13. DEBT

Debt consists of the following as of December 31:



(In thousands)	2018			2018			2017			2017
	Carrying Value			Estimated Fair Value			Carrying Value			Estimated Fair Value
3.84% Senior notes due 2021	100,000			100,359			100,000			102,472
3.70% Senior notes due 2023	202,500			201,813			225,000			228,783
3.85% Senior notes due 2025	90,000			89,711			100,000			102,164
4.24% Senior notes due 2026	200,000			202,288			200,000			208,873
4.05% Senior notes due 2028	67,500			66,942			75,000			76,997
4.11% Senior notes due 2028	90,000			89,647			100,000			103,226
Other debt	243			243			150			150
Total debt	750,243			751,003			800,150			822,665
Debt issuance costs, net	(714		)	(714		)	(831		)	(831		)
Unamortized interest rate swap proceeds	13,027			13,027			14,820			14,820
Total debt, net	762,556			763,316			814,139			836,654
Less: current portion of long-term debt and short-term debt	243			243			150			150
Total long-term debt	$	762,313		$	763,073		$	813,989		$	836,504

The weighted-average interest rate of the Corporation's Revolving Credit Agreement was 3.2% in 2018. The Corporation did not have any borrowings against the Revolving Credit Agreement in 2017.

The Corporation's total debt outstanding had weighted-average interest rates of 3.7% and 3.9% in 2018 and 2017, respectively.

Aggregate maturities of debt are as follows:



(In thousands)
2019	$	243
2020	—
2021	100,000
2022	—
2023	202,500
Thereafter	447,500
Total	$	750,243

Interest payments of $32 million, $39 million, and $38 million were made in 2018, 2017, and 2016, respectively.

Revolving Credit Agreement

In October 2018, the Corporation amended the terms of its existing 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 amended agreement, which provides the Corporation with a borrowing capacity of $500 million, extended the maturity date from November 2019 to October 2023 and expanded the accordion feature from $100 million to $200 million. 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. As of December 31, 2018, the Corporation had $22 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 as of December 31, 2018 was $478 million, which the Corporation had the ability to borrow in full without violating its debt to capitalization covenant.

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, the Corporation 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. On October 15, 2018, the Corporation made a discretionary $50 million prepayment on the $500 million 2013 Notes. 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, 2018, the Corporation had the ability to borrow additional debt of $1.4 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.

Interest Rate Swaps

On February 5, 2016, the Corporation terminated its fixed-to floating interest rate swap agreements on the 3.85% and 4.24% Senior Notes. As a result of the termination, the Corporation received a cash payment of $20.4 million, representing the fair value of the interest rate swaps on the date of termination. In connection with the termination, the Corporation and the counterparties released each other from all obligations under the interest rate swaps agreement, including, without limitation, the obligation to make periodic payments under such agreements. The gain on termination is reflected as a bond premium to the carrying value of the respective Senior Notes and will be amortized into interest expense over the remaining terms of the notes.