Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Carrying amount and estimated fair value, long-term debt

The carrying amounts and estimated fair values of the Company's long-term debt at March 31, 2018 and December 31, 2017 were as follows:

	March 31, 2018				December 31, 2017				Fair Value Level Hierarchy
	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value
	(in millions)
Senior term loans	$	409.1	$	414.0	$	417.9	$	435.3	Level 3
Junior term loans	37.3		37.8		39.3		40.4		Level 3
Fixed-rate loans	510.1		502.9		518.0		528.6		Level 3
2015-1 EETC Class A	408.6		409.8		408.6		420.9		Level 2
2015-1 EETC Class B	92.0		92.7		92.0		94.2		Level 2
2017-1 EETC Class AA	171.0		166.4		37.5		37.4		Level 2
2017-1 EETC Class A	57.0		55.2		12.5		12.6		Level 2
2017-1 EETC Class B	63.0		61.4		13.8		13.8		Level 2
Total long-term debt	$	1,748.1	$	1,740.2	$	1,539.6	$	1,583.2

Schedule of assets and liabilities measured at fair value on a recurring basis

Assets and liabilities measured at gross fair value on a recurring basis are summarized below:

	Fair Value Measurements as of March 31, 2018
	Total		Level 1		Level 2		Level 3
	(in millions)
Cash and cash equivalents	$	898.5	$	898.5	$	—	$	—
Short-term investment securities	101.3		101.3		—		—
Total assets	$	999.8	$	999.8	$	—	$	—
Total liabilities	$	—	$	—	$	—	$	—

	Fair Value Measurements as of December 31, 2017
	Total		Level 1		Level 2		Level 3
	(in millions)
Cash and cash equivalents	$	800.8	$	800.8	$	—	$	—
Short-term investment securities	100.9		100.9		—		—
Total assets	$	901.7	$	901.7	$	—	$	—
Total liabilities	$	—	$	—	$	—	$	—