14. Financial Instruments

Strategy and Risk – We may use derivative financial instruments in limited instances for other than trading purposes to assist in managing our overall exposure to fluctuations in interest rates and fuel prices. We are not a party to leveraged derivatives and, by policy, do not use derivative financial instruments for speculative purposes. Derivative financial instruments qualifying for hedge accounting must maintain a specified level of effectiveness between the hedging instrument and the item being hedged, both at inception and throughout the hedged period. We formally document the nature and relationships between the hedging instruments and hedged items at inception, as well as our risk-management objectives, strategies for undertaking the various hedge transactions, and method of assessing hedge effectiveness. Changes in the fair market value of derivative financial instruments that do not qualify for hedge accounting are charged to earnings. We may use swaps, collars, futures, and/or forward contracts to mitigate the risk of adverse movements in interest rates and fuel prices; however, the use of these derivative financial instruments may limit future benefits from favorable interest rate and fuel price movements.

Market and Credit Risk – We address market risk related to derivative financial instruments by selecting instruments with value fluctuations that highly correlate with the underlying hedged item. We manage credit risk related to derivative financial instruments, which is minimal, by requiring high credit standards for counterparties and periodic settlements. At December 31, 2014, and 2013, we were not required to provide collateral, nor had we received collateral, relating to our hedging activities.

Interest Rate Fair Value Hedges – We manage our overall exposure to fluctuations in interest rates by adjusting the proportion of fixed and floating rate debt instruments within our debt portfolio over a given period. We generally manage the mix of fixed and floating rate debt through the issuance of targeted amounts of each as debt matures or as we require incremental borrowings. We employ derivatives, primarily swaps, as one of the tools to obtain the targeted mix. In addition, we also obtain flexibility in managing interest costs and the interest rate mix within our debt portfolio by evaluating the issuance of and managing outstanding callable fixed-rate debt securities.

Swaps allow us to convert debt from fixed rates to variable rates and thereby hedge the risk of changes in the debt's fair value attributable to the changes in interest rates. We account for swaps as fair value hedges using the short-cut method; therefore, we do not record any ineffectiveness within our Consolidated Financial Statements. As of December 31, 2014, and 2013, we had no interest rate fair value hedges outstanding.

Interest Rate Cash Flow Hedges – We report changes in the fair value of cash flow hedges in accumulated other comprehensive loss until the hedged item affects earnings. At December 31, 2014, and 2013, we had reductions of $0 and $1 million, respectively, recorded as an accumulated other comprehensive loss. As of December 31, 2014, and 2013, we had no interest rate cash flow hedges outstanding.

Earnings Impact – Our use of derivative financial instruments had no impact on pre-tax income for the years ended December 31, 2014, 2013, and 2012.

Fair Value of Financial Instruments – The fair value of our short- and long-term debt was estimated using a market value price model, which utilizes applicable U.S. Treasury rates along with current market quotes on comparable debt securities. All of the inputs used to determine the fair market value of the Corporation's long-term debt are Level 2 inputs and obtained from an independent source. At December 31, 2014, the fair value of total debt was $13.0 billion, approximately $1.5 billion more than the carrying value. At December 31, 2013, the fair value of total debt was $10.2 billion, approximately $0.6 billion more than the carrying value. The fair value of the Corporation's debt is a measure of its current value under present market conditions. It does not impact the financial statements under current accounting rules. At both December 31, 2014, and 2013, approximately $163 million of debt securities contained call provisions that allow us to retire the debt instruments prior to final maturity, with the payment of fixed call premiums, or in certain cases, at par. The fair value of our cash equivalents approximates their carrying value due to the short-term maturities of these instruments.