Note 3 - Fair Value Measurement (Details Textual) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Securities for Reverse Repurchase Agreements, Unrealized Gain (Loss)	$ 0	$ 0

The amount of unrealized gain (loss) from securities for reverse repurchase agreements.

No definition available.

Name:	oxfd_SecuritiesForReverseRepurchaseAgreementsUnrealizedGainLoss
Namespace Prefix:	oxfd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration