Amount before allocation of valuation allowances of deferred tax asset attributable to deductible research tax credit carryforwards.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

INCOME TAXES - Research and Development Tax Credits (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2018	Apr. 30, 2021	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
INCOME TAXES
Prior period for identify and quantify the amounts of research and development credits	3 years
Research and development tax credit benefit				$ 0.4	$ 16.6
Unrecognized income tax benefits related to research and development credits		$ 5.0
Income tax refunds and prepaid income taxes			$ 26.9