DEBT

Long-term debt consisted of the following:



	December 31
($ in millions)	2018		2017
Senior notes due November 15, 2025, 5.000%	600		600
Senior notes due December 1, 2027, 3.483%	600		600
Mississippi economic development revenue bonds due May 1, 2024, 7.81%	84		84
Gulf opportunity zone industrial development revenue bonds due December 1, 2028, 4.55%	21		21
Less unamortized debt issuance costs	(22	)	(26	)
Total long-term debt	1,283		1,279

Credit Facility - In November 2017, the Company terminated its Second Amended and Restated Credit Agreement and entered into a new Credit Agreement (the "Credit Facility") with third-party lenders. The Credit Facility includes a revolving credit facility of $1,250 million, which may be drawn upon during a period of five years from November 22, 2017. The revolving credit facility includes a letter of credit subfacility of $500 million. The revolving credit facility has a variable interest rate on outstanding borrowings based on the London Interbank Offered Rate ("LIBOR") plus a spread based upon the Company's credit ratings, which may vary between 1.125% and 1.500%. The revolving credit facility also has a commitment fee rate on the unutilized balance based on the Company’s credit ratings. The commitment fee rate as of December 31, 2018 was 0.25% and may vary between 0.20% and 0.30%.

The Credit Facility contains customary affirmative and negative covenants, as well as a financial covenant based on a maximum total leverage ratio. Each of the Company's existing and future material wholly owned domestic subsidiaries, except those that are specifically designated as unrestricted subsidiaries, are and will be guarantors under the Credit Facility.

As of December 31, 2018, approximately $16 million in letters of credit were issued but undrawn, and the remaining $1,234 million of the revolving credit facility was unutilized. The Company had unamortized debt issuance costs associated with its credit facilities of $8 million and $11 million as of December 31, 2018 and 2017, respectively.

Senior Notes - In December 2017, the Company issued $600 million aggregate principal amount of 3.483% senior notes with registration rights due December 2027, the net proceeds of which were used to repurchase the Company's 5.000% senior notes due 2021. Pursuant to the terms of the registration rights agreement entered into in connection with the issuance of these senior notes, the Company completed in June 2018 an exchange of $600 million aggregate principal amount of registered 3.483% senior notes due December 2027 for all of the then outstanding unregistered senior notes due December 2027. The Company also has outstanding $600 million aggregate principal amount of unregistered 5.000% senior notes due November 2025. Interest on the Company's senior notes is payable semi-annually.

The terms of the senior notes limit the Company’s ability and the ability of certain of its subsidiaries to create liens, enter into sale and leaseback transactions, sell assets, and effect consolidations or mergers. The Company had unamortized debt issuance costs associated with the senior notes of $14 million and $15 million as of December 31, 2018 and 2017, respectively.

Early Extinguishment of Debt - Details of the loss on early extinguishment of debt related to the Company's prior credit facility and refinancing of senior notes, which was included in interest expense, were as follows:



	Year Ended
($ in millions)	December 31, 2017
Redemption and tender premiums and fees	$	15
Write-off of unamortized debt issuance costs	7
Total loss on early extinguishment of debt	$	22

Mississippi Economic Development Revenue Bonds - As of each of December 31, 2018 and 2017, the Company had $84 million outstanding under Industrial Revenue Bonds issued by the Mississippi Business Finance Corporation. These bonds accrue interest at a fixed rate of 7.81% per annum (payable semi-annually) and mature in 2024.

Gulf Opportunity Zone Industrial Development Revenue Bonds - As of each of December 31, 2018 and 2017, the Company had $21 million outstanding under Gulf Opportunity Zone Industrial Development Revenue Bonds issued by the Mississippi Business Finance Corporation. These bonds accrue interest at a fixed rate of 4.55% per annum (payable semi-annually) and mature in 2028.

The Company's debt arrangements contain customary affirmative and negative covenants. The Company was in compliance with all debt covenants during the year ended December 31, 2018.

The estimated fair values of the Company's total long-term debt as of December 31, 2018, and December 31, 2017, were $1,292 million and $1,361 million, respectively. The fair values of the Company's long-term debt were calculated based on recent trades of the Company's debt instruments in inactive markets, which fall within Level 2 under the fair value hierarchy.

The Company does not have any principal payments due on long-term debt within the next five years.