Debt and Other Obligations (Tables)

9 Months Ended

Sep. 30, 2017

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, 2017		December 31, 2016		2017		2016		2017		2016
	(in millions)				(weighted-average interest rates)
Fixed-rate senior term loans due through 2027	$	426.4	$	451.9	4.10	%	4.10	%	4.10	%	4.10	%
Fixed-rate junior term loans due through 2022	41.3		47.1		6.90	%	6.90	%	6.90	%	6.90	%
Fixed-rate loans due through 2029	363.4		—		3.76	%	N/A		3.76	%	N/A
Fixed-rate class A enhanced equipment trust certificates due through 2028	423.6		409.8		4.10	%	4.03	%	4.10	%	4.03	%
Fixed-rate class B enhanced equipment trust certificates due through 2024	100.0		103.6		4.45	%	4.38	%	4.45	%	4.38	%
Long-term debt	$	1,354.7	$	1,012.4
Less current maturities	106.0		84.4
Less unamortized discounts	34.6		30.6
Total	$	1,214.1	$	897.4

Schedule of Maturities of Long-term Debt

At September 30, 2017, long-term debt principal payments for the next five years and thereafter are as follows:

	September 30, 2017
	(in millions)
Remainder of 2017	$	39.0
2018	108.0
2019	107.5
2020	107.1
2021	106.9
2022 and beyond	886.2
Total debt principal payments	$	1,354.7

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,
	2017		2016		2017		2016
	(in thousands)
Senior term loans	$	4,564	$	4,917	$	13,854	$	14,929
Junior term loans	746		879		2,323		2,721
Fixed-rate loans	2,811		—		4,555		—
Class A enhanced equipment trust certificates	4,366		3,538		12,995		7,419
Class B enhanced equipment trust certificates	1,118		1,015		3,410		2,124
Commitment fees	29		32		87		97
Amortization of debt discounts	1,362		979		3,883		2,289
Total	$	14,996	$	11,360	$	41,107	$	29,579