Derivative Financial Instruments - Cash Payments on Derivative Settlements, Net Included within Net Cash Provided by Operating Activities (Details) $ in Thousands	6 Months Ended
Jun. 30, 2014 USD ($)
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Cash payments on derivative settlements, net	$ 14,310

Net cash payments or net cash received related to derivative settlements.

No definition available.

Name:	wti_CashPaymentsReceiptsOnDerivativeSettlements
Namespace Prefix:	wti_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration