Debt

Short-Term Debt

We have a debt financing program of up to $3.0 billion through the issuance of commercial paper. Net proceeds from this program are used for general corporate purposes. As of December 31, 2014 and June 30, 2015, we had $2.0 billion of outstanding commercial paper recorded as short-term debt with weighted-average interest rates of 0.1%. In conjunction with this program, we have a $3.0 billion revolving credit facility which expires in July 2016. The interest rate for the credit facility is determined based on a formula using certain market rates. As of December 31, 2014 and June 30, 2015, we were in compliance with the financial covenants in the credit facility, and no amounts were outstanding under the credit facility as of December 31, 2014 and June 30, 2015. The estimated fair value of the commercial paper approximated its carrying value as of December 31, 2014 and June 30, 2015.

Our short-term debt balance also includes the short-term portion of certain long-term debt, as described in the section below.

Long-Term Debt

We issued $1.0 billion of unsecured senior notes (the "2014 Notes") in February 2014 and $3.0 billion of unsecured senior notes in three tranches (collectively, the "2011 Notes") in May 2011. We used the net proceeds from the issuance of the 2011 Notes to repay a portion of our outstanding commercial paper and for general corporate purposes. We used the net proceeds from the issuance of the 2014 Notes for the repayment of the portion of the principal amount of our 2011 Notes which matured on May 19, 2014 and for general corporate purposes. The total outstanding Notes are summarized below (in millions):



	As of December 31, 2014			As of June 30, 2015
				(unaudited)
Short-Term Portion of Long-Term Debt
2.125% Notes due on May 19, 2016⁽¹⁾	$	0		$	999
Capital Lease Obligation	10			9
Total	$	10		$	1,008

Long-Term Debt
2.125% Notes due on May 19, 2016	$	1,000		$	0
3.625% Notes due on May 19, 2021	1,000			1,000
3.375% Notes due on February 25, 2024	1,000			1,000
Unamortized discount for the Notes above	(8		)	(6		)
Subtotal	2,992			1,994
Capital Lease Obligation	236			231
Total	$	3,228		$	2,225


⁽¹⁾	The outstanding Notes as of June 30, 2015 are net of unamortized discount of $1 million.

The effective interest yields of the Notes due in 2016, 2021, and 2024 were 2.241%, 3.734% and 3.377%, respectively. Interest on the 2011 and 2014 Notes is payable semi-annually. The 2011 and 2014 Notes rank equally with each other and with all of our other senior unsecured and unsubordinated indebtedness from time to time outstanding. We may redeem the 2011 and 2014 Notes at any time in whole or in part at specified redemption prices. We are not subject to any financial covenants under the 2011 Notes or the 2014 Notes. The total estimated fair value of the outstanding 2011 and 2014 Notes was approximately $3.1 billion as of December 31, 2014 and June 30, 2015. The fair value of the outstanding 2011 and 2014 Notes was determined based on observable market prices of identical instruments in less active markets and is categorized accordingly as Level 2 in the fair value hierarchy.

In August 2013, we entered into a capital lease obligation on certain property which expires in 2028 with an option to purchase the property in 2016. The effective rate of the capital lease obligation approximates the market rate. The estimated fair value of the capital lease obligation approximated its carrying value as of December 31, 2014 and June 30, 2015.