XML 48 R37.htm IDEA: XBRL DOCUMENT v3.23.2

Fair Value Measurements (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	$ 964,914	$ 935,844
Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	34,211	88,073
Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	930,703	847,771
Cash Equivalents
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	70,451	147,463
Cash Equivalents | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	34,211	88,073
Cash Equivalents | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	36,240	59,390
Short-Term Investments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	825,167	725,063
Short-Term Investments | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	0	0
Short-Term Investments | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	825,167	725,063
Long Term Investments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	69,296	63,318
Long Term Investments | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	0	0
Long Term Investments | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	69,296	63,318
Money market funds | Cash Equivalents
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	34,211	88,073
Money market funds | Cash Equivalents | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	34,211	88,073
Money market funds | Cash Equivalents | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	0	0
Commercial paper | Cash Equivalents
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	25,946	50,791
Commercial paper | Cash Equivalents | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	0	0
Commercial paper | Cash Equivalents | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	25,946	50,791
Commercial paper | Short-Term Investments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	367,982	421,279
Commercial paper | Short-Term Investments | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	0	0
Commercial paper | Short-Term Investments | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	367,982	421,279
Municipal debt securities | Cash Equivalents
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	7,998	8,599
Municipal debt securities | Cash Equivalents | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	0	0
Municipal debt securities | Cash Equivalents | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	7,998	8,599
Municipal debt securities | Short-Term Investments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	17,486	30,426
Municipal debt securities | Short-Term Investments | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	0	0
Municipal debt securities | Short-Term Investments | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	17,486	30,426
Municipal debt securities | Long Term Investments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	13,460	7,580
Municipal debt securities | Long Term Investments | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	0
Municipal debt securities | Long Term Investments | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	13,460	7,580
US Treasury Bonds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	30,713	0
US Treasury Bonds | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	0	0
US Treasury Bonds | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	30,713	0
Corporate debt securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	22,915	35,688
Corporate debt securities | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	0	0
Corporate debt securities | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	22,915	35,688
Corporate debt securities | Short-Term Investments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	189,954	166,136
Corporate debt securities | Short-Term Investments | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	0	0
Corporate debt securities | Short-Term Investments | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	189,954	166,136
Federal agency debt securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	32,921	20,050
Federal agency debt securities | Cash Equivalents
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	2,296	0
Federal agency debt securities | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	0	0
Federal agency debt securities | Fair Value, Inputs, Level 1 | Cash Equivalents
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	0	0
Federal agency debt securities | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	32,921	20,050
Federal agency debt securities | Fair Value, Inputs, Level 2 | Cash Equivalents
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash Equivalents	2,296	0
Federal agency debt securities | Short-Term Investments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	219,032	107,222
Federal agency debt securities | Short-Term Investments | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	0	0
Federal agency debt securities | Short-Term Investments | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-Sale	$ 219,032	$ 107,222

X

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481830/320-10-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

+ Details

Name:	us-gaap_CashAndCashEquivalentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- 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.

+ Details

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=algt_LongTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_USTreasuryBondSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_USGovernmentCorporationsAndAgenciesSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: