Nature of Operations and Summary of Significant Accounting Policies - Agreements (Details)	12 Months Ended
	Dec. 31, 2018 aircraft	Dec. 31, 2016 item
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	628
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	128
CRJ 900
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	41
E 175
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	146
ERJ 145
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	105
Alaska
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	32
Alaska | E 175
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	32
Delta
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	199
Delta | CRJ 200
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	87
Delta | CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	22
Delta | CRJ 900
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	41
Delta | E 175
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	49
Delta Connection Agreement | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Term of agreement	4 years 1 month 6 days
United Express Agreements | Sky West Airlines Inc
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Term of agreement	7 years
American
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	75
American | CRJ 200
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	7
American | CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	68
Aircraft in scheduled service
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	596
Aircraft in scheduled service | CRJ 200
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	200
Aircraft in scheduled service | CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	109
Aircraft in scheduled service | CRJ 900
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	41
Aircraft in scheduled service | E 175
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	146
Aircraft in scheduled service | ERJ 145
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	100