The table below reflects long-term debt and capital lease obligations outstanding as of the dates indicated. In April 2018, all $84.7 million of our outstanding 3½% Convertible Senior Notes due 2024 was extinguished as a result of conversion into common stock (see April 2018 Conversion of 2024 Convertible Senior Notes below):



	March 31,			December 31,
In thousands	2018			2017
Senior Secured Bank Credit Agreement	$	450,000		$	475,000
9% Senior Secured Second Lien Notes due 2021	614,919			614,919
9¼% Senior Secured Second Lien Notes due 2022	455,668			381,568
5% Convertible Senior Notes due 2023	59,439			—
3½% Convertible Senior Notes due 2024	84,650			84,650
6⅜% Senior Subordinated Notes due 2021	203,545			215,144
5½% Senior Subordinated Notes due 2022	314,662			408,882
4⅝% Senior Subordinated Notes due 2023	307,978			376,501
Pipeline financings	189,547			192,429
Capital lease obligations	22,585			26,298
Total debt principal balance	2,702,993			2,775,391
Future interest payable⁽¹⁾	356,223			316,818
Debt issuance costs	(6,171		)	(7,935		)
Total debt, net of debt issuance costs	3,053,045			3,084,274
Less: current maturities of long-term debt⁽¹⁾	(129,667		)	(105,188		)
Long-term debt and capital lease obligations	$	2,923,378		$	2,979,086

(1)

Future interest payable represents most of the interest due over the terms of our 9% Senior Secured Second Lien Notes due 2021, 9¼% Senior Secured Second Lien Notes due 2022 (the “2022 Senior Secured Notes”), 5% Convertible Senior Notes due 2023 (the “2023 Convertible Senior Notes”), and 2024 Convertible Senior Notes and has been accounted for as debt in accordance with FASC 470-60, Troubled Debt Restructuring by Debtors. Our current maturities of long-term debt as of March 31, 2018 include $100.1 million of future interest payable related to these notes that is due within the next twelve months. See January 2018 Note Exchanges below for further discussion.