Long-term Debt (Tables)

3 Months Ended

Mar. 31, 2016

Debt Disclosure [Abstract]

Schedule of Long-term Debt

Long-term debt is comprised of the following:    

	As of				Three Months Ended March 31,
	March 31, 2016		December 31, 2015		2016		2015
	(in millions)				(weighted-average interest rates)
Fixed-rate senior term loans due through 2027	$	476.2	$	484.2	4.10	%	4.10	%
Fixed-rate junior term loans due through 2022	52.6		54.3		6.90	%	6.89	%
Fixed-rate class A enhanced equipment trust certificates due through 2028	154.2		95.8		4.03	%	N/A
Fixed-rate class B enhanced equipment trust certificates due through 2024	40.5		25.0		4.37	%	N/A
Long-term debt	$	723.5	$	659.3
Less current maturities	53.0		49.6
Less unamortized discounts, net	15.4		13.0
Total	$	655.1	$	596.7

Schedule of Maturities of Long-term Debt

At March 31, 2016, long-term debt principal payments for the next five years and thereafter are as follows:

	March 31, 2016
	(in millions)
remainder of 2016	$	45.0
2017	55.2
2018	58.4
2019	59.1
2020	59.2
2021 and thereafter	446.6
Total debt principal payments	$	723.5

Schedule of Interest Expense, Long-term Debt

Interest expense related to long-term debt consists of the following:

	Three Months Ended March 31
	2016		2015
	(in thousands)
Senior term loans	$	5,048	$	2,194
Junior term loans	937		419
Class A enhanced equipment trust certificates	1,183		—
Class B enhanced equipment trust certificates	336		—
Commitment fees	35		—
Amortization of debt discounts	516		159
Total	$	8,055	$	2,772