Supplemental Balance Sheet Information - Goodwill (Details) - USD ($) $ in Millions		9 Months Ended
Oct. 31, 2015	Jul. 31, 2016
Goodwill [Roll Forward]
Goodwill, beginning of period		$ 284.4
Measurement period adjustment		(2.9)
Foreign currency translation adjustments		0.3
Goodwill, end of period	$ 284.4	281.8
BLS \| Spinoff
Goodwill [Roll Forward]
Spinoff impact	11.1
Banner Puerto Rico
Goodwill [Roll Forward]
Impairment loss	172.5
Banner Canada
Goodwill [Roll Forward]
Goodwill, end of period		$ 2.7
Banner Canada \| Banner Pharmacaps
Goodwill [Roll Forward]
Impairment loss	0.1
Banner Canada \| Biosolutions
Goodwill [Roll Forward]
Impairment loss	1.3
Banner Mexico \| Banner Pharmacaps
Goodwill [Roll Forward]
Disposition impact	$ 3.1

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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