. DEBT

Debt consists of the following as of December 31:



(In thousands)	2016	2016	2015	2015
	Carrying Value	Estimated Fair Value	Carrying Value	Estimated Fair Value
5.51% Senior notes due 2017	150,000	154,509	150,000	158,024
3.84% Senior notes due 2021	100,000	102,463	100,307	100,307
3.70% Senior notes due 2023	225,000	226,946	225,000	224,322
3.85% Senior notes due 2025	100,000	100,338	100,450	100,450
4.24% Senior notes due 2026	200,000	203,592	201,422	201,422
4.05% Senior notes due 2028	75,000	74,630	75,904	75,904
4.11% Senior notes due 2028	100,000	99,876	100,000	99,720
Other debt	668	668	1,259	1,259
Total debt	950,668	963,022	954,342	961,408
Debt issuance costs, net	(984)	(984)	(1,137)	(1,137)
Unamortized interest rate swap proceeds	16,614	16,614	—	—
Total debt, net	966,298	978,652	953,205	960,271
Less: current portion of long-term debt and short-term debt	150,668	150,668	1,259	1,259
Total long-term debt	$815,630	$827,984	$951,946	$959,012

The Corporation did not have any borrowings against the Revolving Credit Agreement in 2016. The weighted-average interest rate of the Corporation’s Revolving Credit Agreement was 3.2% in 2015.

The debt outstanding had fixed and variable interest rates averaging 3.9% and 3.3% in 2016 and 2015, respectively.

Aggregate maturities of debt are as follows:



(In thousands)
2017	$	150,668
2018	—
2019	—
2020	—
2021	100,000
Thereafter	700,000
Total	$	950,668

Interest payments of $38 million, $33 million, and $33 million were made in 2016, 2015, and 2014, respectively.

Revolving Credit Agreement

In August 2012, the Corporation refinanced its existing credit facility by entering into a Third Amended and Restated Credit Agreement (Credit Agreement) with a syndicate of financial institutions, led by Bank of America N.A., Wells Fargo, N.A, and JP Morgan Chase Bank, N.A. The proceeds available under the Credit Agreement are to be used for working capital, internal growth initiatives, funding of future acquisitions, and general corporate purposes. Under the terms of the Credit Agreement, the Corporation has borrowing capacity of $500 million. In addition, the Credit Agreement provides an accordion feature which allows the Corporation to borrow an additional $100 million. As of December 31, 2016, the Corporation had $47 million in letters of credit supported by the credit facility and no borrowings outstanding under the credit facility. The unused credit available under the credit facility at December 31, 2016 was $453 million, which we had the ability to borrow in full without violating our debt to capitalization covenant.

In December 2014, the Corporation amended its existing credit facility by entering into a Second Amendment to the Third Amended and Restated Credit Agreement (Credit Agreement) with a syndicate of financial institutions, led by Bank of America N.A., Wells Fargo, N.A, and JP Morgan Chase Bank, N.A. The amendment extends the maturity date of the agreement to November 2019. No other material modifications were made to the 2012 Credit Agreement.

The Credit Agreement contains covenants that the Corporation considers usual and customary for an agreement of this type for comparable commercial borrowers, including a maximum consolidated debt to capitalization ratio of 60%. The Credit Agreement has customary events of default, such as non-payment of principal when due; nonpayment of interest, fees, or other amounts; cross-payment default and cross-acceleration.

Borrowings under the credit agreement will accrue interest based on (i) Libor or (ii) a base rate of the highest of (a) the federal funds rate plus 0.5%, (b) BofA’s announced prime rate, or (c) the Eurocurrency rate plus 1%, plus a margin. The interest rate and level of facility fees are dependent on certain financial ratios, as defined in the Credit Agreement. The Credit Agreement also provides customary fees, including administrative agent and commitment fees. In connection with the Credit Agreement, we paid customary transaction fees that have been deferred and are being amortized over the term of the Credit Agreement.

Senior Notes

On February 26, 2013, the Corporation issued $500 million of Senior Notes (the “2013 Notes”). The 2013 Notes consist of $225 million of 3.70% Senior Notes that mature on February 26, 2023, $100 million of 3.85% Senior Notes that mature on February 26, 2025, and $75 million of 4.05% Senior Notes that mature on February 26, 2028. $100 million of additional 4.11% Senior Notes were deferred and subsequently issued on September 26, 2013 that mature on September 26, 2028. The 2013 Notes are senior unsecured obligations, equal in right of payment to the Corporation’s existing senior indebtedness. The Corporation, at its option, can prepay at any time all or any part of the 2013 Notes, subject to a make-whole payment in accordance with the terms of the Note Purchase Agreement. In connection with the issuance of the 2013 Notes, the Corporation paid customary fees that have been deferred and are being amortized over the term of the 2013 Notes. Under the terms of the Note Purchase Agreement, the Corporation is required to maintain certain financial ratios, the most restrictive of which is a debt to capitalization limit of 60%. The debt to capitalization ratio (as defined per the Notes Purchase Agreement and Credit Agreement) is calculated using the same formula for all of the Corporation’s debt agreements and is a measure of the Corporation’s indebtedness to capitalization, where capitalization equals debt plus equity. As of December 31, 2016, the Corporation had the ability to borrow additional debt of $0.8 billion without violating our debt to capitalization covenant. The 2013 Notes also contain a cross default provision with respect to the Corporation’s other senior indebtedness.

On December 8, 2011, the Corporation issued $300 million of Senior Notes (the “2011 Notes”). The 2011 Notes consist of $100 million of 3.84% Senior Notes that mature on December 1, 2021 and $200 million of 4.24% Senior Series Notes that mature on December 1, 2026. The 2011 Notes are senior unsecured obligations, equal in right of payment to our existing senior indebtedness. The Corporation, at its option, can prepay at any time all or any part of our 2011 Notes, subject to a make-whole payment in accordance with the terms of the Note Purchase Agreement. In connection with our 2011 Notes, the Corporation paid customary fees that have been deferred and are being amortized over the term of our 2011 Notes. Under the Note Purchase Agreement, the Corporation is required to maintain certain financial ratios, the most restrictive of which is a debt to capitalization limit of 60%. The 2011 Notes also contain a cross default provision with our other senior indebtedness.

On December 1, 2005, the Corporation issued $150 million of 5.51% Senior Notes (the “2005 Notes”). The 2005 Notes mature on December 1, 2017. The Notes are senior unsecured obligations and are equal in right of payment to the Corporation’s existing senior indebtedness. The Corporation, at its option, can prepay at any time all or any part of the 2005 Notes, subject to a make-whole amount in accordance with the terms of the Note Purchase Agreement. In connection with the Notes, the Corporation paid customary fees that have been deferred and are being amortized over the terms of the Notes. The Corporation is required under the Note Purchase Agreement to maintain certain financial ratios, the most restrictive of which is a debt to capitalization limit of 60%. The 2005 Notes also contain a cross default provision with the Corporation’s other senior indebtedness.