DEBT

A summary of long-term debt is as follows:



(In thousands)	March 31, 2016		September 30, 2015
6.5% Senior Notes due 2020 ("Senior Notes")	$	635,018	$	648,268
Revolving Credit Facility	960,000		1,030,000
Total long-term debt	$	1,595,018	$	1,678,268

Senior Notes

As of March 31, 2016, $636.5 million aggregate principal amount of our Senior Notes were outstanding. Our Senior Notes are presented in the table above net of the unamortized premium from their issuance and net of unamortized debt issuance costs of $6.7 million and $7.7 million as of March 31, 2016 and September 30, 2015, respectively. Our Senior Notes are unsecured obligations and are not guaranteed by any of our subsidiaries.

During the three months ended March 31, 2016, we repurchased, through open market transactions, $13.5 million aggregate principal of our Senior Notes at an aggregate cost of $5.1 million, including a minimal amount of accrued interest, representing an average discount of 62.2%. As a result of the repurchases, we recognized a total gain on debt retirement, net of the related debt issuance costs of $8.4 million ($8.4 million, net of tax, or $0.13 per diluted share) in Gains on extinguishment of debt on the Condensed Consolidated Statement of Operations for the three and six months ended March 31, 2016. The repurchases were made using available cash balances (see Note 9).

Revolving Credit Facility

On March 25, 2016, we entered into an amendment to our senior secured revolving credit facility (the "Credit Facility") providing that, among other things, effective on March 28, 2016, (i) removes the maximum leverage ratio and maximum secured leverage ratio financial covenants, (ii) amends the minimum interest expense coverage ratio such that it is not applicable until the quarter ending September 30, 2018, and decreases the minimum ratio required to 1.15:1.00, (iii) adds a minimum liquidity financial covenant of $150 million, (iv) revises the restricted payments covenant to prohibit us from paying dividends, (v) reduces the total commitments under the Credit Facility by $152 million, and (vi) permits the incurrence of up to $400 million of second lien debt, subject to the parameters set forth therein. After giving effect to the amendment, commitments under the Credit Facility are $1.395 billion through May 2018 and $1.1205 billion through May 2019. As a result of the amendment, borrowings under the Credit Facility will bear interest at the Eurodollar rate plus a margin ranging from 2.50% to 3.25% and the commitment fee on the unused portion of the underlying commitment ranges from 1.00% to 1.30% per annum, in each case based on our corporate credit ratings.

In connection with the amendment, we mortgaged the Atwood Achiever, the Atwood Advantage and the Atwood Orca, as additional collateral under the Credit Facility, as well as pledged the equity interests in our subsidiaries that own, directly or indirectly, these three vessels. Additionally, the Atwood Eagle and Atwood Falcon, along with the pledged equity interests in certain of our subsidiaries that, directly or indirectly, own these two vessels, were removed as collateral under the Credit Facility. Our interest in the two drillships under construction remain unencumbered by the Credit Facility.

As of March 31, 2016, our Credit Facility had $1.395 billion of total commitments and we had $960 million of outstanding borrowings. As of March 31, 2016, we had approximately $435 million available for borrowings under the Credit Facility. Approximately $275 million of the commitments mature in May 2018 and approximately $1.12 billion of the commitments under the Credit Facility mature in May 2019.

Obligations under the Credit Facility are secured primarily by first preferred mortgages on nine of our drilling units (Atwood Aurora, Atwood Beacon, Atwood Condor, Atwood Mako, Atwood Manta, Atwood Osprey, Atwood Achiever, Atwood Advantage and Atwood Orca), as well as liens on the equity interests of our subsidiaries that own, directly or indirectly, such drilling units. We were in compliance with all financial covenants under the Credit Facility as of March 31, 2016 and we anticipate that we will continue to be in compliance for the next 12 months.

The weighted-average effective interest rate on our long-term debt was approximately 4.30% per annum as of March 31, 2016. The effective rate was determined after giving consideration to the effect of our interest rate swaps accounted for as hedges and the amortization of debt issuance costs and our debt premiums. Interest capitalized for the three and six months ended March 31, 2016 was approximately $3.8 million and $8.4 million respectively. Interest capitalized for the three and six months ended March 31, 2015 was approximately $4 million and $9 million respectively.