Business Segments and Geographic Information - Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Sep. 29, 2018	Sep. 30, 2017	Sep. 24, 2016
Segment Reporting Information [Line Items]
Total revenue	$ 813.5	$ 824.0	$ 789.3	$ 791.1	$ 0.8	$ 0.8	$ 0.7	$ 0.7	$ 3,217.9	$ 3,058.8	$ 2,832.7
Operating income									(237.9)	1,370.2	548.6
Depreciation and amortization									480.3	449.2	465.4
Capital expenditures									105.6	107.6	94.5
Identifiable assets	7,230.9				7,979.6				7,230.9	7,979.6	7,317.0
Corporate
Segment Reporting Information [Line Items]
Capital expenditures									7.3	21.0	12.3
Identifiable assets	1,457.1				1,262.7				1,457.1	1,262.7	1,134.4
Diagnostics
Segment Reporting Information [Line Items]
Total revenue									1,147.4	1,197.1	1,236.9
Operating income									145.5	1,054.2	126.0
Depreciation and amortization									257.3	278.9	341.8
Capital expenditures									57.7	50.9	53.5
Identifiable assets	2,442.9				2,621.6				2,442.9	2,621.6	3,771.9
Breast Health
Segment Reporting Information [Line Items]
Total revenue									1,218.2	1,138.3	1,112.8
Operating income									399.7	373.4	350.5
Depreciation and amortization									22.7	19.7	22.6
Capital expenditures									14.8	12.0	10.6
Identifiable assets	972.4				824.0				972.4	824.0	809.1
Medical Aesthetics
Segment Reporting Information [Line Items]
Total revenue									339.1	207.5	0.0
Operating income									(844.7)	(115.9)	0.0
Depreciation and amortization									108.1	54.2	0.0
Capital expenditures									9.4	7.3	0.0
Identifiable assets	913.3				1,751.2				913.3	1,751.2	0.0
GYN Surgical
Segment Reporting Information [Line Items]
Total revenue									422.0	427.1	393.1
Operating income									58.3	65.0	69.1
Depreciation and amortization									91.6	95.7	99.9
Capital expenditures									13.1	15.2	17.7
Identifiable assets	1,414.9				1,494.6				1,414.9	1,494.6	1,570.7
Skeletal Health
Segment Reporting Information [Line Items]
Total revenue									91.2	88.8	89.9
Operating income									3.3	(6.5)	3.0
Depreciation and amortization									0.6	0.7	1.1
Capital expenditures									3.3	1.2	0.4
Identifiable assets	$ 30.3				$ 25.5				$ 30.3	$ 25.5	$ 30.9