Supplemental Guarantor Condensed Consolidating Financials - Schedule of Supplemental Condensed Consolidating Statement of Operations (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 27, 2015	Jun. 28, 2014	Jun. 27, 2015	Jun. 28, 2014
Revenues:
Product	$ 583.0	$ 529.3	$ 1,676.0	$ 1,562.8
Service and other	110.9	103.3	326.2	307.3
Revenues	693.9	632.6	2,002.2	1,870.1
Costs of revenues:
Product	186.2	186.7	559.6	549.3
Amortization of intangible assets	73.1	80.5	225.6	234.1
Impairment of intangible assets	0.0	0.0	0.0	26.6
Service and other	55.9	52.6	163.7	159.6
Gross Profit	378.7	312.8	1,053.3	900.5
Operating expenses:
Research and development	56.0	52.5	161.2	151.1
Selling and marketing	94.3	83.0	263.3	245.0
General and administrative	73.1	64.7	194.7	194.6
Amortization of intangible assets	27.4	29.7	82.8	85.0
Impairment of intangible assets	0.0	0.0	0.0	0.5
Restructuring and divestiture charges	11.9	6.7	21.9	36.6
Operating expenses	262.7	236.6	723.9	712.8
Income from operations	116.0	76.2	329.4	187.7
Interest income	0.3	0.3	1.0	0.8
Interest expense	(52.4)	(52.4)	(154.3)	(168.1)
Debt extinguishment loss	(18.2)	0.0	(24.9)	(7.4)
Other income (expense), net	1.0	(1.5)	0.6	(3.5)
Income before income taxes	46.7	22.6	151.8	9.5
Provision for income taxes	17.3	11.3	45.3	20.3
Equity in earnings (losses) of subsidiaries	0.0	0.0	0.0	0.0
Net income (loss)	29.4	11.3	106.5	(10.8)
Eliminations
Revenues:
Product	(154.0)	(111.3)	(423.3)	(321.7)
Service and other	(6.9)	(12.4)	(29.9)	(40.0)
Revenues	(160.9)	(123.7)	(453.2)	(361.7)
Costs of revenues:
Product	(154.0)	(111.3)	(423.3)	(321.7)
Amortization of intangible assets	0.0	0.0	0.0	0.0
Impairment of intangible assets				0.0
Service and other	(6.9)	(12.4)	(29.9)	(40.0)
Gross Profit	0.0	0.0	0.0	0.0
Operating expenses:
Research and development	0.0	0.0	0.0	0.0
Selling and marketing	0.0	0.0	0.0	0.0
General and administrative	0.0	0.0	0.0	0.0
Amortization of intangible assets	0.0	0.0	0.0	0.0
Impairment of intangible assets				0.0
Restructuring and divestiture charges	0.0	0.0	0.0	0.0
Operating expenses	0.0	0.0	0.0	0.0
Income from operations	0.0	0.0	0.0	0.0
Interest income	0.0	(1.1)	(1.3)	(2.5)
Interest expense	0.0	1.1	1.4	2.5
Debt extinguishment loss	0.0		0.0	0.0
Other income (expense), net	(0.1)	0.0	(0.4)	0.0
Income before income taxes	(0.1)	0.0	(0.3)	0.0
Provision for income taxes	0.0	0.0	0.0	0.0
Equity in earnings (losses) of subsidiaries	(39.1)	(7.6)	140.5	(4.2)
Net income (loss)	(39.2)	(7.6)	140.2	(4.2)
Parent/Issuer
Revenues:
Product	172.2	128.4	438.3	356.8
Service and other	94.6	88.2	278.1	262.7
Revenues	266.8	216.6	716.4	619.5
Costs of revenues:
Product	84.0	61.5	217.9	172.4
Amortization of intangible assets	0.8	1.4	3.6	4.2
Impairment of intangible assets				0.0
Service and other	46.4	46.8	130.9	140.3
Gross Profit	135.6	106.9	364.0	302.6
Operating expenses:
Research and development	10.2	7.7	28.2	23.0
Selling and marketing	26.8	16.8	74.3	52.6
General and administrative	21.5	15.8	56.3	45.5
Amortization of intangible assets	0.2	0.6	1.1	2.4
Impairment of intangible assets				0.0
Restructuring and divestiture charges	10.1	1.0	11.5	7.6
Operating expenses	68.8	41.9	171.4	131.1
Income from operations	66.8	65.0	192.6	171.5
Interest income	0.2	0.1	0.6	0.3
Interest expense	(51.8)	(52.6)	(152.2)	(168.0)
Debt extinguishment loss	(18.2)		(24.9)	(7.4)
Other income (expense), net	1.1	1.3	251.6	7.9
Income before income taxes	(1.9)	13.8	267.7	4.3
Provision for income taxes	4.3	6.8	14.3	5.0
Equity in earnings (losses) of subsidiaries	35.6	4.3	(146.9)	(10.1)
Net income (loss)	29.4	11.3	106.5	(10.8)
Guarantor Subsidiaries
Revenues:
Product	448.6	386.4	1,312.1	1,154.0
Service and other	10.0	14.4	39.9	47.4
Revenues	458.6	400.8	1,352.0	1,201.4
Costs of revenues:
Product	171.0	147.3	515.2	431.7
Amortization of intangible assets	72.2	75.3	221.8	224.0
Impairment of intangible assets				0.0
Service and other	8.1	5.9	38.7	27.5
Gross Profit	207.3	172.3	576.3	518.2
Operating expenses:
Research and development	44.0	42.9	127.8	121.7
Selling and marketing	50.0	43.4	132.5	126.8
General and administrative	43.2	37.8	113.8	114.9
Amortization of intangible assets	26.2	26.8	78.5	77.9
Impairment of intangible assets				0.0
Restructuring and divestiture charges	0.0	2.9	0.6	15.0
Operating expenses	163.4	153.8	453.2	456.3
Income from operations	43.9	18.5	123.1	61.9
Interest income	0.0	1.1	1.2	2.3
Interest expense	(0.3)	(0.3)	(2.0)	(0.8)
Debt extinguishment loss	0.0		0.0	0.0
Other income (expense), net	0.3	(3.0)	(251.1)	(12.4)
Income before income taxes	43.9	16.3	(128.8)	51.0
Provision for income taxes	12.3	3.6	28.0	9.9
Equity in earnings (losses) of subsidiaries	3.5	3.3	6.4	14.3
Net income (loss)	35.1	16.0	(150.4)	55.4
Non-Guarantor Subsidiaries
Revenues:
Product	116.2	125.8	348.9	373.7
Service and other	13.2	13.1	38.1	37.2
Revenues	129.4	138.9	387.0	410.9
Costs of revenues:
Product	85.2	89.2	249.8	266.9
Amortization of intangible assets	0.1	3.8	0.2	5.9
Impairment of intangible assets				26.6
Service and other	8.3	12.3	24.0	31.8
Gross Profit	35.8	33.6	113.0	79.7
Operating expenses:
Research and development	1.8	1.9	5.2	6.4
Selling and marketing	17.5	22.8	56.5	65.6
General and administrative	8.4	11.1	24.6	34.2
Amortization of intangible assets	1.0	2.3	3.2	4.7
Impairment of intangible assets				0.5
Restructuring and divestiture charges	1.8	2.8	9.8	14.0
Operating expenses	30.5	40.9	99.3	125.4
Income from operations	5.3	(7.3)	13.7	(45.7)
Interest income	0.1	0.2	0.5	0.7
Interest expense	(0.3)	(0.6)	(1.5)	(1.8)
Debt extinguishment loss	0.0		0.0	0.0
Other income (expense), net	(0.3)	0.2	0.5	1.0
Income before income taxes	4.8	(7.5)	13.2	(45.8)
Provision for income taxes	0.7	0.9	3.0	5.4
Equity in earnings (losses) of subsidiaries	0.0	0.0	0.0	0.0
Net income (loss)	$ 4.1	$ (8.4)	$ 10.2	$ (51.2)