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Business Segments and Geographic Information - Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018
Segment Reporting Information [Line Items]
Total revenue	$ 1,347.0	$ 822.9	$ 756.1	$ 850.5	$ 865.8	$ 852.4	$ 818.4	$ 830.7	$ 3,776.4	$ 3,367.3	$ 3,217.9
Operating income									1,105.0	(123.8)	(237.9)
Depreciation and amortization									376.0	463.1	480.3
Capital expenditures									156.4	109.1	105.6
Identifiable assets	7,195.8				6,442.1				7,195.8	6,442.1	7,230.9
Corporate
Segment Reporting Information [Line Items]
Capital expenditures									3.8	7.7	7.3
Identifiable assets	2,355.9				1,522.5				2,355.9	1,522.5	1,457.1
Diagnostics
Segment Reporting Information [Line Items]
Total revenue									2,102.1	1,205.5	1,147.4
Operating income									929.7	163.1	145.5
Depreciation and amortization									237.3	246.6	257.3
Capital expenditures									110.7	59.2	57.7
Identifiable assets	2,161.4				2,276.6				2,161.4	2,276.6	2,442.9
Breast Health
Segment Reporting Information [Line Items]
Total revenue									1,151.9	1,314.2	1,218.2
Operating income									192.8	399.3	399.7
Depreciation and amortization									48.8	36.8	22.7
Capital expenditures									22.4	18.3	14.8
Identifiable assets	1,200.9				1,127.8				1,200.9	1,127.8	972.4
Medical Aesthetics
Segment Reporting Information [Line Items]
Total revenue									65.3	315.6	339.1
Operating income									(57.1)	(781.2)	(844.7)
Depreciation and amortization									4.1	91.4	108.1
Capital expenditures									1.4	7.0	9.4
Identifiable assets	0.0				159.3				0.0	159.3	913.3
Skeletal Health
Segment Reporting Information [Line Items]
Total revenue									81.0	94.8	91.2
Operating income									(2.4)	(4.2)	3.3
Depreciation and amortization									0.7	0.6	0.6
Capital expenditures									0.2	1.2	3.3
Identifiable assets	38.9				27.3				38.9	27.3	30.3
Gyn Surgical [Member]
Segment Reporting Information [Line Items]
Total revenue									376.1	437.2	422.0
Operating income									42.0	99.2	58.3
Depreciation and amortization									85.1	87.7	91.6
Capital expenditures									17.9	15.7	13.1
Identifiable assets	$ 1,438.7				$ 1,328.6				$ 1,438.7	$ 1,328.6	$ 1,414.9