Selected Quarterly Financial Data (Unaudited) - Footnote Disclosure (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Oct. 31, 2018	Jan. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Tax benefit, reduction resulting from enactment of the tax act		$ 22.6
One-time net tax act benefit related to Tax Act (usd per share)		$ 0.34
Goodwill and intangible asset impairment	$ 26.5
Goodwill and intangible asset impairment (usd per share)	$ 0.40

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228

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Period Type:	duration