Summary of Significant Accounting Policies - Concentrations of Risk (Details)	12 Months Ended
Dec. 31, 2021 numberOfVendors numberOfLessors employee_group	Dec. 31, 2020	Dec. 31, 2019
Concentration Risk [Line Items]
Number of union-represented employee groups \| employee_group	7
Amount of employees represented by unions	88.00%
Number of lessors with capitalized maintenance deposits \| numberOfLessors	2
Number of vendors with pre-delivery deposits for flight equipment \| numberOfVendors	1
Cost Risk \| Operating Expense \| Aircraft Fuel Cost
Concentration Risk [Line Items]
Concentration risk	26.00%	21.00%	29.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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