Note 6 - Derivative Financial Instruments - Cash Receipts on Commodity Derivative Contract Settlements (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018
Cash receipts (payments) on derivative settlements, net	$ 17,583	$ (3,091)

The cash inflow (outflow) from derivative instruments during the period, which are classified as operating activities, excluding those designated as hedging instruments.

No definition available.

Name:	wti_ProceedsFromPaymentsForDerivativeInstrumentOperatingActivities
Namespace Prefix:	wti_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration