Segments - Revenue from External Customers by Products and Services (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Revenue from External Customer [Line Items]
Net sales	$ 359.0	$ 334.0	$ 918.6	$ 840.8
Batteries
Revenue from External Customer [Line Items]
Net sales	309.9	311.1	813.0	784.6
Other
Revenue from External Customer [Line Items]
Net sales	$ 49.1	$ 22.9	$ 105.6	$ 56.2

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Name:	us-gaap_SalesRevenueNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration