2. Debt and Financing Arrangements

At December 31, debt consisted of the following (in thousands):

	December 31, 2017		December 31, 2016
Credit Agreement with Banks, described below	$	43,000	$	—
Senior Notes under a Master Shelf Agreement, described below		—		7,143
Capital Leases, described below		89,916		66,661
Total debt		132,916		73,804
Less: current portion of long-term debt		14,083		16,762
Long-term debt, less current portion	$	118,833	$	57,042

The Company’s liquidity needs arise primarily from capital investment in new equipment, land and structures, information technology and letters of credit required under insurance programs, as well as funding working capital requirements.

The Company is party to a revolving credit agreement with a group of banks to fund capital investments, letters of credit and working capital needs. The Company has pledged certain land and structures, tractors and trailers, accounts receivable and other assets to secure indebtedness under this agreement.

Restated Credit Agreement

On March 6, 2015, the Company entered into the Fifth Amended and Restated Credit Agreement with its banking group (as amended, the Restated Credit Agreement). The Restated Credit Agreement increased the revolving credit facility availability from $200 million to $250 million and extended the term until March 2020. The Restated Credit Agreement also reduced the interest rate pricing grid and eliminated both the borrowing base and the minimum tangible net worth covenant.

The Restated Credit Agreement also has an accordion feature that allows for an additional $75 million of availability, subject to lender approval. The Restated Credit Agreement provides for a LIBOR rate margin range from 112.5 basis points to 225 basis points, base rate margins from minus 12.5 basis points to plus 50 basis points, an unused portion fee from 20 basis points to 30 basis points and letter of credit fees from 112.5 basis points to 225 basis points in each case based on the Company’s leverage ratio.

Under the Restated Credit Agreement, the Company must maintain certain financial covenants including a minimum fixed charge coverage ratio and a maximum leverage ratio, among others. The Restated Credit Agreement also provides for a pledge by the Company of certain land and structures, certain tractors, trailers and other personal property and accounts receivable, to secure indebtedness under the Restated Credit Agreement.

At December 31, 2017, the Company had borrowings of $43.0 million and outstanding letters of credit of $33.9 million under the Restated Credit Agreement. At December 31, 2016, the Company had no outstanding borrowings and outstanding letters of credit of $39.4 million under the Restated Credit Agreement. The available portion of the Restated Credit Agreement may be used for general corporate purposes, including capital expenditures, working capital and letter of credit requirements as needed.

Restated Master Shelf Agreement

In 2002, the Company issued $100 million in Senior Notes under a $125 million (amended to $150 million in April 2005) Master Shelf Agreement with Prudential Investment Management, Inc. and certain of its affiliates. The Company issued another $25 million in Senior Notes on November 30, 2007 and $25 million in Senior Notes on January 31, 2008 under the same Master Shelf Agreement.

The November 2007 issuance of $25 million Senior Notes had a fixed interest rate of 6.14 percent. The January 2008 issuance of $25 million Senior Notes had a fixed interest rate of 6.17 percent. Payments due for both $25 million issuances were interest only until June 30, 2011 and at that time semi-annual principal payments began with the final payments made on December 31, 2017. Under the terms of the Senior Notes, the Company was required to maintain certain financial covenants including a minimum fixed charge coverage ratio and a maximum leverage ratio, among others. The Senior Notes also provided for a pledge by the Company of certain land and structures, certain tractors, trailers and other personal property and accounts receivable, to secure indebtedness under the Senior Notes. At December 31, 2016, the Company had $7.1 million in Senior Notes outstanding. Upon maturity in December 2017, the Company paid off the outstanding balance of the Senior Notes.

Capital Leases

The Company is obligated under capital leases with seven year terms which include obligations covering revenue equipment totaling $89.9 million and $66.7 million as of December 31, 2017 and 2016, respectively. Amortization of assets held under the capital leases is included in depreciation and amortization expense. The weighted average interest rate for the capital leases at December 31, 2017 and 2016 is 3.07% and 2.82%, respectively.

Other

The Company paid cash for interest of $2.3 million, $2.4 million, and $3.0 million for the years ended December 31, 2017, 2016 and 2015, respectively.

The estimated fair value of total debt at December 31, 2017 and 2016 is $132.3 million and $77.6 million, respectively. The carrying amount of debt related to the revolving credit facility approximated fair value as of December 31, 2017 and 2016 due to the existence of variable interest rates, which approximate market rates. The fair value of the Senior Notes as of December 31, 2016 is based on undiscounted cash flows at market interest rates for similar issuances of private debt which reflect Level 2 inputs in the fair value hierarchy. The fair value of the capital leases is based on current market interest rates for similar types of financial instruments which reflect Level 2 inputs.

Principal Maturities of Long-Term Debt

The principal maturities of long-term debt, including interest on capital leases, for the next five years (in thousands) are as follows:

	Amount
2018	$	16,652
2019		16,652
2020		59,652
2021		17,230
2022		15,794
Thereafter		15,667
Total		141,647
Less: Amounts Representing Interest on Capital Leases		8,731
Total	$	132,916