Segment Reporting (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)
Segment Reporting
Number of operating segments | segment										3
Number of reporting segments | segment									2
Operating revenues	$ 743,591	$ 760,295	$ 744,383	$ 723,694	$ 783,400	$ 805,515	$ 829,275	$ 803,489	$ 2,971,963	$ 3,221,679	$ 3,122,592
Operating expense									2,459,705	2,747,399	2,734,393
Depreciation and amortization expense									368,098	334,589	292,768
Special items		$ 21,900							21,869
Interest expense									127,755	120,409	104,925
Segment profit (loss)									384,503	353,871	283,274
Identifiable intangible assets, other than goodwill											4,896
Total assets	6,657,129				6,313,212				6,657,129	6,313,212	5,474,400
Capital expenditures (including non-cash)									846,470	1,156,276	689,398
SkyWest Airlines
Segment Reporting
Operating revenues									2,478,681	2,346,251	2,092,368
Operating expense									2,214,632	2,022,560	1,807,540
Depreciation and amortization expense									168,246	155,511	134,563
Special items									18,508
Interest expense									13,525	17,021	21,544
Segment profit (loss)									250,524	306,670	263,284
Total assets	2,728,964				2,531,707				2,728,964	2,531,707	2,245,051
Capital expenditures (including non-cash)									270,191	149,731	124,955
ExpressJet Airlines Inc
Segment Reporting
Operating revenues									24,050	564,202	790,282
Operating expense									28,690	577,608	818,683
Depreciation and amortization expense									971	37,290	51,982
Special items									3,361
Interest expense										2,340	4,127
Segment profit (loss)									(4,640)	(15,746)	(32,528)
Identifiable intangible assets, other than goodwill											4,896
Total assets					279,303					279,303	599,122
Capital expenditures (including non-cash)										10,137	14,278
SkyWest Leasing
Segment Reporting
Operating revenues									469,232	311,226	239,942
Operating expense									216,383	147,231	108,170
Depreciation and amortization expense									198,881	141,788	106,223
Interest expense									114,230	101,048	79,254
Segment profit (loss)									138,619	62,947	52,518
Total assets	$ 3,928,165				$ 3,502,202				3,928,165	3,502,202	2,630,227
Capital expenditures (including non-cash)									$ 576,279	$ 996,408	$ 550,165