Business Segments and Geographic Information - Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 30, 2019	Mar. 31, 2018	Mar. 30, 2019	Mar. 31, 2018	Sep. 29, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 818.4	$ 789.3	$ 1,649.1	$ 1,580.4
Income (loss) from operations	(323.2)	(604.2)	(182.7)	(470.1)
Depreciation and amortization	117.6	119.5	236.4	240.7
Capital expenditures	29.3	27.0	51.9	48.8
Identifiable assets	6,525.3		6,525.3		$ 7,230.9
Diagnostics
Segment Reporting Information [Line Items]
Total revenues	296.7	279.7	593.3	564.3
Income (loss) from operations	31.1	34.2	74.4	70.7
Depreciation and amortization	61.6	64.1	123.4	128.8
Capital expenditures	16.0	14.0	30.4	25.9
Identifiable assets	2,364.4		2,364.4		2,442.9
Breast Health
Segment Reporting Information [Line Items]
Total revenues	321.5	300.1	646.2	588.1
Income (loss) from operations	99.0	101.5	196.8	191.2
Depreciation and amortization	8.9	5.5	18.2	10.4
Capital expenditures	4.7	3.8	6.8	7.3
Identifiable assets	1,131.3		1,131.3		972.4
Medical Aesthetics
Segment Reporting Information [Line Items]
Total revenues	73.8	85.5	153.6	176.8
Income (loss) from operations	(473.9)	(760.1)	(499.1)	(783.1)
Depreciation and amortization	25.1	27.0	50.6	55.5
Capital expenditures	3.4	3.5	4.5	5.1
Identifiable assets	432.0		432.0		913.3
GYN Surgical
Segment Reporting Information [Line Items]
Total revenues	102.2	99.4	210.6	206.9
Income (loss) from operations	20.5	17.9	47.6	48.2
Depreciation and amortization	21.9	22.8	43.9	45.7
Capital expenditures	3.1	3.3	6.6	5.7
Identifiable assets	1,373.7		1,373.7		1,414.9
Skeletal Health
Segment Reporting Information [Line Items]
Total revenues	24.2	24.6	45.4	44.3
Income (loss) from operations	0.1	2.3	(2.4)	2.9
Depreciation and amortization	0.1	0.1	0.3	0.3
Capital expenditures	0.3	0.1	0.6	0.8
Identifiable assets	32.7		32.7		30.3
Corporate
Segment Reporting Information [Line Items]
Capital expenditures	1.8	$ 2.3	3.0	$ 4.0
Identifiable assets	$ 1,191.2		$ 1,191.2		$ 1,457.1