Summary of Significant Accounting Policies - Goodwill and Other Intangible Assets (Details) - Goodwill and Indefinite-lived Intangible Assets - Income Approach Valuation Technique	12 Months Ended
Sep. 30, 2017
Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rates used for reporting unit valuations	9.00%
Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rates used for reporting unit valuations	12.00%

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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Period Type:	duration