Note 7—Debt

Debt consisted of the following (in millions):

	March 31,		December 31,
	2013		2012
SHORT-TERM DEBT
Credit Facilities :
PAA senior secured hedged inventory facility, bearing a weighted-average interest rate of 1.3% and 1.6% at March 31, 2013 and December 31, 2012, respectively	$	325	$	665
PAA senior unsecured revolving credit facility, bearing a weighted-average interest rate of 1.5% and 2.4% at March 31, 2013 and December 31, 2012, respectively (1)	18		92
PNG senior unsecured revolving credit facility, bearing a weighted-average interest rate of 2.1% at both March 31, 2013 and December 31, 2012 (2)	93		77
5.63% senior notes due December 2013 (3)	250		250
Other	3		2
Total short-term debt	689		1,086

LONG-TERM DEBT
Senior notes, net of unamortized discounts of $15 at both March 31, 2013 and December 31, 2012.	6,010		6,010

Credit Facilities and Other:
PNG senior unsecured revolving credit facility, bearing a weighted-average interest rate of 2.1% at both March 31, 2013 and December 31, 2012 (2)	116		105
PNG GO Bond term loans, bearing a weighted-average interest rate of 1.5% at both March 31, 2013 and December 31, 2012	200		200
Other	5		5
Total long-term debt	6,331		6,320
Total debt (1) (2) (4)	$	7,020	$	7,406

(1) We classify as short-term certain borrowings under our PAA senior unsecured revolving credit facility. These borrowings are primarily designated as working capital borrowings, must be repaid within one year and are primarily for hedged NGL and crude oil inventory and NYMEX and ICE margin deposits.

(2) PNG classifies as short-term debt any borrowings under the PNG senior unsecured revolving credit facility that have been designated as working capital borrowings and must be repaid within one year. Such borrowings are primarily related to a portion of PNG’s hedged natural gas inventory.

(3) Our $250 million 5.63% senior notes will mature in December 2013 and are thus classified as short-term at March 31, 2013 and December 31, 2012.

(4) Our fixed-rate senior notes (including current maturities) had a face value of approximately $6.3 billion at both March 31, 2013 and December 31, 2012. We estimated the aggregate fair value of these notes as of March 31, 2013 and December 31, 2012 to be approximately $7.2 billion and $7.3 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 quarter end. We estimate that the carrying value of outstanding borrowings under our credit facilities and agreements approximates fair value as interest rates reflect current market rates. The fair value estimates for both our senior notes and credit facilities and agreements are based upon observable market data and are classified within level 2 of the fair value hierarchy.

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. At March 31, 2013 and December 31, 2012, we had outstanding letters of credit of approximately $56 million and $24 million, respectively.