Cash Equivalents and Investments - Narrative (Details) - USD ($)			3 Months Ended	9 Months Ended
Oct. 31, 2020	Jan. 31, 2020	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Contractual maturities of available-for-sale debt securities, maximum	36 months	36 months
Impairment of available-for-sale marketable debt securities, other-than-temporary			$ 0	$ 0	$ 0	$ 0
Marketable equity securities	$ 0		$ 0	$ 0	$ 0	$ 0

Amount of other-than-temporary impairment (OTTI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), recognized in earnings and other comprehensive loss (OCI).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=121553693&loc=SL6284422-111562

Name:	us-gaap_OtherThanTemporaryImpairmentLossDebtSecuritiesAvailableForSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration