Flying Agreements Revenue and Airport Customer Service and Other Revenue (Details) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)		Jun. 30, 2018 USD ($) aircraft item	Jun. 30, 2017 USD ($)
Agreements with other airlines
Percentage of ASMs flown under fixed-fee arrangements				84.70%
Percentage of ASMs flown under pro-rate arrangements				15.30%
Revenues [Abstract]
Operating revenues | $	$ 805,515	$ 791,512	[1]	$ 1,588,915	$ 1,538,678
Sky West Airlines Inc | Delta Connection Prorate Agreement
Revenues [Abstract]
Term of agreement				30 days
Sky West Airlines Inc | United Express Prorate Agreement
Revenues [Abstract]
Term of agreement				120 days
Sky West Airlines Inc | American Capacity Purchase Agreement
Revenues [Abstract]
Number of aircraft				7
Sky West Airlines Inc | American Prorate Agreement
Revenues [Abstract]
Term of agreement				120 days
CRJ 200 | Sky West Airlines Inc | Delta Connection Agreements
Revenues [Abstract]
Number of aircraft				60
CRJ 200 | Sky West Airlines Inc | Delta Connection Prorate Agreement
Revenues [Abstract]
Number of aircraft				34
CRJ 200 | Sky West Airlines Inc | United Express Agreements
Revenues [Abstract]
Number of aircraft				64
CRJ 200 | Sky West Airlines Inc | United Express Prorate Agreement
Revenues [Abstract]
Number of aircraft				21
CRJ 200 | Sky West Airlines Inc | American Capacity Purchase Agreement
Revenues [Abstract]
Number of aircraft				10
CRJ 200 | Sky West Airlines Inc | American Prorate Agreement
Revenues [Abstract]
Number of aircraft				7
CRJ 200 | Sky West Airlines Inc | Alaska Capacity Purchase Agreement
Revenues [Abstract]
Number of aircraft				2
CRJ 200 | ExpressJet | American Capacity Purchase Agreement
Revenues [Abstract]
Number of aircraft				16
CRJ 700 | Sky West Airlines Inc | Delta Connection Agreements
Revenues [Abstract]
Number of aircraft				27
CRJ 700 | Sky West Airlines Inc | United Express Agreements
Revenues [Abstract]
Number of aircraft				20
CRJ 700 | Sky West Airlines Inc | American Capacity Purchase Agreement
Revenues [Abstract]
Number of aircraft				38
CRJ 700 | ExpressJet | Delta Connection Agreements
Revenues [Abstract]
Number of aircraft				22
CRJ 700 | Delta
Revenues [Abstract]
Number of aircraft				20
CRJ 700 | American
Revenues [Abstract]
Number of additional aircraft placed into service				20
CRJ 700 | United
Revenues [Abstract]
Number of aircraft				19
CRJ 900 | Sky West Airlines Inc | Delta Connection Agreements
Revenues [Abstract]
Number of aircraft				36
CRJ 900 | Delta
Revenues [Abstract]
Number of additional aircraft placed into service				20
E 175
Revenues [Abstract]
Number of seats on aircraft | item				76
E 175 | Sky West Airlines Inc | Delta Connection Agreements
Revenues [Abstract]
Number of aircraft				32
E 175 | Sky West Airlines Inc | United Express Agreements
Revenues [Abstract]
Number of aircraft				65
E 175 | Sky West Airlines Inc | Alaska Capacity Purchase Agreement
Revenues [Abstract]
Number of aircraft				29
E 175 | Alaska
Revenues [Abstract]
Number of additional aircraft placed into service				6
Number of additional aircraft placed into service, deferred				3
E 175 | Delta
Revenues [Abstract]
Number of additional aircraft placed into service				17
E175 SC
Revenues [Abstract]
Number of seats on aircraft | item				70
ERJ 145 | ExpressJet | United Express Agreements
Revenues [Abstract]
Number of aircraft				97
ERJ 135 | ExpressJet | United Express Agreements
Revenues [Abstract]
Number of aircraft				3
Flying agreements
Revenues [Abstract]
Operating revenues | $	793,637	781,724	[1]	$ 1,561,602	1,516,253
Flight operations
Revenues [Abstract]
Operating revenues | $	462,824	459,350		931,849	905,069
Aircraft rentals
Revenues [Abstract]
Operating revenues | $	201,306	208,669		390,375	407,132
Prorate agreements
Revenues [Abstract]
Operating revenues | $	$ 129,507	$ 113,705		$ 239,378	$ 204,052

[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.