Related Parties-Sponsor, Trustee, Custodian and Marketing Fees (Details)	12 Months Ended
Jan. 31, 2020 USD ($)
Related Parties-Sponsor, Trustee, Custodian and Marketing Fees (Textual)
Percentage of sponsor's fee	0.40%
Legal expenses, per annum	$ 100,000

The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

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