Goodwill and Intangibles, net - Summary of Changes in Carrying Amounts of Goodwill and Intangible Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Goodwill And Intangible Assets [Line Items]
Goodwill, Purchase Accounting Adjustments	$ 0.0
Deconsolidation, Gain (Loss), Amount	0.0	$ 0.0	$ 38.5
Cost	1,423.9	1,387.7
Intangible Assets, Including Goodwill [Roll Forward]
Beginning Balance, Goodwill	2,478.4	2,487.4
Beginning Balance, Indefinite Lived Intangible Assets	1,473.5	1,490.3
Beginning Balance, Finite Lived Intangible Assets	899.0
Beginning Balance, Intangible Assets, Excluding Goodwill	2,372.5	2,480.3
Goodwill, Acquired During Period		3.3
Indefinite-lived Intangible Assets Acquired		1.0
Acquisitions (Note 13)		4.2
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)			(31.9)
Impairment of Intangible Assets, Finite-lived	(16.3)	(15.4)	(60.2)
Impairment of Intangible Assets (Excluding Goodwill)	(16.3)	(4.7)
Indefinite-lived Intangible Assets, Written off Related to Sale of Business Unit		(9.9)
Less: Components of amortization:
Effect of translation, Goodwill	12.6	(1.6)
Effect of translation, Indefinite Lived intangible assets		(13.1)
Effect of translation, Finite Lived intangible assets	15.7	(13.4)
Ending Balance, Goodwill	2,626.0	2,478.4	2,487.4
Ending Balance, Indefinite Lived Intangible Assets	1,548.8	1,473.5	1,490.3
Ending Balance, Finite Lived Intangible Assets	875.2	899.0
Ending Balance, Intangible Assets, Excluding Goodwill	2,424.0	2,372.5	2,480.3
Finite-Lived Intangible Assets, Accumulated Amortization	548.7	488.7
Finite-Lived Intangible Assets, Period Increase (Decrease)		(0.9)
Intangible Assets, Purchase Accounting Adjustments	148.2
Periodic amortization
Less: Components of amortization:
Amortization of Intangible Assets	(95.2)	(93.9)
Customer Relationships [Member]
Goodwill And Intangible Assets [Line Items]
Cost	1,007.6	984.8
Intangible Assets, Including Goodwill [Roll Forward]
Beginning Balance, Finite Lived Intangible Assets	681.9
Less: Components of amortization:
Amortization of Intangible Assets			(87.8)
Ending Balance, Finite Lived Intangible Assets	646.9	681.9
Finite-Lived Intangible Assets, Accumulated Amortization	360.7	302.9
Definite Lived Intangible Assets
Intangible Assets, Including Goodwill [Roll Forward]
Beginning Balance, Finite Lived Intangible Assets	899.0	990.0
Acquisitions (Note 3), Finite-Lived Intangible Assets		3.2
Impairment of Intangible Assets, Finite-lived	0.0	0.0
Less: Components of amortization:
Amortization of Intangible Assets	(95.2)	(93.9)
Effect of translation, Finite Lived intangible assets	5.2	(0.3)
Ending Balance, Finite Lived Intangible Assets	875.2	899.0	990.0
Finite-Lived Intangible Assets, Purchase Accounting Adjustments	67.1	(0.9)
Definite Lived Intangible Assets | Periodic amortization
Less: Components of amortization:
Amortization of Intangible Assets	(95.2)	(93.9)
Goodwill [Member]
Less: Components of amortization:
Amortization of Intangible Assets		0.0
Trade Names [Member]
Goodwill And Intangible Assets [Line Items]
Cost	165.8	165.7
Intangible Assets, Including Goodwill [Roll Forward]
Beginning Balance, Finite Lived Intangible Assets	76.6
Less: Components of amortization:
Ending Balance, Finite Lived Intangible Assets	61.2	76.6
Finite-Lived Intangible Assets, Accumulated Amortization	104.6	89.1
CorAmerica [Member]
Intangible Assets, Including Goodwill [Roll Forward]
Goodwill and Intangible Asset Impairment		(10.7)	$ (28.3)
Spectrum Brands [Member]
Intangible Assets, Including Goodwill [Roll Forward]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	(16.3)	$ (4.7)
Indefinite Lived Intangible Assets Excluding Goodwill [Member]
Less: Components of amortization:
Effect of translation, Indefinite Lived intangible assets	10.5
Indefinite-lived Intangible Assets, Purchase Accounting Adjustments	$ 81.1