Long-term Debt (Tables)

9 Months Ended

Sep. 30, 2016

Debt Disclosure [Abstract]

Schedule of Long-term Debt

Long-term debt is comprised of the following:    

	As of				Three Months Ended September 30,				Nine Months Ended September 30,
	September 30, 2016		December 31, 2015		2016		2015		2016		2015
	(in millions)				(weighted-average interest rates)
Fixed-rate senior term loans due through 2027	$	460.1	$	484.2	4.10	%	4.10	%	4.10	%	4.10	%
Fixed-rate junior term loans due through 2022	48.9		54.3		6.90	%	6.90	%	6.90	%	6.90	%
Fixed-rate class A enhanced equipment trust certificates due through 2028	394.8		95.8		4.03	%	N/A		4.03	%	N/A
Fixed-rate class B enhanced equipment trust certificates due through 2024	104.5		25.0		4.38	%	N/A		4.38	%	N/A
Long-term debt	$	1,008.3	$	659.3
Less current maturities	84.4		49.6
Less unamortized discounts, net	29.1		13.0
Total	$	894.8	$	596.7

Schedule of Maturities of Long-term Debt

At September 30, 2016, long-term debt principal payments for the next five years and thereafter were as follows:

	September 30, 2016
	(in millions)
remainder of 2016	$	34.7
2017	84.6
2018	80.4
2019	79.1
2020	77.3
2021 and thereafter	652.2
Total debt principal payments	$	1,008.3

Schedule of Interest Expense, Long-term Debt

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

	Three Months Ended September 30				Nine Months Ended September 30,
	2016		2015		2016		2015
	(in thousands)
Senior term loans	$	4,917	$	4,639	$	14,929	$	10,260
Junior term loans	879		926		2,721		2,023
Class A enhanced equipment trust certificates	3,538		—		7,419		—
Class B enhanced equipment trust certificates	1,015		—		2,124		—
Commitment fees	32		—		97		—
Amortization of debt discounts	979		340		2,289		729
Total	$	11,360	$	5,905	$	29,579	$	13,012