Nature of Operations and Summary of Significant Accounting Policies - Agreements (Details)	3 Months Ended	12 Months Ended
	Dec. 31, 2016 item	Dec. 31, 2018 aircraft	Dec. 31, 2017 agreement aircraft item
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			623
Number of seats on aircraft | item	50
CRJ 200
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			208
CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			136
CRJ 700 | Forecast
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft removed from service		8
CRJ 900
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			52
CRJ 700s/900s
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft operated | agreement			49
CRJ 700s/900s | Forecast
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of leased aircraft returned		19
Number of aircraft removed from service		30
E 175
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			107
Number of seats on aircraft | item			76
E 175 | Forecast
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of additional aircraft placed into service		12
E175 SC
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of seats on aircraft | item			70
E175 SC | Forecast
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of additional aircraft placed into service		30
ERJ 135
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			3
ERJ 145
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			117
EMB 120
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft removed from service			11
Number of seats on aircraft | item			30
Delta Connection Agreements | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			70
Delta Connection Agreements | CRJ 700 | ExpressJet
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			33
Delta Connection Agreements | CRJ 900 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			36
Delta Connection Agreements | CRJ 900 | ExpressJet
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			16
Delta Connection Agreements | E 175 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			19
Term of agreement			2 years 10 months 24 days
Delta Connection Prorate Agreements | CRJ 200 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			24
Term of agreement			30 days
Delta Connection Prorate Agreements | CRJ 700 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			27
United Express Agreements | CRJ 200 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			57
United Express Agreements | CRJ 700 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			20
United Express Agreements | E 175 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			65
Term of agreement			5 years 1 month 6 days
United ERJ Agreements | ERJ 135 | ExpressJet
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			3
Term of agreement			4 years 9 months 18 days
United ERJ Agreements | ERJ 145 | ExpressJet
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			109
United Express Prorate Agreement | CRJ 200 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			24
Term of agreement			120 days
American Agreements | CRJ 200 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			10
American Agreements | CRJ 700 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			37
American Capacity Purchase Agreement | CRJ 700 | ExpressJet
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			12
American Prorate Agreement | CRJ 200 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			6
Term of agreement			120 days
Alaska Capacity Purchase Agreement | CRJ 200 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			4
Alaska Capacity Purchase Agreement | E 175 | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft			23
American
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			65
American | CRJ 200
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			16
American | CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			49
Aircraft in scheduled service
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			595
Aircraft in scheduled service | CRJ 200
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			195
Aircraft in scheduled service | CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			129
Aircraft in scheduled service | CRJ 900
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			52
Aircraft in scheduled service | E 175
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			107
Aircraft in scheduled service | ERJ 135
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			3
Aircraft in scheduled service | ERJ 145
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity			109