Debt

The Company's $500.0 million syndicated credit facility (“Credit Agreement”) extends to June 2018. Interest on the borrowings under the Credit Agreement accrue at variable rates, based upon LIBOR or a defined “Base Rate,” both determined based upon the rating of the Company’s senior unsecured long-term debt (the “Debt Rating”). The applicable margin to be added to LIBOR ranges from 0.75% to 1.90% (1.25% as of December 31, 2015), and for Base Rate-determined loans, from 0.00% to 0.90% (0.25% as of December 31, 2015). The Company also pays a quarterly commitment fee ranging from 0.075% to 0.375% (0.150% as of December 31, 2015), determined based upon the Debt Rating, of the unused portion of the $500.0 million commitment under the Credit Agreement. In addition, the Company must pay certain letter of credit fees, ranging from 0.75% to 1.90% (1.25% as of December 31, 2015), with respect to letters of credit issued under the Credit Agreement. The Company has the right to voluntarily prepay and reborrow loans and to terminate or reduce the commitments under the facility. As of December 31, 2015, the Company had $7.6 million of issued letters of credit and $39.5 million of short-term borrowings under the Credit Agreement, with the balance of $452.9 million available to the Company.

The Company is subject to certain financial and restrictive covenants under the Credit Agreement, which, among other things, require the maintenance of a minimum interest coverage ratio of 3.50 to 1.00. The interest coverage ratio is defined in the Credit Agreement as, for any period, the ratio of consolidated earnings before interest, taxes, depreciation and amortization and non-cash net pension expense (“EBITDA”) to consolidated interest expense for such period. The Credit Agreement also requires the Company to maintain a debt to capital ratio of less than 55 percent. The debt to capital ratio is defined in the Credit Agreement as the ratio of consolidated indebtedness, as defined therein, to consolidated capitalization, as defined therein. As of December 31, 2015 and June 30, 2015, the Company was in compliance with all of the covenants of the Credit Agreement.

Long-term debt outstanding as of December 31, 2015 and June 30, 2015 consisted of the following:



($ in millions)	December 31, 2015		June 30, 2015
Medium-term notes, Series B at 6.97% to 7.10% due from April 2018 to May 2018 (face value of $55.0 million at December 31, 2015 and June 30, 2015)	$	55.0	$	55.0
Senior unsecured notes, 5.20% due July 2021 (face value of $250.0 million at December 31, 2015 and June 30, 2015)	253.7		252.5
Senior unsecured notes, 4.45% due March 2023 (face value of $300.0 million at December 31, 2015 and June 30, 2015)	299.7		299.6
Total	608.4		607.1
Less: amounts due within one year	—		—
Long-term debt, net of current portion	$	608.4	$	607.1

For the three months ended December 31, 2015 and 2014, interest costs totaled $7.5 million and $7.5 million, respectively, of which $0.5 million and $0.7 million, respectively, were capitalized as part of the cost of property, plant, equipment and software. For the six months ended December 31, 2015 and 2014, interest costs totaled $14.7 million and $15.1 million, respectively, of which $1.1 million and $1.3 million, respectively, were capitalized as part of the cost of property, plant, equipment and software.