since 2013, while reducing outstanding shares by approximately 9% compared to the beginning of 2013. During 2015 alone, we repurchased and retired 48.4 million shares at a cost of $2.2 billion.

On February 3, 2016, the Board of Directors declared a $0.135 per share dividend for shareholders of record as of February 17, 2016.

Fuel Hedge Restructuring. During 2015, we effectively deferred settlement of a portion of our hedge portfolio until 2016 by entering into fuel derivative transactions that, excluding market movements from the date of inception, would settle and provide approximately $300 million in cash receipts during the second half of 2015 and require approximately $300 million in cash payments in 2016. We early terminated certain of these deferral transactions in 2015. As a result, we reported $429 million in cash receipts and $71 million in cash payments associated with these deferral transactions .

Undrawn Lines of Credit

We have $2.2 billion available in undrawn revolving lines of credit. Our credit facilities have covenants, including minimum collateral coverage ratios. If we are not in compliance with these covenants, we may be required to repay amounts borrowed under the credit facilities or we may not be able to draw on them. We currently have a substantial amount of unencumbered assets available to pledge as collateral.

Covenants

We were in compliance with the covenants in our financing agreements at December 31, 2015.

Contractual Obligations

The following table summarizes our contractual obligations at December 31, 2015 that we expect will be paid in cash. The table does not include amounts that are contingent on events or other factors that are uncertain or unknown at this time, including legal contingencies, uncertain tax positions and amounts payable under collective bargaining arrangements, among others. In addition, the table does not include expected significant cash payments representing obligations that arise in the ordinary course of business that do not include contractual commitments.

The amounts presented are based on various estimates, including estimates regarding the timing of payments, prevailing interest rates, volumes purchased, the occurrence of certain events and other factors. Accordingly, the actual results may vary materially from the amounts presented in the table.

Long-Term Debt, Principal Amount. Represents scheduled principal payments on long-term debt.

Long-Term Debt, Interest Payments. Represents estimated interest payments under our long-term debt based on the interest rates specified in the applicable debt agreements. Interest payments on variable interest rate debt were calculated using London interbank offered rates ("LIBOR") at December 31, 2015 .

Operating Lease Payments. Represents our minimum rental commitments under noncancelable operating leases (including certain aircraft flown by regional carriers).

Aircraft Purchase Commitments. Represents our commitments to purchase 70 B-737-900ER, 45 A321-200, 25 A330-900neo, 25 A350-900, 19 E190-100, 18 B-787-8 and six A330-300 aircraft. Our purchase commitment for the 18 B-787-8 aircraft provides for certain aircraft substitution