Business Segments and Geographic Information - Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2018	Apr. 01, 2017	Mar. 31, 2018	Apr. 01, 2017	Sep. 30, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 789.3	$ 715.4	$ 1,580.4	$ 1,449.8
Operating income (loss)	(604.2)	999.8	(470.1)	1,145.8
Depreciation and amortization	119.5	95.1	240.7	210.4
Capital expenditures	27.0	25.1	48.8	49.8
Identifiable assets	7,234.4		7,234.4		$ 7,979.6
Diagnostics
Segment Reporting Information [Line Items]
Total revenues	279.7	296.0	564.3	621.3
Operating income (loss)	34.2	929.7	70.7	970.9
Depreciation and amortization	64.1	64.4	128.8	149.3
Capital expenditures	14.0	11.5	25.9	21.8
Identifiable assets	2,548.2		2,548.2		2,621.6
Breast Health
Segment Reporting Information [Line Items]
Total revenues	300.1	280.5	588.1	553.8
Operating income (loss)	101.5	92.7	191.2	177.9
Depreciation and amortization	5.5	4.6	10.4	9.7
Capital expenditures	3.8	1.8	7.3	4.0
Identifiable assets	854.9		854.9		824.0
GYN Surgical
Segment Reporting Information [Line Items]
Total revenues	99.4	101.1	206.9	215.9
Operating income (loss)	17.9	1.8	48.2	27.2
Depreciation and amortization	22.8	23.4	45.7	48.5
Capital expenditures	3.3	3.3	5.7	7.4
Identifiable assets	1,457.7		1,457.7		1,494.6
Skeletal Health
Segment Reporting Information [Line Items]
Total revenues	24.6	21.8	44.3	42.8
Operating income (loss)	2.3	0.1	2.9	(5.7)
Depreciation and amortization	0.1	0.2	0.3	0.4
Capital expenditures	0.1	0.1	0.8	0.4
Identifiable assets	26.1		26.1		25.5
Medical Aesthetics
Segment Reporting Information [Line Items]
Total revenues	85.5	16.0	176.8	16.0
Operating income (loss)	(760.1)	(24.5)	(783.1)	(24.5)
Depreciation and amortization	27.0	2.5	55.5	2.5
Capital expenditures	3.5	0.4	5.1	0.4
Identifiable assets	967.2		967.2		1,751.2
Corporate
Segment Reporting Information [Line Items]
Capital expenditures	2.3	$ 8.0	4.0	$ 15.8
Identifiable assets	$ 1,380.3		$ 1,380.3		$ 1,262.7

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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