Fair Value Measurements (Policies)

6 Months Ended

Jun. 30, 2011

Fair Value of Financial Instruments, Policy

We apply the authoritative accounting provisions for measuring fair value of both our financial and nonfinancial assets and liabilities.  Fair value is an exit price representing the expected amount we would receive to sell an asset or pay to transfer a liability in an orderly transaction with market participants at the measurement date.  We have followed consistent methods and assumptions to estimate the fair values as more fully described in our Annual Report on Form 10-K for the year ended December 31, 2010.

Our financial instruments that are subject to fair value disclosure consist of cash and cash equivalents, accounts receivable, accounts payable, derivatives and long-term debt. As of June 30, 2011, the carrying values of all of these financial instruments, except the portion of long-term debt with fixed interest rates, approximated fair value.

Fair Value, Measurements, Recurring

Fair Value of Financial Instruments, Policy

We used the following methods and assumptions to estimate fair values:

• Publicly traded equity securities: We hold various publicly traded equity securities as assets for funding certain deferred compensation obligations. The fair values are based on quoted market prices, which are level 1 inputs.

• Commodity derivatives: We determine the fair values of our oil and gas derivative instruments based on discounted cash flows derived from third-party quoted forward prices for NYMEX Henry Hub natural gas and West Texas Intermediate crude oil closing prices as of the end of the reporting periods.  We generally use the income approach, using valuation techniques that convert future cash flows to a single discounted value. Each of these is a level 2 input.

• Interest rate swaps: We determine the fair values of our interest rate swaps using an income approach valuation technique that connects future cash flows to a single discounted value. We estimate the fair value of the swaps based on published interest rate yield curves as of the date of the estimate. Each of these is a level 2 input.

• Deferred compensation: Certain of our deferred compensation obligations are ultimately to be settled in cash based on the underlying fair value of certain publicly traded equity securities. The fair values of these obligations are based on quoted market prices, which are level 1 inputs.

Fair Value, Measurements, Nonrecurring

Fair Value of Financial Instruments, Policy

The most significant non-recurring fair value measurements include the fair value of proved properties and tubular inventory and well materials for purposes of impairment testing and the initial determination of asset retirement obligations (“AROs”). The factors used to determine fair value for purposes of impairment testing include, but are not limited to, estimates of proved and probable reserves, future commodity prices, the timing of future production and capital expenditures and a discount rate commensurate with the risk reflective of the lives remaining for the respective oil and gas properties. Because these significant fair value inputs are typically not observable, we have categorized the amounts as level 3 inputs.

The determination of the fair value of AROs is based upon regional market and facility specific information. The amount of an ARO and the costs capitalized represent the estimated future cost to satisfy the abandonment obligation using current prices that are escalated by an assumed inflation factor after discounting the future cost back to the date that the abandonment obligation was incurred using a rate commensurate with the risk, which approximates our cost of funds. Because these significant fair value inputs are typically not observable, we have categorized the initial fair value estimates as level 3 inputs.