Nature of Operations and Summary of Significant Accounting Policies - Aircraft Fleet (Details)	12 Months Ended
	Dec. 31, 2020 aircraft
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of daily departures	1,770
Number of aircraft held by entity	601
CRJ 200
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	206
Number of seats on aircraft	50
CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	154
CRJ 700 | Minimum
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of seats on aircraft	65
CRJ 700 | Maximum
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of seats on aircraft	76
CRJ 900
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	48
CRJ 900 | Minimum
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of seats on aircraft	65
CRJ 900 | Maximum
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of seats on aircraft	76
E175
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	193
E175 | Minimum
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of seats on aircraft	65
E175 | Maximum
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of seats on aircraft	76
Delta
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	142
Percentage of aggregate capacity operated	47.10%
Delta | CRJ 200
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	26
Delta | CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	6
Delta | CRJ 900
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	39
Delta | E175
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	71
United
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	213
Percentage of aggregate capacity operated	31.40%
United | CRJ 200
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	104
United | CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	19
United | E175
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	90
American
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	65
Percentage of aggregate capacity operated	14.40%
American | CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	65
Alaska
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	32
Percentage of aggregate capacity operated	7.10%
Alaska | E175
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	32
Aircraft in scheduled service
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	452
Aircraft in scheduled service | CRJ 200
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	130
Aircraft in scheduled service | CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	90
Aircraft in scheduled service | CRJ 900
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	39
Aircraft in scheduled service | E175
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	193
Leased to third parties
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	41
Leased to third parties | CRJ 200
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	2
Leased to third parties | CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	34
Leased to third parties | CRJ 900
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	5
Other
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	108
Other | CRJ 200
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	74
Other | CRJ 700
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	30
Other | CRJ 900
Nature of Operations and Summary of Significant Accounting Policies [Line Items]
Number of aircraft held by entity	4