Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Dec. 26, 2015	Dec. 27, 2014	Dec. 26, 2015	Dec. 27, 2014
Numerator:
Net income (loss)		$ 2.8	$ (4.1)	$ 2.6	$ 0.2
Less: Dividends on Series A preferred stock		(0.2)	0.0	(0.3)	0.0
Less: Accretion of Series A Preferred Stock		(2.0)	0.0	(11.7)	0.0
Net income (loss) available to common shareholders		$ 0.6	$ (4.1)	$ (9.4)	$ 0.2
Denominator:
Weighted-average number of common shares outstanding - basic (in shares)	[1]	59.0	58.8	58.9	58.8
Effect of dilutive securities from stock-based benefit plans (in shares)		0.2	0.0	0.0	0.0
Weighted-average number of common shares outstanding - diluted (in shares)	[1]	59.2	58.8	58.9	58.8
Net income (loss) per share attributable to common stockholders:
Basic (usd per share)	[1]	$ 0.01	$ (0.07)	$ (0.16)	$ 0.00
Diluted (usd per share)	[1]	$ 0.01	$ (0.07)	$ (0.16)	$ 0.00

[1] On August 1, 2015, JDS Uniphase Corporation (“JDSU”) distributed 47.1 million shares, or 80.1% of the outstanding shares of common stock of Lumentum Holdings Inc. (“we”, “our”, “Company” or “Lumentum”) to existing holders of JDSU common stock. JDSU was renamed Viavi Solutions Inc. (“Viavi”) and at the time of the distribution, retained 11.7 million shares, or 19.9% of Lumentum’s outstanding shares. Basic and diluted net income (loss) per share for the three and six months ended December 27, 2014 is calculated using the shares of Lumentum common stock outstanding on August 1, 2015, as if such shares were outstanding for the entire period.