Debt

3 Months Ended

Mar. 31, 2021

Debt consisted of the following (in millions):


	March 31, 2021		December 31, 2020
SHORT-TERM DEBT
Commercial paper notes, bearing a weighted-average interest rate of 0.6% and 0.7%, respectively (1)	$	137	$	547
Senior secured hedged inventory facility, bearing a weighted-average interest rate of 1.2% (1)	—		167




Other	117		117
Total short-term debt	254		831

LONG-TERM DEBT
Senior notes, net of unamortized discounts and debt issuance costs of $60 and $62, respectively	9,073		9,071


GO Zone term loans, net of debt issuance costs of $1 and $1, respectively, bearing a weighted-average interest rate of 1.3% and 1.3%, respectively	199		199
Other	66		112
Total long-term debt	9,338		9,382
Total debt (2)	$	9,592	$	10,213

(1)We classified these commercial paper notes as short-term as of March 31, 2021 and December 31, 2020, respectively, and these credit facility borrowings as short-term as of December 31, 2020, 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 had a face value of approximately $9.1 billion at both March 31, 2021 and December 31, 2020. We estimated the aggregate fair value of these notes as of March 31, 2021 and December 31, 2020 to be approximately $9.5 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 the end of the reporting period. We estimate that the carrying value of outstanding borrowings under our credit facilities, commercial paper program and GO Zone term loans approximates fair value as interest rates reflect current market rates. The fair value estimates for our senior notes, credit facilities, commercial paper program and GO Zone term loans 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, 2021 and 2020 were approximately $14.2 billion and $9.6 billion, respectively. Total repayments under our credit facilities and commercial paper program were approximately $14.8 billion and $9.6 billion for the three months ended March 31, 2021 and 2020, 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 and transportation of crude oil, NGL and natural gas. Additionally, we issue letters of credit to support insurance programs, derivative transactions, including hedging-related margin obligations, and construction activities. At March 31, 2021 and December 31, 2020, we had outstanding letters of credit of $130 million and $129 million, respectively.