Segment Reporting (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) segment aircraft	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting
Number of operating segments | segment									3
Operating revenues	$ 797,158	$ 831,936	$ 809,759	$ 765,415	$ 758,017	$ 799,776	$ 801,338	$ 762,075	$ 3,204,268	$ 3,121,206	$ 3,095,563
Operating expense									2,816,069	3,293,890	2,861,048
Depreciation and amortization expense									292,768	284,969	264,507
Special items					465,600					465,649
Interest expense									104,925	78,177	75,850
Segment profit (loss)									283,274	(250,861)	158,665
Identifiable intangible assets, other than goodwill	4,896				8,249				4,896	8,249	10,499
Total assets	5,458,279				5,007,966				5,458,279	5,007,966	4,781,984
Capital expenditures (including non-cash)									$ 689,398	1,159,001	715,089
CRJ 200
Segment Reporting
Number of aircraft lease to third party | aircraft									4
Special items										424,466
SkyWest Airlines
Segment Reporting
Operating revenues									$ 2,173,384	1,935,378	1,848,363
Operating expense									1,888,556	1,886,173	1,630,200
Depreciation and amortization expense									134,563	139,159	141,189
Special items										184,295
Interest expense									21,544	26,211	36,141
Segment profit (loss)									263,284	22,994	182,022
Total assets	2,228,930				2,250,276				2,228,930	2,250,276	2,300,388
Capital expenditures (including non-cash)									124,955	57,761	30,897
ExpressJet Airlines Inc
Segment Reporting
Operating revenues									790,942	1,044,828	1,169,923
Operating expense									819,343	1,339,569	1,192,070
Depreciation and amortization expense									51,982	83,935	86,382
Special items										281,354
Interest expense									4,127	6,773	12,091
Segment profit (loss)									(32,528)	(301,514)	(34,238)
Identifiable intangible assets, other than goodwill	4,896				8,249				4,896	8,249	10,499
Total assets	599,122				582,890				599,122	582,890	1,331,000
Capital expenditures (including non-cash)									14,278	15,396	24,679
ExpressJet Airlines Inc | CRJ 200
Segment Reporting
Special items									240,200
SkyWest Leasing
Segment Reporting
Operating revenues									239,942	141,000	77,277
Operating expense									108,170	68,148	38,778
Depreciation and amortization expense									106,223	61,875	36,936
Interest expense									79,254	45,193	27,618
Segment profit (loss)									52,518	27,659	10,881
Total assets	$ 2,630,227				$ 2,174,800				2,630,227	2,174,800	1,150,596
Capital expenditures (including non-cash)									$ 550,165	$ 1,085,844	$ 659,513