Segment Reporting (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)		Sep. 30, 2018 USD ($) segment aircraft	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	[1]
Segment Reporting
Number of operating segments | segment				3
Operating revenues	$ 829,275	$ 812,673	[1]	$ 2,418,190	$ 2,351,351
Operating expenses	691,350	700,304	[1]	2,065,412	2,056,092
Depreciation and amortization expense	86,088	74,095	[1]	246,386	215,415
Interest expense	31,440	27,101	[1]	86,485	78,713
Segment profit (loss)	109,925	86,676	[1]	275,455	219,944
Identifiable intangible assets, other than goodwill	1,224	6,121		1,224	6,121
Total assets	6,184,860	5,373,995		6,184,860	5,373,995	$ 5,474,400
Capital expenditures (including non-cash)	321,566	53,499		954,071	572,400
Segments
Segment Reporting
Segment profit (loss)	106,485	85,268		266,293	216,546
SkyWest Airlines
Segment Reporting
Operating revenues	607,052	558,994		1,750,827	1,543,618
Operating expenses	512,278	472,000		1,505,298	1,331,931
Depreciation and amortization expense	39,651	34,049		115,979	98,396
Interest expense	4,044	5,276		12,722	16,811
Total assets	2,251,563	2,072,597		2,251,563	2,072,597
Capital expenditures (including non-cash)	44,689	27,118		121,010	85,895
SkyWest Airlines | Segments
Segment Reporting
Segment profit (loss)	90,730	81,718		232,807	194,876
ExpressJet Airlines Inc
Segment Reporting
Operating revenues	140,155	191,368		444,943	631,634
Operating expenses	139,736	200,344		455,084	644,490
Depreciation and amortization expense	8,683	12,573		30,044	38,808
Interest expense	649	1,017		2,264	3,219
Identifiable intangible assets, other than goodwill	1,224	6,121		1,224	6,121
Total assets	565,266	721,939		565,266	721,939
Capital expenditures (including non-cash)	3,069	2,259		5,996	12,414
ExpressJet Airlines Inc | Segments
Segment Reporting
Segment profit (loss)	(230)	(9,993)		(12,405)	(16,075)
SkyWest Leasing
Segment Reporting
Operating revenues	82,068	62,311		222,420	176,099
Operating expenses	39,336	27,960		105,030	79,671
Depreciation and amortization expense	37,754	27,473		100,363	78,211
Interest expense	26,747	20,808		71,499	58,683
Total assets	3,368,031	2,579,459		3,368,031	2,579,459
Capital expenditures (including non-cash)	273,808	24,122		$ 827,065	474,091
SkyWest Leasing | CRJ 200
Segment Reporting
Number of aircraft | aircraft				4
SkyWest Leasing | Segments
Segment Reporting
Segment profit (loss)	$ 15,985	$ 13,543		$ 45,891	$ 37,745

[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 contained in Part I, Item 1 of this report for additional information.