Note 1 - Business and Basis of Presentation (Details Textual)	Sep. 30, 2020
US Treasury Securities [Member]
Cash Equivalents, US Treasury Securities Collateral for Reverse Repurchase Agreements, Percent of Principal	102.00%

The percent of principal for cash equivalents of US Treasury securities collateral for reverse repurchase agreements.

No definition available.

Name:	oxfd_CashEquivalentsUsTreasurySecuritiesCollateralForReverseRepurchaseAgreementsPercentOfPrincipal
Namespace Prefix:	oxfd_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant