Segment Reporting (Details) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)		Jun. 30, 2018 USD ($) segment aircraft	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	[1]
Segment Reporting
Number of operating segments | segment				3
Operating revenues	$ 805,515	$ 791,512	[1]	$ 1,588,915	$ 1,538,678
Operating expenses	678,837	684,916	[1]	1,374,062	1,355,788
Depreciation and amortization expense	82,714	71,206	[1]	160,298	141,320
Interest expense	28,811	27,063	[1]	55,045	51,612
Segment profit (loss)	98,327	80,863	[1]	165,530	133,268
Identifiable intangible assets, other than goodwill	2,448	7,124		2,448	7,124
Total assets	5,913,093	5,345,145		5,913,093	5,345,145	$ 5,474,400
Capital expenditures (including non-cash)	364,717	295,802		632,505	518,901
Segments
Segment Reporting
Segment profit (loss)	97,867	79,533		159,808	131,278
SkyWest Airlines
Segment Reporting
Operating revenues	587,480	519,708		1,143,775	984,624
Operating expenses	494,143	442,600		993,019	859,931
Depreciation and amortization expense	38,841	32,530		76,327	64,347
Interest expense	4,202	5,735		8,678	11,535
Total assets	2,222,784	2,235,863		2,222,784	2,235,863
Capital expenditures (including non-cash)	40,039	25,346		76,322	58,777
SkyWest Airlines | Segments
Segment Reporting
Segment profit (loss)	89,135	71,373		142,078	113,158
ExpressJet Airlines Inc
Segment Reporting
Operating revenues	143,707	211,819		304,788	440,266
Operating expenses	148,525	214,864		315,349	444,146
Depreciation and amortization expense	10,200	11,710		21,362	26,235
Interest expense	788	1,088		1,615	2,202
Identifiable intangible assets, other than goodwill	2,448	7,124		2,448	7,124
Total assets	563,198	529,175		563,198	529,175
Capital expenditures (including non-cash)	1,588	4,501		2,926	10,155
ExpressJet Airlines Inc | Segments
Segment Reporting
Segment profit (loss)	(5,606)	(4,133)		(12,176)	(6,082)
SkyWest Leasing
Segment Reporting
Operating revenues	74,328	59,985		140,352	113,788
Operating expenses	36,169	27,452		65,694	51,711
Depreciation and amortization expense	33,673	26,966		62,609	50,738
Interest expense	23,821	20,240		44,752	37,875
Total assets	3,127,111	2,580,107		3,127,111	2,580,107
Capital expenditures (including non-cash)	323,090	265,955		$ 553,257	449,969
SkyWest Leasing | CRJ 200
Segment Reporting
Number of aircraft | aircraft				4
SkyWest Leasing | Segments
Segment Reporting
Segment profit (loss)	$ 14,338	$ 12,293		$ 29,906	$ 24,202

[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.