Business and Summary of Significant Accounting Policies - Impairments of Long-lived Assets (Details) - USD ($) $ in Millions	12 Months Ended
Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Accounting Policies [Abstract]
Impairment of long-lived assets	$ 0.0	$ 0.0	$ 0.0

The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Name:	us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration