Financial Instruments

We utilize derivative financial instruments to manage exposure to certain risks related to our ongoing operations. The primary risks managed through the use of derivative instruments include interest rate risk, currency exchange risk, and commodity price risk. We do not use derivative instruments for trading or speculative purposes. While the majority of our derivative instruments are designated as hedging instruments, we also enter into derivative instruments that are designed to hedge a risk, but are not designated as hedging instruments. These derivative instruments are adjusted to current fair value through earnings at the end of each period. Our derivative and hedging programs are consistent with those described in the 2015 Form 10-K. The amount of ineffectiveness associated with these derivative instruments was immaterial for the three and six months ended December 31, 2015 and 2014.

During the three months ended December 31, 2015 and 2014, we entered into pay-floating interest rate swaps with total notional amounts of $300 million and $450 million, respectively. These swaps have been designated as fair value hedges of our fixed rate debt and are included in other assets in the condensed consolidated balance sheets.

During the three months ended September 30, 2014, we entered into forward interest rate swaps with a total notional amount of $50 million to hedge probable, but not firmly committed, future transactions associated with our debt.

In December 2014, we terminated notional amounts of $875 million of pay-floating interest rate swaps in connection with the debt redemption described in our 2015 10-K. These swaps were previously designated as fair value hedges. As a result of this redemption, we also incurred a loss on the extinguishment of debt of $60 million ($37 million, net of tax), which included a make-whole premium of $80 million, write-off of $2 million of unamortized debt issuance costs, and an offsetting $22 million fair value adjustment to the respective debt related to previously terminated interest rate swaps.

Fair Value of Financial Instruments

The carrying amounts of cash and equivalents, trade receivables, net, accounts payable, and other accrued liabilities at December 31, 2015 and June 30, 2015 approximate fair value due to their short-term maturities.

The following table summarizes the estimated fair value of our long-term obligations and other short-term borrowings compared to the respective carrying amounts at:



(in millions)	December 31, 2015		June 30, 2015
Estimated fair value	$	5,625	$	5,521
Carrying amount	5,525		5,492

The fair value of our long-term obligations and other short-term borrowings is estimated based on either the quoted market prices for the same or similar issues or other inputs derived from available market information, which represents a Level 2 measurement.