3.26.1 html 205 220 1 false 58 0 false 7 false false R1.htm 0000001 - Document - Cover Page Sheet http://www2.allegiantair.com/role/CoverPage Cover Page Cover 1 false false R2.htm 9952151 - Statement - CONSOLIDATED BALANCE SHEETS??(unaudited) Sheet http://www2.allegiantair.com/role/CONSOLIDATEDBALANCESHEETSunaudited CONSOLIDATED BALANCE SHEETS??(unaudited) Statements 2 false false R3.htm 9952152 - Statement - CONSOLIDATED BALANCE SHEETS??(unaudited) (Parenthetical) Sheet http://www2.allegiantair.com/role/CONSOLIDATEDBALANCESHEETSunauditedParenthetical CONSOLIDATED BALANCE SHEETS??(unaudited) (Parenthetical) Statements 3 false false R4.htm 9952153 - Statement - CONSOLIDATED STATEMENTS OF INCOME??(unaudited) Sheet http://www2.allegiantair.com/role/CONSOLIDATEDSTATEMENTSOFINCOMEunaudited CONSOLIDATED STATEMENTS OF INCOME??(unaudited) Statements 4 false false R5.htm 9952154 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME??(unaudited) Sheet http://www2.allegiantair.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEunaudited CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME??(unaudited) Statements 5 false false R6.htm 9952155 - Statement - CONSOLIDATED STATEMENTS OF SHAREHOLDERS??? EQUITY??(unaudited) Sheet http://www2.allegiantair.com/role/CONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITYunaudited CONSOLIDATED STATEMENTS OF SHAREHOLDERS??? EQUITY??(unaudited) Statements 6 false false R7.htm 9952156 - Statement - Consolidated Statements of Cash Flows (Unaudited) Sheet http://www2.allegiantair.com/role/ConsolidatedStatementsofCashFlowsUnaudited Consolidated Statements of Cash Flows (Unaudited) Statements 7 false false R8.htm 9952157 - Disclosure - Summary of Significant Accounting Policies Sheet http://www2.allegiantair.com/role/SummaryofSignificantAccountingPolicies Summary of Significant Accounting Policies Notes 8 false false R9.htm 9952158 - Disclosure - Special Charges Sheet http://www2.allegiantair.com/role/SpecialCharges Special Charges Notes 9 false false R10.htm 9952159 - Disclosure - Revenue Recognition Sheet http://www2.allegiantair.com/role/RevenueRecognition Revenue Recognition Notes 10 false false R11.htm 9952160 - Disclosure - Property and Equipment Sheet http://www2.allegiantair.com/role/PropertyandEquipment Property and Equipment Notes 11 false false R12.htm 9952161 - Disclosure - Long-Term Debt Sheet http://www2.allegiantair.com/role/LongTermDebt Long-Term Debt Notes 12 false false R13.htm 9952162 - Disclosure - Income Taxes Sheet http://www2.allegiantair.com/role/IncomeTaxes Income Taxes Notes 13 false false R14.htm 9952163 - Disclosure - Fair Value Measurements Sheet http://www2.allegiantair.com/role/FairValueMeasurements Fair Value Measurements Notes 14 false false R15.htm 9952164 - Disclosure - Earnings per Share Sheet http://www2.allegiantair.com/role/EarningsperShare Earnings per Share Notes 15 false false R16.htm 9952165 - Disclosure - Contingencies Sheet http://www2.allegiantair.com/role/Contingencies Contingencies Notes 16 false false R17.htm 9952166 - Disclosure - Segments Sheet http://www2.allegiantair.com/role/Segments Segments Notes 17 false false R18.htm 9952167 - Disclosure - Proposed Acquisition of Sun Country Airlines Holdings, Inc. Sheet http://www2.allegiantair.com/role/ProposedAcquisitionofSunCountryAirlinesHoldingsInc Proposed Acquisition of Sun Country Airlines Holdings, Inc. Notes 18 false false R19.htm 9952168 - Disclosure - Subsequent Events Sheet http://www2.allegiantair.com/role/SubsequentEvents Subsequent Events Notes 19 false false R20.htm 995445 - Disclosure - Insider Trading Arrangements Sheet http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements Insider Trading Arrangements Notes 20 false false R21.htm 9955511 - Disclosure - Summary of Significant Accounting Policies - (Policies) Sheet http://www2.allegiantair.com/role/SummaryofSignificantAccountingPoliciesPolicies Summary of Significant Accounting Policies - (Policies) Policies http://www2.allegiantair.com/role/SummaryofSignificantAccountingPolicies 21 false false R22.htm 9955512 - Disclosure - Special Charges (Tables) Sheet http://www2.allegiantair.com/role/SpecialChargesTables Special Charges (Tables) Tables http://www2.allegiantair.com/role/SpecialCharges 22 false false R23.htm 9955513 - Disclosure - Revenue Recognition (Tables) Sheet http://www2.allegiantair.com/role/RevenueRecognitionTables Revenue Recognition (Tables) Tables http://www2.allegiantair.com/role/RevenueRecognition 23 false false R24.htm 9955514 - Disclosure - Property and Equipment (Tables) Sheet http://www2.allegiantair.com/role/PropertyandEquipmentTables Property and Equipment (Tables) Tables http://www2.allegiantair.com/role/PropertyandEquipment 24 false false R25.htm 9955515 - Disclosure - Long-Term Debt (Tables) Sheet http://www2.allegiantair.com/role/LongTermDebtTables Long-Term Debt (Tables) Tables http://www2.allegiantair.com/role/LongTermDebt 25 false false R26.htm 9955516 - Disclosure - Fair Value Measurements (Tables) Sheet http://www2.allegiantair.com/role/FairValueMeasurementsTables Fair Value Measurements (Tables) Tables http://www2.allegiantair.com/role/FairValueMeasurements 26 false false R27.htm 9955517 - Disclosure - Earnings per Share (Tables) Sheet http://www2.allegiantair.com/role/EarningsperShareTables Earnings per Share (Tables) Tables http://www2.allegiantair.com/role/EarningsperShare 27 false false R28.htm 9955518 - Disclosure - Segments (Tables) Sheet http://www2.allegiantair.com/role/SegmentsTables Segments (Tables) Tables http://www2.allegiantair.com/role/Segments 28 false false R29.htm 9955519 - Disclosure - Special Charges - Narrative (Details) Sheet http://www2.allegiantair.com/role/SpecialChargesNarrativeDetails Special Charges - Narrative (Details) Details 29 false false R30.htm 9955520 - Disclosure - Special Charges - Summary of Special Charges (Details) Sheet http://www2.allegiantair.com/role/SpecialChargesSummaryofSpecialChargesDetails Special Charges - Summary of Special Charges (Details) Details 30 false false R31.htm 9955521 - Disclosure - Revenue Recognition - Disaggregation of Revenue (Details) Sheet http://www2.allegiantair.com/role/RevenueRecognitionDisaggregationofRevenueDetails Revenue Recognition - Disaggregation of Revenue (Details) Details 31 false false R32.htm 9955522 - Disclosure - Revenue Recognition - Narrative (Details) Sheet http://www2.allegiantair.com/role/RevenueRecognitionNarrativeDetails Revenue Recognition - Narrative (Details) Details 32 false false R33.htm 9955523 - Disclosure - Revenue Recognition - Contract with Customer, Contract Asset, Contract Liability, and Receivable (Details) Sheet http://www2.allegiantair.com/role/RevenueRecognitionContractwithCustomerContractAssetContractLiabilityandReceivableDetails Revenue Recognition - Contract with Customer, Contract Asset, Contract Liability, and Receivable (Details) Details 33 false false R34.htm 9955524 - Disclosure - Property and Equipment (Details) Sheet http://www2.allegiantair.com/role/PropertyandEquipmentDetails Property and Equipment (Details) Details http://www2.allegiantair.com/role/PropertyandEquipmentTables 34 false false R35.htm 9955525 - Disclosure - Long-Term Debt - Components of Long-Term Debt (Details) Sheet http://www2.allegiantair.com/role/LongTermDebtComponentsofLongTermDebtDetails Long-Term Debt - Components of Long-Term Debt (Details) Details 35 false false R36.htm 9955526 - Disclosure - Long-Term Debt - Summary of Maturities of Long-Term Debt (Details) Sheet http://www2.allegiantair.com/role/LongTermDebtSummaryofMaturitiesofLongTermDebtDetails Long-Term Debt - Summary of Maturities of Long-Term Debt (Details) Details 36 false false R37.htm 9955527 - Disclosure - Long-Term Debt - Narrative (Details) Sheet http://www2.allegiantair.com/role/LongTermDebtNarrativeDetails Long-Term Debt - Narrative (Details) Details 37 false false R38.htm 9955528 - Disclosure - Income Taxes (Details) Sheet http://www2.allegiantair.com/role/IncomeTaxesDetails Income Taxes (Details) Details http://www2.allegiantair.com/role/IncomeTaxes 38 false false R39.htm 9955529 - Disclosure - Fair Value Measurements (Details) Sheet http://www2.allegiantair.com/role/FairValueMeasurementsDetails Fair Value Measurements (Details) Details http://www2.allegiantair.com/role/FairValueMeasurementsTables 39 false false R40.htm 9955530 - Disclosure - Fair Value Measurements Estimated Fair Value of Debt (Details) Sheet http://www2.allegiantair.com/role/FairValueMeasurementsEstimatedFairValueofDebtDetails Fair Value Measurements Estimated Fair Value of Debt (Details) Details 40 false false R41.htm 9955531 - Disclosure - Earnings per Share (Details) Sheet http://www2.allegiantair.com/role/EarningsperShareDetails Earnings per Share (Details) Details http://www2.allegiantair.com/role/EarningsperShareTables 41 false false R42.htm 9955532 - Disclosure - Contingencies (Details) Sheet http://www2.allegiantair.com/role/ContingenciesDetails Contingencies (Details) Details http://www2.allegiantair.com/role/Contingencies 42 false false R43.htm 9955533 - Disclosure - Segments - Narrative (Details) Sheet http://www2.allegiantair.com/role/SegmentsNarrativeDetails Segments - Narrative (Details) Details 43 false false R44.htm 9955534 - Disclosure - Segments - Schedule of Segment Reporting Information, by Segment (Details) Sheet http://www2.allegiantair.com/role/SegmentsScheduleofSegmentReportingInformationbySegmentDetails Segments - Schedule of Segment Reporting Information, by Segment (Details) Details 44 false false R45.htm 9955535 - Disclosure - Proposed Acquisition of Sun Country Airlines Holdings, Inc. - Narrative (Details) Sheet http://www2.allegiantair.com/role/ProposedAcquisitionofSunCountryAirlinesHoldingsIncNarrativeDetails Proposed Acquisition of Sun Country Airlines Holdings, Inc. - Narrative (Details) Details http://www2.allegiantair.com/role/ProposedAcquisitionofSunCountryAirlinesHoldingsInc 45 false false R46.htm 9955536 - Disclosure - Subsequent Events (Details) Sheet http://www2.allegiantair.com/role/SubsequentEventsDetails Subsequent Events (Details) Details http://www2.allegiantair.com/role/SubsequentEvents 46 false false All Reports Book All Reports algt-20260331.htm algt-20260331.xsd algt-20260331_cal.xml algt-20260331_def.xml algt-20260331_lab.xml algt-20260331_pre.xml algt-20260331_g1.jpg http://fasb.org/us-gaap/2026 http://xbrl.sec.gov/dei/2026 http://xbrl.sec.gov/ecd/2026 true true