Passenger and Ground Handling Revenue (Details) - aircraft	3 Months Ended	9 Months Ended
	Mar. 31, 2017	Dec. 31, 2017
Agreements with other airlines
Percentage of ASMs flown under fixed-fee arrangements	95.90%
Percentage of ASMs flown under pro-rate arrangements	4.10%
Sky West Airlines Inc | Delta Connection Prorate Agreement
Agreements with other airlines
Term of agreement	30 days
Sky West Airlines Inc | United Express Prorate Agreement
Agreements with other airlines
Term of agreement	120 days
Sky West Airlines Inc | American Prorate Agreement
Agreements with other airlines
Term of agreement	120 days
ExpressJet | American Prorate Agreement
Agreements with other airlines
Term of agreement	120 days
CRJ 200 | Sky West Airlines Inc | Delta Connection Agreements
Agreements with other airlines
Number of aircraft under contract	51
CRJ 200 | Sky West Airlines Inc | Delta Connection Prorate Agreement
Agreements with other airlines
Number of aircraft under contract	24
CRJ 200 | Sky West Airlines Inc | United Express Agreements
Agreements with other airlines
Number of aircraft under contract	42
CRJ 200 | Sky West Airlines Inc | Alaska Capacity Purchase Agreement
Agreements with other airlines
Number of aircraft under contract	22
CRJ 200 | Sky West Airlines Inc | American Capacity Purchase Agreement
Agreements with other airlines
Number of aircraft under contract	22
CRJ 200 | Sky West Airlines Inc | American Prorate Agreement
Agreements with other airlines
Number of aircraft under contract	6
CRJ 200 | ExpressJet | Delta Connection Agreements
Agreements with other airlines
Number of aircraft under contract	32
CRJ 200 | ExpressJet | American Capacity Purchase Agreement
Agreements with other airlines
Number of aircraft under contract	6
CRJ 200 | ExpressJet | American Prorate Agreement
Agreements with other airlines
Number of aircraft under contract	3
CRJ 700 | Sky West Airlines Inc | Delta Connection Agreements
Agreements with other airlines
Number of aircraft under contract	27
CRJ 700 | Sky West Airlines Inc | United Express Agreements
Agreements with other airlines
Number of aircraft under contract	29
CRJ 700 | Sky West Airlines Inc | Alaska Capacity Purchase Agreement
Agreements with other airlines
Number of aircraft under contract	1
CRJ 700 | Sky West Airlines Inc | American Capacity Purchase Agreement
Agreements with other airlines
Number of aircraft under contract	28
CRJ 700 | ExpressJet | Delta Connection Agreements
Agreements with other airlines
Number of aircraft under contract	35
CRJ 700 | ExpressJet | American Capacity Purchase Agreement
Agreements with other airlines
Number of aircraft under contract	10
CRJ 900 | Sky West Airlines Inc | Delta Connection Agreements
Agreements with other airlines
Number of aircraft under contract	36
CRJ 900 | ExpressJet | Delta Connection Agreements
Agreements with other airlines
Number of aircraft under contract	28
E 175 | Forecast | Delta Connection Agreements
Agreements with other airlines
Number of aircraft under contract		6
E 175 | Forecast | United Express Agreements
Agreements with other airlines
Number of aircraft under contract		5
E 175 | Sky West Airlines Inc | Delta Connection Agreements
Agreements with other airlines
Number of aircraft under contract	13
E 175 | Sky West Airlines Inc | United Express Agreements
Agreements with other airlines
Number of aircraft under contract	60
E 175 | Sky West Airlines Inc | Alaska Capacity Purchase Agreement
Agreements with other airlines
Number of aircraft under contract	20
ERJ 145 | ExpressJet | United Express Agreements
Agreements with other airlines
Number of aircraft under contract	126
ERJ 145 | ExpressJet | American Capacity Purchase Agreement
Agreements with other airlines
Number of aircraft under contract	6
ERJ 135 | ExpressJet | United Express Agreements
Agreements with other airlines
Number of aircraft under contract	5