Segment Reporting (Details) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) segment aircraft	Dec. 31, 2017 USD ($)		Dec. 31, 2016 USD ($)
Segment Reporting
Number of operating segments | segment										3
Operating revenues		$ 803,489	$ 829,275	$ 805,515	$ 783,400	$ 771,241	$ 812,673	$ 791,512	$ 747,166	$ 3,221,679	$ 3,122,592	[1]	$ 3,063,702	[1]
Operating expense										2,747,399	2,734,393	[1]	3,236,386	[1]
Depreciation and amortization expense										334,589	292,768	[1]	284,969	[1]
Special items	[1]												465,649
Interest expense										120,409	104,925	[1]	78,177	[1]
Segment profit (loss)										353,871	283,274		(250,861)
Identifiable intangible assets, other than goodwill						4,896					4,896		8,249
Total assets		6,313,212				5,474,400				6,313,212	5,474,400		5,007,966
Capital expenditures (including non-cash)										$ 1,156,276	689,398		1,159,001
CRJ 200
Segment Reporting
Number of aircraft leased to third party | aircraft										4
Special items													424,466
SkyWest Airlines
Segment Reporting
Operating revenues										$ 2,346,251	2,092,368		1,878,725
Operating expense										2,022,560	1,807,540		1,829,520
Depreciation and amortization expense										155,511	134,563		139,159
Special items													184,295
Interest expense										17,021	21,544		26,211
Segment profit (loss)										306,670	263,284		22,994
Total assets		2,531,707				2,245,051				2,531,707	2,245,051		2,250,276
Capital expenditures (including non-cash)										149,731	124,955		57,761
SkyWest Airlines | CRJ 200
Segment Reporting
Special items													184,300
ExpressJet Airlines Inc
Segment Reporting
Operating revenues										564,202	790,282		1,043,977
Operating expense										577,608	818,683		1,338,718
Depreciation and amortization expense										37,290	51,982		83,935
Special items													281,354
Interest expense										2,340	4,127		6,773
Segment profit (loss)										(15,746)	(32,528)		(301,514)
Identifiable intangible assets, other than goodwill						4,896					4,896		8,249
Total assets		279,303				599,122				279,303	599,122		582,890
Capital expenditures (including non-cash)										10,137	14,278		15,396
ExpressJet Airlines Inc | CRJ 200
Segment Reporting
Special items													240,200
SkyWest Leasing
Segment Reporting
Operating revenues										311,226	239,942		141,000
Operating expense										147,231	108,170		68,148
Depreciation and amortization expense										141,788	106,223		61,875
Interest expense										101,048	79,254		45,193
Segment profit (loss)										62,947	52,518		27,659
Total assets		$ 3,502,202				$ 2,630,227				3,502,202	2,630,227		2,174,800
Capital expenditures (including non-cash)										$ 996,408	$ 550,165		$ 1,085,844

[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.