Description of Business and Summary of Significant Accounting Policies - Merger Agreement (Details)	3 Months Ended	9 Months Ended
	Sep. 29, 2018 USD ($)	Dec. 11, 2018 USD ($) $ / shares	Mar. 11, 2018 USD ($)
Term Loan Credit Facility
Business Acquisition [Line Items]
Senior secured term loan facility	$ 500,000,000
Ticking fee expense	400,000
Debt issuance costs capitalized	$ 900,000
Term Loan Credit Facility | 31st Day Following Allocation
Business Acquisition [Line Items]
Ticking fee	1.25%
Term Loan Credit Facility | 61st Day Following Allocation
Business Acquisition [Line Items]
Ticking fee	2.50%
Forecast | Oclaro, Inc.
Business Acquisition [Line Items]
Total transaction consideration as of date of the Merger Agreement		$ 1,800,000,000
Percentage of interest owned by Oclaro shareholders of combined company		16.00%
Oclaro, Inc.
Business Acquisition [Line Items]
Maximum borrowing capacity			$ 550,000,000
Oclaro, Inc. | Forecast
Business Acquisition [Line Items]
Exchange for consideration, cash paid for each share of Oclaro common stock (usd per share) | $ / shares		$ 5.60
Exchange for consideration, shares paid paid for each share of Oclaro common stock		0.0636
Termination fee if terms of Merger Agreement not met		$ 80,000,000
Total transaction consideration		1,600,000,000
Lumentum common stock		600,000,000
New debt incurred in total transaction consideration		$ 500,000,000