Income Taxes - Unrecognized Tax Benefits (Details) $ in Millions	Sep. 30, 2017 USD ($)
Income Taxes
Unrecognized tax benefits, if recognized, would affect effective tax rate	$ 31.2
Accrued gross interest and penalties	$ 0.5

Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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