Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jun. 30, 2019
Income Tax Contingency [Line Items]
Effective income tax rate (benefit) expense, percent	(13.00%)	15.50%
U.S. statutory rate	21.00%
Unrecognized tax benefits	$ 74.5		$ 11.5
Unrecognized tax benefits that would impact effective tax rate	70.8
Interest and penalties accrued	15.8		$ 1.2
Finisar Corporation
Income Tax Contingency [Line Items]
Unrecognized tax benefits	64.0
Liability for uncertainty in income taxes, current	18.8
Liability for uncertain tax positions, noncurrent	$ 55.7