Debt and Other Obligations (Tables)

6 Months Ended

Jun. 30, 2017

Debt Disclosure [Abstract]

Schedule of Long-term Debt

Long-term debt is comprised of the following:

	As of				Three Months Ended June 30,				Six Months Ended June 30,
	June 30, 2017		December 31, 2016		2017		2016		2017		2016
	(in millions)				(weighted-average interest rates)
Fixed-rate senior term loans due through 2027	$	435.0	$	451.9	4.10	%	4.10	%	4.10	%	4.10	%
Fixed-rate junior term loans due through 2022	43.2		47.1		6.90	%	6.90	%	6.90	%	6.90	%
Fixed-rate loans due through 2029	216.3		—		3.82	%	N/A		3.82	%	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	$	1,218.1	$	1,012.4
Less current maturities	95.4		84.4
Less unamortized discounts	33.5		30.6
Total	$	1,089.2	$	897.4

Schedule of Maturities of Long-term Debt

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

	June 30, 2017
	(in millions)
Remainder of 2017	$	49.8
2018	97.9
2019	96.9
2020	96.1
2021	95.5
2022 and beyond	781.9
Total debt principal payments	$	1,218.1

Schedule of Interest Expense, Long-term Debt

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
	(in thousands)
Senior term loans	$	4,619	$	4,964	$	9,290	$	10,012
Junior term loans	775		905		1,578		1,842
Fixed-rate loans	1,586		—		1,744		—
Class A enhanced equipment trust certificates	4,321		2,698		8,629		3,881
Class B enhanced equipment trust certificates	1,108		773		2,292		1,109
Commitment fees	28		30		58		65
Amortization of debt discounts	1,290		794		2,521		1,310
Total	$	13,727	$	10,164	$	26,112	$	18,219