Debt (Tables)

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Total debt as of December 31, 2019, and 2018, is summarized below:



Millions	2019		2018
Notes and debentures, 1.8% to 7.1% due through September 15, 2067	$	24,008	$	20,627
Equipment obligations, 2.6% to 6.2% due through January 2, 2031		923		969
Finance leases, 3.1% to 8.0% due through December 10, 2028		605		754
Receivables securitization (Note 11)		400		400
Term loans - floating rate, due through October 29, 2020		250		250
Commercial paper, 1.8% to 2.0% due through January 9, 2020		200		200
Medium-term notes, 9.3% to 10.0% due through April 15, 2020		8		8
Unamortized discount and deferred issuance costs		(1,194)		(817)
Total debt		25,200		22,391
Less: current portion		(1,257)		(1,466)
Total long-term debt	$	23,943	$	20,925

The following table presents aggregate debt maturities as of December 31, 2019, excluding market value adjustments:



Millions
2020	$	1,259
2021		1,256
2022		1,802
2023		1,391
2024		1,445
Thereafter		19,241
Total principal		26,394
Unamortized discount and deferred issuance costs		(1,194)
Total debt	$	25,200

During 2019, we issued the following unsecured, fixed-rate debt securities under our shelf registration:

On January 31, 2020, we issued the following in unsecured, fixed rate debt securities under our current shelf registration:



Date	Description of Securities
January 31, 2020	$500 million of 2.150% Notes due February 5, 2027
	$750 million of 2.400% Notes due February 5, 2030
	$1.0 billion of 3.250% Notes due February 5, 2050
	$750 million of 3.750% Notes due February 5, 2070