Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation and Cash-Based Incentive Compensation - Outstanding Restricted Shares Issued to Non-employee Directors (Details)

v2.4.1.9
Share-Based Compensation and Cash-Based Incentive Compensation - Outstanding Restricted Shares Issued to Non-employee Directors (Details) (Restricted Shares)
Mar. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]  
Awards expected to vest by period 43,210us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
2015  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]  
Awards expected to vest by period 21,520us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_VestingAxis
= wti_TwoThousandFifteenMember
2016  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]  
Awards expected to vest by period 15,420us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_VestingAxis
= wti_TwoThousandSixteenMember
2017  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]  
Awards expected to vest by period 6,270us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_VestingAxis
= wti_TwoThousandAndSeventeenMember