Fair Value Measurements (Tables)

6 Months Ended

Jun. 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 June 30, 2014
	Total		Level 1		Level 2		Level 3
	(in millions)
Cash and cash equivalents	$	567.2	$	567.2	$	—	$	—
Jet fuel options	0.4		—		—		0.4
Total assets	$	567.6	$	567.2	$	—	$	0.4
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 June 30, 2014
	(in thousands)
Balance at March 31, 2014	—
Total realized or unrealized gains (losses) included in earnings, net	(467		)
Purchases	827
Sales	—
Settlements, net	—
Balance at June 30, 2014	$	360

	Jet Fuel Option Activity for the Six Months Ended June 30, 2014
	(in thousands)
Balance at December 31, 2013	—
Total realized or unrealized gains (losses) included in earnings, net	(467		)
Purchases	827
Sales	—
Settlements, net	—
Balance at June 30, 2014	$	360