Allowance for Doubtful Accounts (Narrative) (Details) $ in Thousands	3 Months Ended
Apr. 30, 2020 USD ($)
Increase in allowance for doubtful accounts	$ 9,737

Amount of increase (decrease) in allowance for credit loss on accounts receivable.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447

Name:	us-gaap_AllowanceForDoubtfulAccountsReceivablePeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration