation
Income Tax Contingency [Line Items]
Liability for uncertain tax positions	$ 64.0
United States Internal Revenue Service | Earliest Tax Year
Income Tax Contingency [Line Items]
Tax year remain open to examination	2017
United States Internal Revenue Service | Latest Tax Year
Income Tax Contingency [Line Items]
Tax year remain open to examination	2020
State Jurisdictions | Earliest Tax Year
Income Tax Contingency [Line Items]
Tax year remain open to examination	2015
State Jurisdictions | Latest Tax Year
Income Tax Contingency [Line Items]
Tax year remain open to examination	2020
Foreign Taxing Jurisdictions | Earliest Tax Year
Income Tax Contingency [Line Items]
Tax year remain open to examination	2009
Foreign Taxing Jurisdictions | Latest Tax Year
Income Tax Contingency [Line Items]
Tax year remain open to examination	2020
Subsidiaries in Philippines
Income Tax Contingency [Line Items]
Income tax examination, year(s) under examination	2017
Subsidiary in Germany | Earliest Tax Year
Income Tax Contingency [Line Items]
Income tax examination, year(s) under examination	2012
Subsidiary in Germany | Latest Tax Year
Income Tax Contingency [Line Items]
Income tax examination, year(s) under examination	2015
Subsidiary in Florida | Earliest Tax Year
Income Tax Contingency [Line Items]
Income tax examination, year(s) under examination	2016
Subsidiary in Florida | Latest Tax Year
Income Tax Contingency [Line Items]
Income tax examination, year(s) under examination	2018
Subsidiary in Vietnam | Earliest Tax Year
Income Tax Contingency [Line Items]
Income tax examination, year(s) under examination	2018
Subsidiary in Vietnam | Latest Tax Year
Income Tax Contingency [Line Items]
Income tax examination, year(s) under examination	2019
Subsidiary in Australia | Earliest Tax Year
Income Tax Contingency [Line Items]
Income tax examination, year(s) under examination	2011
Subsidiary in Australia | Latest Tax Year
Income Tax Contingency [Line Items]
Income tax examination, year(s) under examination	2014
Subsidiary in India
Income Tax Contingency [Line Items]
Income tax examination, year(s) under examination	2016