Debt consisted of the following as of the dates indicated (in millions):

	March 31,		December 31,
	2015		2014
SHORT-TERM DEBT
Commercial paper notes, bearing a weighted-average interest rate of 0.46% at December 31, 2014 (1)	$	—	$	734
Senior notes:
5.25% senior notes due June 2015	150		150
3.95% senior notes due September 2015	400		400
Other	3		3
Total short-term debt	553		1,287

LONG-TERM DEBT
Senior notes, net of unamortized discount of $17 and $18, respectively	8,758		8,757
Other	5		5
Total long-term debt	8,763		8,762
Total debt (2)	$	9,316	$	10,049

(1)

At December 31, 2014, we classified all of the borrowings under our commercial paper program as short-term as these borrowings were primarily designated as working capital borrowings, must 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 $9.3 billion as of both March 31, 2015 and December 31, 2014. We estimated the aggregate fair value of these notes as of March 31, 2015 and December 31, 2014 to be approximately $10.0 billion and $9.9 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 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.