Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2014

Fair Value Disclosures [Abstract]

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 September 30, 2014
	Total		Level 1		Level 2		Level 3
	(in millions)
Cash and cash equivalents	$	588.5	$	588.5	$	—	$	—
Jet fuel options	0.1		—		—		0.1
Total assets	$	588.6	$	588.5	$	—	$	0.1
Total liabilities	$	—	$	—	$	—	$	—

	Fair Value Measurements as of December 31, 2013
	Total		Level 1		Level 2		Level 3
	(in millions)
Cash and cash equivalents	$	530.6	$	530.6	$	—	$	—
Total assets	$	530.6	$	530.6	$	—	$	—
Total liabilities	$	—	$	—	$	—	$	—

Schedule of assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3)

The following table presents the Company's activity for assets and liabilities measured at gross fair value on a recurring basis using significant unobservable inputs (Level 3):

	Jet Fuel Option Activity for the Three Months Ended September 30, 2014
	(in thousands)
Balance at June 30, 2014	360
Total realized or unrealized gains (losses) included in earnings, net	(446		)
Purchases	164
Sales	—
Settlements, net	—
Balance at September 30, 2014	$	78

	Jet Fuel Option Activity for the Nine Months Ended September 30, 2014
	(in thousands)
Balance at December 31, 2013	—
Total realized or unrealized gains (losses) included in earnings, net	(913		)
Purchases	991
Sales	—
Settlements, net	—
Balance at September 30, 2014	$	78