Operating Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Dec. 27, 2014	Sep. 27, 2014 item	Dec. 28, 2013	Dec. 27, 2014	Dec. 28, 2013
Net revenue:
Net Revenue	$ 437.1		$ 447.6	$ 870.7	$ 876.6
Total net revenue	437.1us-gaap_SalesRevenueNet		447.6us-gaap_SalesRevenueNet	870.7us-gaap_SalesRevenueNet	876.6us-gaap_SalesRevenueNet
Operating income (loss):
Total operating income	43.1jdsu_SegmentOperatingIncomeLoss		49.2jdsu_SegmentOperatingIncomeLoss	82.6jdsu_SegmentOperatingIncomeLoss	84.6jdsu_SegmentOperatingIncomeLoss
Unallocated amounts:
Restructuring and related charges	(9.7)us-gaap_BusinessExitCosts1		(1.0)us-gaap_BusinessExitCosts1	(12.6)us-gaap_BusinessExitCosts1	(0.2)us-gaap_BusinessExitCosts1
Interest and other income (expense), net	0.4us-gaap_OtherNonoperatingIncomeExpense		0.4us-gaap_OtherNonoperatingIncomeExpense	0.9us-gaap_OtherNonoperatingIncomeExpense	(0.2)us-gaap_OtherNonoperatingIncomeExpense
Interest expense	(8.5)us-gaap_InterestExpense		(8.4)us-gaap_InterestExpense	(16.8)us-gaap_InterestExpense	(13.6)us-gaap_InterestExpense
(Loss) income before income taxes	(16.3)		11.8	(19.9)	12.6
Realignment and other charges	16.3jdsu_RealignmentAndOtherCharges			16.7jdsu_RealignmentAndOtherCharges
Number of reporting units		2us-gaap_NumberOfReportableSegments
Corporate
Operating income (loss):
Total operating income	(22.3)		(23.9)	(44.7)	(47.4)
Segment Reconciling Items
Unallocated amounts:
Stock-based compensation	(15.0)		(15.7)	(30.7)	(31.4)
Amortization of intangibles	(16.1)		(12.7)	(31.2)	(26.8)
Loss (gain) on disposal of long-lived assets			0.5		0.2
Restructuring and related charges	(9.7)		(1.0)	(12.6)	(0.2)
Other charges related to non-recurring activities	(10.5)		(0.5)	(12.1)
Interest and other income (expense), net	0.4		0.4	0.9	(0.2)
Interest expense	(8.5)		(8.4)	(16.8)	(13.6)
(Loss) income before income taxes	(16.3)		11.8	(19.9)	12.6
Network Enablement
Net revenue:
Net Revenue	133.7		155.8	266.5	300.9
Operating income (loss):
Total operating income	22.5		30.9	42.6	53.4
Service Enablement
Net revenue:
Net Revenue	45.7		39.2	93.9	66.0
Operating income (loss):
Total operating income	(2.5)		(2.2)	(1.7)	(12.1)
Communications and Commercial Optical Products
Net revenue:
Net Revenue	207.1		198.0	416.4	402.6
Operating income (loss):
Total operating income	26.6		23.9	51.7	51.1
Optical Security and Performance Products
Net revenue:
Net Revenue	50.6		54.6	93.9	107.1
Operating income (loss):
Total operating income	$ 18.8		$ 20.5	$ 34.7	$ 39.6

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