Note 6—Debt

Debt consisted of the following (in millions):

	March 31,		December 31,
	2016		2015
SHORT-TERM DEBT
Commercial paper notes, bearing a weighted-average interest rate of 0.9% and 1.1%, respectively (1)	$	137	$	696
Senior secured hedged inventory facility, bearing a weighted-average interest rate of 1.4% (1)	—		300
Senior notes:
5.88% senior notes due August 2016	175		—
6.13% senior notes due January 2017	400		—
Other	3		3

Total short-term debt	715		999

LONG-TERM DEBT
Senior notes, net of unamortized discounts and debt issuance costs of $74 and $77, respectively	9,126		9,698
Commercial paper notes, bearing a weighted-average interest rate of 0.9% and 1.1%, respectively	23		672
Other	4		5

Total long-term debt	9,153		10,375

Total debt (2)	$	9,868	$	11,374

(1)

We classified these commercial paper notes and credit facility borrowings as short-term as of March 31, 2016 and December 31, 2015, as these notes and borrowings were primarily designated as working capital borrowings, were required to be repaid within one year and were primarily for hedged NGL and crude oil inventory and NYMEX and ICE margin deposits.

(2)

Our fixed-rate senior notes (including current maturities) had a face value of approximately $9.8 billion as of both March 31, 2016 and December 31, 2015. We estimated the aggregate fair value of these notes as of March 31, 2016 and December 31, 2015 to be approximately $9.0 billion and $8.6 billion, respectively. Our fixed-rate senior notes are traded among institutions, and these trades are routinely published by a reporting service. Our determination of fair value is based on reported trading activity near the end of the reporting period. We estimate that the carrying value of outstanding borrowings under our credit facilities and commercial paper program approximates fair value as interest rates reflect current market rates. The fair value estimates for our senior notes, credit facilities and commercial paper program are based upon observable market data and are classified in Level 2 of the fair value hierarchy.

Borrowings and Repayments

Total borrowings under our credit facilities and commercial paper program for the three months ended March 31, 2016 and 2015 were approximately $10.8 billion and $7.0 billion, respectively. Total repayments under our credit facilities and commercial paper program were approximately $12.3 billion and $7.7 billion for the three months ended March 31, 2016 and 2015, respectively. The variance in total gross borrowings and repayments is impacted by various business and financial factors including, but not limited to, the timing, average term and method of general partnership borrowing activities.

Letters of Credit

In connection with our supply and logistics activities, we provide certain suppliers with irrevocable standby letters of credit to secure our obligation for the purchase of crude oil, NGL and natural gas. Additionally, we issue letters of credit to support insurance programs, derivative transactions and construction activities. At March 31, 2016 and December 31, 2015, we had outstanding letters of credit of $45 million and $46 million, respectively.