Retirement Benefit Plans - Benefit Obligation Assumptions (Details)	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Discount rate	1.70%	2.20%	2.40%
Rate of compensation increase	2.60%	2.60%	1.20%

Expected rate of compensation increases (for pay-related plans).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(2)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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