DEBT

The carrying value of long-term debt as of December 31, 2015 and 2014 consisted of the following (in millions):



	2015		2014
4.70% Senior notes due 2021	$	1,482.7	$	1,479.9
5.75% Senior notes due 2044	1,004.2		622.3
6.875% Senior notes due 2020	990.9		1,008.2
5.20% Senior notes due 2025	697.6		—
4.50% Senior notes due 2024	624.3		624.2
8.50% Senior notes due 2019	566.4		583.8
7.875% Senior notes due 2040	379.8		381.2
7.20% Debentures due 2027	149.2		149.2
3.25% Senior notes due 2016	—		998.0
4.33% MARAD bonds due 2016	—		46.6
4.65% MARAD bonds due 2020	—		27.0
Total debt	5,895.1		5,920.4
Less current maturities	—		(34.8		)
Total long-term debt	$	5,895.1	$	5,885.6

Senior Notes

During the first quarter, we issued $700.0 million aggregate principal amount of unsecured 5.20% senior notes due 2025 (the “2025 Notes”) at a discount of $2.6 million and $400.0 million aggregate principal amount of unsecured 5.75% senior notes due 2044 (the “New 2044 Notes”) at a discount of $18.7 million in a public offering. Interest on the 2025 Notes is payable semiannually on March 15 and September 15 of each year commencing September 15, 2015. Interest on the New 2044 Notes is payable semiannually on April 1 and October 1 of each year commencing on April 1, 2015.

During 2014, we issued $625.0 million aggregate principal amount of unsecured 4.50% senior notes due 2024 (the "2024 Notes") at a discount of $850,000 and $625.0 million aggregate principal amount of unsecured 5.75% senior notes due 2044 (the "Existing 2044 Notes" and together with the New 2044 Notes, the "2044 Notes") at a discount of $2.8 million. Interest on the 2024 Notes and the Existing 2044 Notes is payable semiannually on April 1 and October 1 of each year commencing on April 1, 2015. The Existing 2044 Notes and the New 2044 Notes are treated as a single series of debt securities under the indenture governing the notes (the "2044 Notes").

During 2011, we issued $1.5 billion aggregate principal amount of unsecured 4.70% senior notes due 2021 (the “2021 Notes”) at a discount of $29.6 million in a public offering. Interest on the 2021 Notes is payable semiannually on March 15 and September 15 of each year.

Upon consummation of the Pride acquisition during 2011, we assumed the acquired company's outstanding debt comprised of $900.0 million aggregate principal amount of unsecured 6.875% senior notes due 2020, $500.0 million aggregate principal amount of unsecured 8.5% senior notes due 2019 and $300.0 million aggregate principal amount of unsecured 7.875% senior notes due 2040 (collectively, the "Acquired Notes" and together with the 2021 Notes, 2024 Notes, 2025 Notes and 2044 Notes, the "Senior Notes"). Ensco plc has fully and unconditionally guaranteed the performance of all Pride obligations with respect to the Acquired Notes. See "Note 15 - Guarantee of Registered Securities" for additional information on the guarantee of the Acquired Notes.

We may redeem the 2024 Notes, 2025 Notes and 2044 Notes in whole, at any time or in part from time to time, prior to maturity. If we elect to redeem the 2024 Notes and 2025 Notes before the date that is three months prior to the maturity date or the 2044 Notes before the date that is six months prior to the maturity date, we will pay an amount equal to 100% of the principal amount of the notes redeemed plus accrued and unpaid interest and a "make-whole" premium. If we elect to redeem the 2024 Notes, 2025 Notes or 2044 Notes on or after the aforementioned dates, we will pay an amount equal to 100% of the principal amount of the notes redeemed plus accrued and unpaid interest but we are not required to pay a "make-whole" premium.

We may redeem each series of the 2021 Notes and the Acquired Notes, in whole or in part, at any time, at a price equal to 100% of their principal amount, plus accrued and unpaid interest and a "make-whole" premium.

The indentures governing the Senior Notes contain customary events of default, including failure to pay principal or interest on such notes when due, among others. The indentures governing the Senior Notes also contain certain restrictions, including, among others, restrictions on our ability and the ability of our subsidiaries to create or incur secured indebtedness, enter into certain sale/leaseback transactions and enter into certain merger or consolidation transactions.

Debentures Due 2027

During 1997, Ensco Delaware issued $150.0 million of unsecured 7.20% Debentures due November 15, 2027 (the "Debentures") in a public offering. Interest on the Debentures is payable semiannually in May and November. We may redeem the Debentures, in whole or in part, at any time prior to maturity, at a price equal to 100% of their principal amount, plus accrued and unpaid interest and a "make-whole" premium. The Debentures are not subject to any sinking fund requirements. During 2009, in connection with the redomestication, Ensco plc entered into a supplemental indenture to unconditionally guarantee the principal and interest payments on the Debentures.

The Debentures and the indenture pursuant to which the Debentures were issued also contain customary events of default, including failure to pay principal or interest on the Debentures when due, among others. The indenture also contains certain restrictions, including, among others, restrictions on our ability and the ability of our subsidiaries to create or incur secured indebtedness, enter into certain sale/leaseback transactions and enter into certain merger or consolidation transactions.

Redemption of 2016 Senior Notes and MARAD Obligations

During 2011, we issued $1.0 billion of 3.25% senior notes due 2016 (the “2016 Notes”). In March 2015, we commenced a cash tender offer (the “Tender Offer”) for the 2016 Notes. Tendered notes totaling $854.6 million were settled on March 12, 2015 for $878.0 million (excluding accrued interest) using a portion of the net proceeds from the issuance of the 2025 Notes and New 2044 Notes. Under the terms of the Tender Offer, we paid a premium totaling approximately $23.4 million, which approximates the “make-whole” premium that would have been required had we elected to redeem the debt. Additionally, we recorded charges of $1.7 million for unamortized debt discounts and $1.5 million for unamortized debt issuance costs, resulting in a total pre-tax loss on debt extinguishment of $26.6 million included in other, net, in our consolidated statement of operations for the year ended December 31, 2015.

Concurrent with the settlement of the Tender Offer, we exercised our right to redeem the remaining 2016 Notes. In April 2015, we completed the redemption of the remaining $145.4 million of 2016 Notes using a portion of the net proceeds from the 2025 Notes and New 2044 Notes. The redemption payment included a "make-whole" premium of $3.8 million which was recorded as a loss on debt extinguishment and included in other, net, in our consolidated statement of operations for the year ended December 31, 2015.

In April 2015, we used the remaining net proceeds from the 2025 Notes and New 2044 Notes, together with cash on hand, to redeem $51.0 million of our 4.33% MARAD notes due 2016 and 4.65% MARAD bonds due 2020 (the “MARAD Obligations”). We incurred additional losses on debt extinguishment of $3.1 million, which were included in other, net, in our consolidated statement of operations for the year ended December 31, 2015. These losses primarily consisted of a "make-whole" premium.

In July 2015, we redeemed the remaining $14.3 million aggregate principal amount of the MARAD Obligations.

Commercial Paper

We participate in a commercial paper program with three commercial paper dealers pursuant to which we may issue, on a private placement basis, unsecured commercial paper notes up to a maximum aggregate amount outstanding at any time of $2.25 billion. Amounts issued under the commercial paper program are supported by the available and unused committed capacity under our credit facility. As a result, amounts issued under the commercial paper program are limited by the amount of our available and unused committed capacity under our credit facility. The proceeds of such financings may be used for capital expenditures and other general corporate purposes. The commercial paper bears interest at rates that vary based on market conditions and the ratings assigned by credit rating agencies at the time of issuance. If we are downgraded below investment grade by one or more credit rating agencies, we may have limited or no access to the commercial paper market. The weighted-average interest rate on our commercial paper borrowings was 0.41% and 0.26% during 2015 and 2014, respectively. Commercial paper maturities will vary but may not exceed 364 days from the date of issue. The commercial paper is not redeemable or subject to voluntary prepayment by us prior to maturity. We had no amounts outstanding under our commercial paper program as of December 31, 2015 and 2014.

Revolving Credit

We have a $2.25 billion senior unsecured revolving credit facility with a syndicate of banks to be used for general corporate purposes with a term expiring on September 30, 2019 (the "Credit Facility").

Advances under the Credit Facility bear interest at Base Rate or LIBOR plus an applicable margin rate, depending on our credit ratings. We are required to pay a quarterly commitment fee on the undrawn portion of the $2.25 billion commitment, which is also based on our credit ratings.

During the fourth quarter, Moody's and Standard & Poor's downgraded our senior unsecured rating one notch to Baa2 and BBB, respectively. As a result, the applicable margin rate for advances under our Credit Facility and the quarterly commitment fee percentage increased by 0.125% per annum and 0.025% per annum, respectively, under our Credit Facility. Currently, the applicable margin rates are 0.25% per annum for Base Rate advances and 1.25% per annum for LIBOR advances. Also, our quarterly commitment fee is 0.15% per annum on the undrawn portion of the $2.25 billion commitment. Amounts repaid may be re-borrowed during the term of the Credit Facility. There can be no assurance that ratings agencies will not further downgrade our credit ratings, and any such further downgrade, or the perceived risk of further downgrades, may limit our ability to access debt capital markets, restructure or refinance our debt, result in higher borrowing costs or require more restrictive terms and covenants, which may further restrict our operations.

The Credit Facility requires us to maintain a total debt to total capitalization ratio that is less than or equal to a specified percentage. In March 2015, we amended the Credit Facility to increase the percentage from 50% to 60%. The Credit Facility also contains customary restrictive covenants, including, among others, prohibitions on creating, incurring or assuming certain debt and liens; entering into certain merger arrangements; selling, leasing, transferring or otherwise disposing of all or substantially all of our assets; making a material change in the nature of the business; and entering into certain transactions with affiliates. We have the right, subject to receipt of commitments from lenders, to increase the commitments under the Credit Agreement to an aggregate amount of up to $2.75 billion and to extend the term of the Credit Agreement by one year on up to two occasions.

As of December 31, 2015, we were in compliance in all material respects with our covenants under the Credit Facility. We expect to remain in compliance with our Credit Facility covenants during 2016. We had no amounts outstanding under the Credit Facility as of December 31, 2015 and 2014.

Maturities

The aggregate maturities of our debt, excluding net unamortized premiums of $195.1 million, as of December 31, 2015 were as follows (in millions):



2016	$	—
2017	—
2018	—
2019	500.0
2020	900.0
Thereafter	4,300.0
Total	$	5,700.0

Interest expense totaled $216.3 million, $161.4 million and $158.8 million for the years ended December 31, 2015, 2014 and 2013, respectively, which was net of interest amounts capitalized of $87.4 million, $78.2 million and $67.7 million in connection with newbuild rig construction and other capital projects.