b'commodity prices and interest rates. These disclosures are not meant to be precise indicators ofexpected future losses, but rather indicators of reasonably possible losses. This forward-lookinginformation provides indicators of how we view and manage ongoing market risk exposures. We enterinto market-risk sensitive instruments for purposes other than to speculate.We manage market and counterparty credit risk in accordance with our policies. In accordancewith these policies and guidelines, our management determines the appropriate timing and extent ofderivative transactions. See Item 8. Financial Statements and Supplementary DataNote 2Accounting Policies, Note 9Derivative Financial Instruments and Note 10Fair ValueMeasurements for a description of the accounting procedures we follow relative to our derivativefinancial instruments.The following table reconciles the changes that occurred in fair values of our open derivativecontracts during the year ended December 31, 2018:Derivative Contracts Assets (Liabilities)Commodities Interest Rates Total(In thousands)Fair value of contracts outstanding as ofDecember 31, 2017 . . . . . . . . . . . . . . . . . . . $(97,036) $ 1,017 $(96,019)Acquisition and novation of DGE contracts . . . (41,139)(41,139)Changes in contract fair value. . . . . . . . . . . . . 29,468 492 29,960Contract maturities . . . . . . . . . . . . . . . . . . . . 139,451 (1,509) 137,942Fair value of contracts outstanding as ofDecember 31, 2018 . . . . . . . . . . . . . . . . . . . $ 30,744 $$ 30,744Commodity Price RiskThe Companys revenues, earnings, cash flows, capital investments and, ultimately, future rate ofgrowth are highly dependent on the prices we receive for our crude oil, which have historically beenvery volatile. Substantially all of our oil sales are indexed against Dated Brent, Eugene Island, HeavyLouisiana Sweet and Mars crude.Commodity Derivative InstrumentsWe enter into various oil derivative contracts to mitigate our exposure to commodity price riskassociated with anticipated future oil production. These contracts currently consist of collars, putoptions, call options and swaps. In regards to our obligations under our various commodity derivativeinstruments, if our production does not exceed our existing hedged positions, our exposure to ourcommodity derivative instruments would increase.100'