Income Taxes - Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Statutory Federal income tax rate (as a percent)	21.00%	35.00%		35.00%
Reconciliation
Computed provision (benefit) for income taxes at the statutory rate	$ 76,926	$ 100,864		$ (87,084)
State income tax provision (benefit), net of federal income tax benefit	12,711	7,778		(5,768)
Non-deductible expenses	1,956	3,230		3,552
Valuation allowance changes affecting the provision for income taxes	(1,187)	505		751
Foreign income taxes, net of federal & state benefit	1,192
Excess tax benefits from share based compensation	(4,548)	(5,377)
Revaluation of net deferred tax liabilities for the Tax Act		(246,845)
Other, net	(1,108)	(879)		1,323
Provision (benefit) for income taxes	85,942	(140,724)	[1]	(87,226)	[1]
Unrecorded tax benefits	14,553	2,223
Deferred tax assets:
Accrued benefits	32,462	31,651
Net operating loss carryforward	344,375	122,648
AMT credit carryforward	15,744	23,443
Aircraft credits	35,924	53,870
Accrued reserves and other	18,710	26,647
Total deferred tax assets	447,215	258,259
Valuation allowance	(9,455)	(10,642)
Deferred tax liabilities:
Accelerated depreciation	(955,919)	(666,637)
Total deferred tax liabilities	(955,919)	(666,637)
Net deferred tax liability	(518,159)	(419,020)
Accounting Standards Update 2016-09
Reconciliation
Benefit from share-based compensation	4,500	5,400
ExpressJet | State
Reconciliation
Valuation allowance	$ 1,200	$ 500		$ 800

[1] Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements of this report for additional information.