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Impairment (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Special charges			$ 161,600,000	$ 0	$ 0
Long-Lived Assets		$ 0	0
Allegiant Air
Segment Reporting Information [Line Items]
Special charges			5,000,000.0
Sunseeker Resorts
Segment Reporting Information [Line Items]
Special charges	$ 128,900,000	0
Other
Segment Reporting Information [Line Items]
Special charges			26,600,000
Other | Allegiant Nonstop
Segment Reporting Information [Line Items]
Special charges	18,300,000	$ 0
Other | Teesnap
Segment Reporting Information [Line Items]
Special charges	8,300,000
Kingsway Golf
Segment Reporting Information [Line Items]
Special charges	$ 1,100,000
Airbus A320 Aircraft Series | Allegiant Air
Segment Reporting Information [Line Items]
Special charges			$ 0

X

- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228

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X

- Definition

Long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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