Business Segments and Geographic Information - Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Sep. 26, 2020
Segment Reporting Information [Line Items]
Total revenues	$ 1,609.8	$ 850.5
Income (loss) from operations	885.5	124.8
Depreciation and amortization	92.8	94.4
Capital expenditures	44.8	31.5
Identifiable assets	7,550.7		$ 7,195.8
Diagnostics
Segment Reporting Information [Line Items]
Total revenues	1,128.2	311.5
Income (loss) from operations	784.5	49.5
Depreciation and amortization	56.3	59.1
Capital expenditures	38.3	18.1
Identifiable assets	2,177.8		2,161.4
Breast Health
Segment Reporting Information [Line Items]
Total revenues	332.7	331.1
Income (loss) from operations	86.3	93.9
Depreciation and amortization	13.1	10.0
Capital expenditures	2.9	6.4
Identifiable assets	1,203.4		1,200.9
Medical Aesthetics
Segment Reporting Information [Line Items]
Total revenues	0.0	65.3
Income (loss) from operations	0.0	(51.0)
Depreciation and amortization	0.0	4.1
Capital expenditures	0.0	1.4
GYN Surgical
Segment Reporting Information [Line Items]
Total revenues	124.0	119.1
Income (loss) from operations	13.7	31.5
Depreciation and amortization	23.2	21.0
Capital expenditures	3.3	5.3
Identifiable assets	1,418.5		1,438.7
Skeletal Health
Segment Reporting Information [Line Items]
Total revenues	24.9	23.5
Income (loss) from operations	1.0	0.9
Depreciation and amortization	0.2	0.2
Capital expenditures	0.0	0.1
Identifiable assets	31.3		38.9
Corporate
Segment Reporting Information [Line Items]
Capital expenditures	0.3	$ 0.2
Identifiable assets	$ 2,719.7		$ 2,355.9