(in thousands)	March 31, 2019			December 31, 2018			March 31, 2018
Senior notes payable	$	40,000		$	40,000		$	80,000
Credit Agreement term loan		144,375			146,250			88,750
Credit Agreement revolving credit loan		197,000			197,000			55,000
Debt issuance costs		(804	)		(845	)		(441	)
Total debt		380,571			382,405			223,309
Less current maturities		47,281			47,286			47,298
Total long-term debt	$	333,290		$	335,119		$	176,011

The aggregate minimum principal maturities of long-term debt, including current maturities and excluding debt issuance costs, related to balances at March 31, 2019 are as follows: $45.6 million during the remainder of 2019; $7.5 million in 2020; $7.5 million in 2021; $7.5 million in 2022 and $313.3 million in 2023.

Senior notes payable as of both March 31, 2019 and December 31, 2018 of $40.0 million and $80.0 million as of March 31, 2018 were due to a group of institutional holders and had an interest rate of 6.11% per annum (“2019 Notes”). As of March 31, 2019 and December 31, 2018, all of the $40.0 million was included in current maturities of long-term debt on the condensed consolidated balance sheets. As of March 31, 2018, $40.0 million of the outstanding balance was included in each current maturities of long-term debt and long-term debt in the condensed consolidated balance sheets.

Granite entered into the Third Amended and Restated Credit Agreement dated May 31, 2018 (the “Credit Agreement”). The Credit Agreement provided for a $150.0 million term loan, of which $144.4 million was outstanding on March 31, 2019, and a $350.0 million revolving credit facility, of which $197.0 million was outstanding as of March 31, 2019.

The term loan required that Granite repay 1.25% of the principal balance during each of the quarters ended December 31, 2018 and March 31, 2019. The term loan requires that Granite repay 1.25% of the principal balance each quarter until the maturity date, at which point the remaining balance is due. As of each March 31, 2019, December 31, 2018 and March 31, 2018, $7.5 million of the term loan balance was included in current maturities of long-term debt on the condensed consolidated balance sheets and the remaining $136.9 million, $138.8 million and $81.3 million, respectively, was included in long-term debt.

As of March 31, 2019, the total stated amount of all issued and outstanding letters of credit under the Credit Agreement was $32.5 million. As of both March 31, 2019 and December 31, 2018, $197.0 million and as of March 31, 2018, $55.0 million was outstanding under the revolving credit facility. As of March 31, 2019, the total unused availability under the Credit Agreement was $120.5 million. The letters of credit will expire between June and November 2019.

Borrowings under the Credit Agreement bear interest at LIBOR or a base rate (at our option), plus an applicable margin based on the Consolidated Leverage Ratio (as defined in the Credit Agreement) calculated quarterly. The applicable margin was 1.63% for loans bearing interest based on LIBOR and 0.63% for loans bearing interest at the base rate at March 31, 2019. Accordingly, the effective interest rate using three-month LIBOR and base rate was 4.22% and 6.13%, respectively, at March 31, 2019 and we elected to use LIBOR for both the term loan and the revolving credit facility.

As of March 31, 2019, the conditions for the exercise of our right under Credit Agreement to have liens released were not satisfied.

As of March 31, 2019 and pursuant to the definitions in the agreement governing the 2019 Notes, which are more restrictive, our Consolidated Tangible Net Worth was $1.1 billion, which exceeded the minimum of $794.2 million, our Consolidated Leverage Ratio was 1.96 which did not exceed the maximum of 3.00. Our Consolidated Interest Coverage Ratio was 11.70 which exceeded the minimum of 4.00.

As of March 31, 2019, we were in compliance with all covenants contained in the Credit Agreement and the agreement governing the 2019 Notes. We are not aware of any non-compliance by any of our unconsolidated entities with any covenants contained in their debt agreements.