Business Segments and Geographic Information - Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Sep. 28, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 850.5	$ 830.7
Income (loss) from operations	124.8	140.5
Depreciation and amortization	94.4	118.8
Capital expenditures	31.5	22.6
Identifiable assets	6,311.9		$ 6,442.1
Diagnostics
Segment Reporting Information [Line Items]
Total revenues	311.5	296.6
Income (loss) from operations	49.5	43.3
Depreciation and amortization	59.1	61.8
Capital expenditures	18.1	14.4
Identifiable assets	2,232.9		2,276.6
Breast Health
Segment Reporting Information [Line Items]
Total revenues	331.1	324.7
Income (loss) from operations	93.9	97.8
Depreciation and amortization	10.0	9.3
Capital expenditures	6.4	2.1
Identifiable assets	1,199.3		1,127.8
Medical Aesthetics
Segment Reporting Information [Line Items]
Total revenues	65.3	79.8
Income (loss) from operations	(51.0)	(25.2)
Depreciation and amortization	4.1	25.5
Capital expenditures	1.4	1.1
Identifiable assets	132.7		159.3
GYN Surgical
Segment Reporting Information [Line Items]
Total revenues	119.1	108.4
Income (loss) from operations	31.5	27.0
Depreciation and amortization	21.0	22.0
Capital expenditures	5.3	3.5
Identifiable assets	1,303.4		1,328.6
Skeletal Health
Segment Reporting Information [Line Items]
Total revenues	23.5	21.2
Income (loss) from operations	0.9	(2.4)
Depreciation and amortization	0.2	0.2
Capital expenditures	0.1	0.3
Identifiable assets	31.7		27.3
Corporate
Segment Reporting Information [Line Items]
Capital expenditures	0.2	$ 1.2
Identifiable assets	$ 1,411.9		$ 1,522.5