Allegiant Travel (ALGT) 10-K 1 Mar 22 2021 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2021	Feb. 14, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Entity File Number	001-33166
Entity Registrant Name	Allegiant Travel Co
Entity Central Index Key	0001362468
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Incorporation, State or Country Code	NV
Entity Tax Identification Number	20-4745737
Entity Address, Address Line One	1201 North Town Center Drive
Entity Address, City or Town	Las Vegas,
Entity Address, State or Province	NV
Entity Address, Postal Zip Code	89144
City Area Code	702
Local Phone Number	851-7300
Title of 12(b) Security	Common Stock, $0.001 Par Value
Trading Symbol	ALGT
Security Exchange Name	NASDAQ
Entity Well Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 3
Entity Common Stock, Shares Outstanding		18,112,028
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Documents Incorporated by Reference	Portions of the Proxy Statement to be used in connection with the solicitation of proxies to be voted at the registrant’s annual meeting to be held on June 22, 2022, and to be filed with the Commission subsequent to the date hereof, are incorporated by reference into Part III of this Report on Form 10-K.
Entity Emerging Growth Company	false

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2021
Audit Information [Abstract]
Auditor Name	KPMG LLP
Auditor Location	Dallas, TX
Auditor Firm ID	185

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
CURRENT ASSETS
Cash and cash equivalents	$ 363,378	$ 152,764
Restricted cash	37,323	17,555
Short-term investments	819,478	532,477
Accounts receivable	62,659	192,215
Expendable parts, supplies and fuel, net of reserve of $6,041 and $4,323	27,500	24,006
Prepaid expenses and other current assets	28,073	24,616
TOTAL CURRENT ASSETS	1,338,411	943,633
Property and equipment (including $84,406 and $187,166 from VIEs, Note 7), net of accumulated depreciation of $696,178 and $598,546	2,259,507	2,050,311
Long-term investments	2,231	0
Deferred major maintenance, net of accumulated amortization of $75,177 and $57,022	146,850	127,463
Operating lease right-of-use assets, net	130,087	115,911
Deposits and other assets	113,987	21,607
TOTAL ASSETS:	3,991,073	3,258,925
CURRENT LIABILITIES
Accounts payable	43,566	34,197
Accrued liabilities	19,081	14,313
Current operating lease liabilities	307,453	307,508
Air traffic liability	130,053	217,234
TOTAL CURRENT LIABILITIES	663,045	689,345
LONG-TERM DEBT AND OTHER NONCURRENT LIABILITIES
Long-term debt and finance lease obligations (including $79,127 and $135,683 from VIEs, Note 7), net of current maturities and related costs of $15,664 and $15,926	1,612,486	1,441,777
Deferred income taxes	346,137	301,763
Noncurrent operating lease liabilities	115,067	102,289
Other noncurrent liabilities	30,786	24,388
TOTAL LIABILITIES:	2,767,521	2,559,562
SHAREHOLDERS' EQUITY
Common stock, par value $.001, 100,000,000 shares authorized; 24,763,793 and 23,097,737 shares issued; 18,111,381 and 16,405,565 shares outstanding in 2021 and 2020 respectively	25	23
Treasury shares, at cost, 6,652,412 and 6,692,172 shares in 2021 and 2020, respectively	(638,057)	(646,008)
Additional paid in capital	692,053	329,753
Accumulated other comprehensive gain (loss), net	2,056	(27)
Retained earnings	1,167,475	1,015,622
TOTAL EQUITY:	1,223,552	699,363
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY:	$ 3,991,073	$ 3,258,925

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Expendable parts, supplies and fuel, net of reserve of $6,041 and $4,323	$ 6,041	$ 4,323
Property and equipment (including $84,406 and $187,166 from VIEs, Note 7), net of accumulated depreciation of $696,178 and $598,546	696,178	598,546
PP&E from VIEs	3,991,073	3,258,925
Deferred major maintenance, net of accumulated amortization of $75,177 and $57,022	75,177	57,022
Current maturities of long-term debt and finance lease obligations (including $9,000 and $17,610 from VIEs, Note 7), net of related costs of $385 and $7,527	385	7,527
Current maturities of notes payable, from VIEs	663,045	689,345
Long-term debt and finance lease obligations (including $88,128 and $135,683 from VIEs, Note 7), net of current maturities and related costs of $9,385 and $15,926	$ 9,385	$ 15,926
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	24,763,793	23,097,737
Common stock, shares outstanding	18,111,381	16,405,565
Treasury stock, shares	6,652,412	6,692,172
Current maturities of notes payable, from VIEs	$ 663,045	$ 689,345
Variable Interest Entity, Primary Beneficiary [Member]
Statement of Financial Position [Abstract]
PP&E from VIEs	84,406	187,166
Current maturities of notes payable, from VIEs	9,000	17,610
Long-term debt from VIEs	88,128	135,683
Long-term debt from VIEs	88,128	135,683
Current maturities of notes payable, from VIEs	$ 9,000	$ 17,610

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
OPERATING REVENUES:
Passenger	$ 1,578,436	$ 902,187	$ 1,682,955
Ancillary revenue: [Abstract]
Third party products	86,487	46,482	70,012
Fixed fee contracts	41,184	26,865	65,057
Other	1,803	14,539	22,941
Total operating revenues	1,707,910	990,073	1,840,965
OPERATING EXPENSES:
Salary and benefits	484,573	377,825	450,448
Aircraft fuel	440,235	221,827	427,827
Station operations	243,346	144,771	171,420
Maintenance and repairs	105,943	63,895	91,713
Depreciation and amortization	181,035	176,267	155,852
Sales and marketing	72,742	43,517	78,910
Aircraft lease rental	21,242	9,828	0
Other	83,902	79,277	100,845
Payroll Support Programs grant recognition	(202,181)	(152,448)	0
Special charges	13,998	306,299	0
Total operating expenses	1,444,835	1,271,058	1,477,015
OPERATING INCOME (LOSS)	263,075	(280,985)	363,950
OTHER (INCOME) EXPENSES:
Interest income	(1,814)	(5,509)	(12,523)
Interest expense	68,403	60,493	76,801
Loss on extinguishment of debt	71	1,222	3,677
Special charges	0	26,632	0
Other, net	(205)	(2,756)	(5,252)
Total other expenses	(66,455)	(80,082)	(62,703)
INCOME (LOSS) BEFORE INCOME TAXES	196,620	(361,067)	301,247
INCOME TAX PROVISION (BENEFIT)	44,767	(176,974)	69,130
NET INCOME (LOSS)	$ 151,853	$ (184,093)	$ 232,117
Earnings (loss) per share to common shareholders:
Basic (in dollars per share)	$ 8.69	$ (11.53)	$ 14.27
Diluted (in dollars per share)	$ 8.68	$ (11.53)	$ 14.26
Shares used for computation:
Basic (in shares)	17,212	15,992	16,027
Diluted (in shares)		15,992	16,041
Cash dividends declared per share (in dollars per share)	$ 0	$ 0.70	$ 2.80

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
NET INCOME (LOSS)	$ 151,853	$ (184,093)	$ 232,117
Other comprehensive income (loss):
Change in available for sale securities, net of tax	2,083	(178)	750
Foreign currency translation adjustments	0	53	9
Total other comprehensive income (loss)	2,083	(125)	759
TOTAL COMPREHENSIVE INCOME (LOSS)	$ 153,936	$ (184,218)	$ 232,876

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity Statement - USD ($) $ in Thousands		Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Common StockStock Offering	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Retained EarningsCumulative Effect, Period of Adoption, Adjustment	Treasury Stock	Parent
TOTAL EQUITY		$ 690,321				$ 270,935	$ (661)	$ 1,025,061		$ (605,037)
Common stock, shares outstanding				16,183,000
Common Stock, Value, Issued				$ 23
Exercises of stock options and stock-settled SARs (Shares)				213,000
APIC, Share-based Payment Arrangement, Increase for Cost Recognition											$ 18,998
Stock Repurchased During Period, Shares				(132,000)
Treasury Stock, Value, Acquired, Cost Method										(18,569)	(18,569)
Stock Issued During Period, Shares, Employee Stock Purchase Plans		38,464		39,000
Other Comprehensive Income (Loss), Net of Tax		$ 759					759
Stock Issued During Period, Value, Employee Stock Purchase Plan										6,027	6,027
Dividends, Cash								(45,552)			(45,552)
Unrealized gain on short-term investments, net of tax											759
Net Income		232,117						232,117			232,117
APIC, Share-based Payment Arrangement, Option, Increase for Cost Recognition						18,998
TOTAL EQUITY		$ 883,551	$ (550)			289,933	98	1,211,076	$ (550)	(617,579)
Common stock, shares outstanding				16,303,000
Common Stock, Value, Issued				$ 23
Exercises of stock options and stock-settled SARs (Shares)				262,000
APIC, Share-based Payment Arrangement, Increase for Cost Recognition											38,445
Stock Repurchased During Period, Shares				(217,000)
Treasury Stock, Value, Acquired, Cost Method										(33,773)	(33,773)
Stock Issued During Period, Shares, Employee Stock Purchase Plans		56,866		57,000
Other Comprehensive Income (Loss), Net of Tax		$ (125)					(125)
Stock Issued During Period, Value, Employee Stock Purchase Plan										5,344	5,344
Dividends, Cash	[1]							(11,361)			(11,361)
Unrealized gain on short-term investments, net of tax											(125)
Net Income		(184,093)						(184,093)			(184,093)
Adjustments to Additional Paid in Capital, Warrant Issued						1,375					1,375
APIC, Share-based Payment Arrangement, Option, Increase for Cost Recognition						38,445
TOTAL EQUITY		$ 699,363				329,753	(27)	1,015,622		(646,008)
Common stock, shares outstanding		16,405,565		16,405,000
Common Stock, Value, Issued		$ 23		$ 23
Exercises of stock options and stock-settled SARs (Shares)				113,000
APIC, Share-based Payment Arrangement, Increase for Cost Recognition											27,058
Stock Issued During Period, Shares, Employee Stock Purchase Plans		39,760		40,000
Other Comprehensive Income (Loss), Net of Tax		$ 2,083					2,083
Stock Issued During Period, Value, Employee Stock Purchase Plan										7,951	7,951
Unrealized gain on short-term investments, net of tax											2,083
Net Income		151,853						151,853			151,853
Adjustments to Additional Paid in Capital, Warrant Issued						105					105
APIC, Share-based Payment Arrangement, Option, Increase for Cost Recognition						27,058
Stock Issued During Period, Value, New Issues				$ 2		335,137					$ 335,139
Stock Issued During Period, Shares, New Issues					1,553,000
TOTAL EQUITY		$ 1,223,552				$ 692,053	$ 2,056	$ 1,167,475		$ (638,057)
Common stock, shares outstanding		18,111,381		18,111,000
Common Stock, Value, Issued		$ 25		$ 25
[1]	Dividend declared and paid in the first quarter of 2020 prior to the onset of the pandemic. As a part of accepting benefits from the Treasury under payroll support programs, the Company has agreed not to pay cash dividends through September 30, 2022.

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parentheticals) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Stockholders' Equity [Abstract]
Cash dividends (per Share)	$ 0	$ 0.70	$ 2.80

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
OPERATING ACTIVITIES:
Net income (loss)		$ 151,853	$ (184,093)	$ 232,117
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		181,035	176,267	155,852
Gain on aircraft and other equipment disposals		(3,052)	(1,811)	(8,475)
Special charges		13,998	292,790	0
Share-based compensation expense		16,127	19,287	18,226
Deferred income taxes		43,761	69,344	68,466
Other adjustments		14,777	19,136	5,521
Changes in certain assets and liabilities:
Accounts receivable		(14,717)	4,390	10,498
Tax receivable		143,624	(164,585)	0
Prepaid expenses		(4,026)	10,224	(5,483)
Accounts payable		10,402	7,016	(2,103)
Accrued liabilities		48,060	(26,386)	21,331
Air traffic liability		(55)	57,558	37,720
Deferred major maintenance		(59,747)	(40,352)	(81,133)
Other assets/liabilities		(3,847)	(4,163)	(10,327)
Net cash provided by operating activities		538,193	234,622	442,210
INVESTING ACTIVITIES:
Purchase of investment securities		(1,248,575)	(686,600)	(436,237)
Proceeds from maturities of investment securities		954,970	504,600	454,813
Purchase of property and equipment, including capitalized interest		(255,537)	(281,159)	(506,845)
Proceeds from sale-leaseback transactions		0	87,580	0
Payments to Acquire Notes Receivable		(50,000)	0	0
Other investing activities		5,864	9,888	11,806
Net cash used in investing activities		(593,278)	(365,691)	(476,463)
FINANCING ACTIVITIES:
Proceeds from issuance of common stock		335,139	0	0
Cash dividends paid to shareholders	[1]	0	(11,361)	(45,552)
Proceeds from the issuance of debt and finance lease obligations		281,657	427,987	874,936
Repurchase of common stock		0	(33,773)	(18,569)
Principal payments on debt and finance lease obligations		(301,096)	(217,766)	(705,763)
Debt issuance costs		(8,287)	(7,203)	(33,333)
Other financing activities		(21,946)	6,719	3,408
Net cash provided by financing activities		285,467	164,603	75,127
NET CHANGE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH		230,382	33,534	40,874
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT BEGINNING OF PERIOD		170,319	136,785	95,911
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT END OF PERIOD		400,701	170,319	136,785
CASH PAYMENTS/(RECEIPTS) FOR:
Interest paid, net of amount capitalized		43,511	48,002	65,152
Income tax refunds		(128,540)	(95,229)	(2,157)
SUPPLEMENTAL DISCLOSURE OF NONCASH TRANSACTIONS
Right-of-use (ROU) assets acquired		33,260	115,082	2,510
Purchases of property and equipment in accrued liabilities		17,671	19,294	25,830
Flight equipment acquired under finance leases		$ 101,340	$ 27,765	$ 0
[1]	Dividend declared and paid in the first quarter of 2020 prior to the onset of the pandemic. As a part of accepting benefits from the Treasury under payroll support programs, the Company has agreed not to pay cash dividends through September 30, 2022.

Organization and Business of Co

Organization and Business of Company (Notes)	12 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Business of Company	Organization and Business of Company Allegiant Travel Company (the “Company”) is a leisure travel company focused on providing travel services and products to residents of under-served cities in the United States. The Company operates a low-cost, low utilization passenger airline which sells air transportation both on a stand-alone basis and bundled with the sale of ancillary air-related and third party services and products. The Company also provides air transportation under fixed fee flying arrangements, generates other ancillary revenues, and operates non-airline related entities which include the development of Sunseeker Resort and related golf course. Previously, the Company also operated Allegiant Nonstop family entertainment centers and the Teesnap golf course management solution. Scheduled service and fixed fee air transportation services have similar operating margins, economic characteristics, and production processes (check-in, baggage handling and flight services) which target the same class of customers, and are subject to the same regulatory environment. As a result, the Company believes its airline activities operate under one reportable segment and does not separately track expenses for scheduled service and fixed fee air transportation services. The Company's non-airline related entities represent separate reportable segments and include Sunseeker Resort, and other non-airline activities. Refer to Note 16 for additional information.

Unusual or Infrequently Occurri

Unusual or Infrequently Occurring Items	12 Months Ended
	Dec. 31, 2021
Unusual or Infrequent Items, or Both [Abstract]
Unusual or Infrequent Items, or Both, Disclosure	Impact of the COVID-19 Pandemic The rapid spread of COVID-19 and the related government restrictions, social distancing measures, and consumer fears have impacted flight loads, resulted in unprecedented cancellations of bookings and substantially reduced demand for new bookings throughout the airline industry. Starting in March 2020, the Company and the airline industry experienced a severe reduction in air travel which continued into 2021 to some extent. Demand in the foreseeable future will continue to be affected by fluctuations in COVID-19 cases, variants, hospitalizations, deaths, treatment efficacy and the availability of vaccines. The Company is continuously reevaluating flight schedules and adjusting capacity based on demand trends. During 2020 and 2021, Congress enacted various legislation which provided support for the airline industry. This included The Coronavirus Aid, Relief and Economic Security Act (the "CARES Act") enacted in March 2020, the Consolidated Appropriations Act, 2021 enacted in December 2020 (the “Payroll Support Program Extension”) and the American Rescue Plan Act enacted in March 2021) (the “ARPA”). On January 15, 2021, the Company through its airline operating subsidiary Allegiant Air, LLC entered into a Payroll Support Program Extension Agreement (the “PSP2”) with the Treasury and received $91.8 million under the Payroll Support Program Extension. In April 2021, the Company received $13.8 million in additional funds related to the PSP2 which included a loan of $1.7 million. In consideration for these additional funds, the Company issued additional warrants ( the "PSP2 Warrants") to the Treasury to acquire 924 shares of common stock at a price of $179.23 per share (based on the price of the Company's common stock on the Nasdaq Global Select Market on December 24, 2020). The funds under PSP2 were used exclusively for wages, salaries and benefits. In April 2021, the Company through its airline operating subsidiary Allegiant Air, LLC entered into a Payroll Support Program 3 Agreement (the "PSP3") with the Treasury under the ARPA and received a total of $98.4 million. The funds were used exclusively for wages, salaries and benefits. As of December 31, 2021, all Payroll Support Program funds have been fully utilized. Special Charges The table below summarizes special charges recorded during 2021 and 2020. For the Year Ended December 31, 2021 Airline Sunseeker Resort Other non-airline Total Operating $ 13,453 $ — $ 545 $ 13,998 Non-operating — — — — Total special charges $ 13,453 $ — $ 545 $ 13,998 Additional detail for the $14.0 million of total special charges for 2021 appears below: • $2.5 million resulting from the accelerated retirement of two airframes and three engines • $0.5 million impairment loss on a building in Chesterfield, Missouri associated with the Allegiant Nonstop family entertainment line of business. • $10.9 million related to the acceleration of certain existing stock awards. For the Year Ended December 31, 2020 Airline Sunseeker Resort Other non-airline Total Operating $ 141,713 $ 137,994 $ 26,592 $ 306,299 Non-operating — 26,632 — 26,632 Total special charges $ 141,713 $ 164,626 $ 26,592 $ 332,931 Additional detail for the $332.9 million of total special charges (operating and non-operating) for 2020 appears below: • $161.6 million in impairment charges primarily in our non-airline subsidiaries • $98.0 million resulting from the accelerated retirement of eight airframes and five engines, loss on sale leaseback transactions of eight aircraft, and write-offs of other aircraft related assets • $35.1 million for additional salaries and benefits expense in relation to the elimination of positions as well as other non-recurring compensation expense associated with the acceleration of certain existing stock awards • $26.6 million related to termination of a loan agreement intended to finance the development of Sunseeker Resort-Charlotte Harbor • $5.0 million related to suspension of construction at Sunseeker Resort • $6.6 million write-down on various non-aircraft assets and other various expenses

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements include the accounts of Allegiant Travel Company and its majority-owned operating subsidiaries. The Company's investments in unconsolidated affiliates, which are 50 percent or less owned, are accounted for under the equity or cost method. All intercompany balances and transactions have been eliminated. The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Actual results could differ from these estimates. Cash and Cash Equivalents Cash and cash equivalents include investments and interest bearing instruments with original maturities of three months or less. Such investments are carried at cost which approximates fair value. Restricted Cash Restricted cash represents escrowed funds under fixed fee contracts, and cash collateral held against letters of credit required by hotel properties for guaranteed room availability, airports and certain other parties. Accounts Receivable Accounts receivable are carried at face amount which approximates fair value. In addition to income tax receivables, the accounts receivable consist primarily of amounts due from credit card companies associated with the sale of tickets for future travel. These receivables are short-term and generally settle within a few days of sale. There are also receivables related to commission amounts due from Enterprise Holdings Inc. based on terms in the rental car provider agreement and amounts due related to fixed fee charter agreements. If deemed necessary, the Company records charges to its allowance for doubtful accounts for amounts not expected to be collected, for which the balance was immaterial for all years presented. Short-term and Long-term Investments The Company’s investments in marketable securities are classified as available-for-sale and are reported at fair value with the net unrealized gain or (loss) reported as a component of accumulated other comprehensive income (loss) in shareholders’ equity. For investments in an unrealized loss position, the Company determines whether a credit loss exists by considering information about the collectability of the instrument and current market conditions. There have been no credit losses in the years presented. Investment securities with original maturities of three months or less are classified as cash equivalents. Investment securities with original maturities greater than three months are classified as either short-term investments or long-term investments based on the maturity date in relation to the balance sheet date. Short-term investments have a maturity date less than or equal to one year from the balance sheet date, and long-term investments have a maturity date greater than one year from the balance sheet date. The amortized cost of investment securities sold is determined by the specific identification method with any realized gains or losses reflected in other (income) expense. The Company had minimal realized losses during the years ended December 31, 2021, 2020, and 2019. The Company believes unrealized losses related to debt securities are not other-than-temporary and does not intend to sell these securities prior to amortized cost recoverability. The Company attempts to minimize its concentration risk with regard to its cash, cash equivalents, and investment portfolio. This is accomplished by diversifying and limiting amounts among different counterparties, the type of investment, and the amount invested in any individual security, commercial paper, or money market fund. Expendable Parts, Supplies and Fuel, Net Expendable parts, supplies and fuel inventories are valued at cost using the first-in, first-out method. Such inventories are charged to expense as they are used in operations. An obsolescence allowance for expendable parts and supplies is based on salvage values and the average remaining useful life of the Airbus fleet. The obsolescence allowance for expendable parts and supplies was $6.0 million and $4.3 million at December 31, 2021 and 2020, respectively. Rotable aircraft parts inventories are included in property and equipment. Deposits and Other Assets Deposits and Other Assets consist primarily of airport deposits, aircraft purchase deposits, deposits as required by the construction loan agreement and a note receivable to the counter-party in the Company’s joint venture alliance. The Company also had outstanding receivables from third parties as of December 31, 2021 and 2020, of which $12.4 million and $10.9 million respectively, was due more than one year after the balance sheet date. Operating Lease Right-of-Use Asset and Liability The Company determines if an arrangement is a lease at inception and has lease agreements for aircraft, office facilities, office equipment, certain airport and terminal facilities, and other space and assets with non-cancelable lease terms. Certain real estate and property leases, aircraft leases, and various other operating leases are measured on the balance sheet with a lease liability and right-of-use ("ROU") asset. Airport terminal leases mostly include variable lease payments outside of those based on a fixed index, and are therefore excluded from consideration. ROU assets represent the Company's right to use an underlying asset for the lease term, and lease liabilities represent the obligation to make scheduled lease payments. ROU assets and liabilities are recognized on the lease commencement date based on the present value of lease payments over the lease term. The present value of lease payments is calculated using an estimated incremental borrowing rate at lease commencement, which takes into consideration recent debt issuances as well as other applicable market data available. Lease payments include fixed payments, variable payments based on an index or rate, reasonably certain purchase options, termination penalties, and others as required by the Accounting Standards (ASU) 2016-02, Leases (Topic 842). Lease payments do not include variable lease payments other than those that depend on an index or rate, any guarantee by the lessee of the lessor’s debt, or any amount allocated to non-lease components. Lease terms include options to extend when it is reasonably certain that the option will be exercised. Leases with a term of 12 months or less are not recorded on the balance sheet. Additionally, lease and non-lease components are accounted for as a single lease component for real estate agreements. Property and Equipment Property and equipment are recorded at cost and depreciated using the straight-line method over their estimated useful lives less any estimated salvage value. Property under finance leases and related obligations are initially recorded at an amount equal to the present value of future minimum lease payments computed on the basis of the Company’s incremental borrowing rate, and depreciation is recorded on a straight-line basis and is included within depreciation and amortization expense. The estimated useful lives of the principal asset classes are shown below. Aircraft, engines and related rotable parts 10-25 years Buildings and leasehold improvements 10-25 years Equipment 3-10 years Computer hardware and software 3-10 years In estimating the useful lives and residual values of aircraft, the Company primarily relies upon actual experience with the same or similar aircraft types, current and projected future market information, and input from other industry sources. Subsequent revisions to these estimates could be caused by changing market prices of the Company’s aircraft, changes in utilization of the aircraft, and other fleet events. Changes in the estimate for useful lives or residual values of the Company’s property and equipment could result in changes in depreciation expense. Interest is capitalized using the Company’s weighted average borrowing rate and depreciated over the estimated useful life of the related asset(s) acquired/developed. Capitalized interest for the years ended December 31, 2021, 2020 and 2019 was $0.2 million, $4.1 million and $4.5 million, respectively. Software Capitalization The Company capitalizes certain internal and external costs related to the acquisition and development of computer software during the application development stage of projects. The Company amortizes these capitalized costs using the straight-line method over the estimated useful life of the software, which typically ranges from three Aircraft Maintenance and Repair Costs The Company accounts for all non-major maintenance and repair costs incurred for its Airbus fleet under the direct expense method. Under this method, maintenance and repair costs for aircraft are charged to operating expenses as incurred. Maintenance and repair costs includes all parts, materials, and line maintenance activities required to maintain the Company's fleet. The Company accounts for major maintenance costs of its Airbus airframes and the related CFM engines using the deferral method. Under this method, the Company capitalizes the cost of major maintenance events, which are amortized as a component of depreciation and amortization expense, over the estimated period until the next scheduled major maintenance event. During 2021 and 2020, the Company capitalized $23.3 million and $12.8 million of major maintenance costs for engines with associated amortization expense of $21.0 million and $17.6 million respectively. During 2021 and 2020, the Company capitalized $39.0 million and $22.6 million of major maintenance costs for airframes. Amortization expense related to major maintenance costs was $21.1 million, $19.9 million and $14.9 million for the years ended December 31, 2021, 2020 and 2019 respectively. Measurement of Impairment of Long-Lived Assets The Company records impairment losses on long-lived assets used in operations, consisting principally of property and equipment, when events or changes in circumstances indicate, in management’s judgment, that the assets might be impaired, and the undiscounted future cash flows estimated to be generated by those assets are less than the carrying amount of those assets. In making these determinations, the Company utilizes certain assumptions, including, but not limited to: (i) estimated fair value of the assets; and (ii) estimated future cash flows expected to be generated by these assets, which are based on additional assumptions such as asset utilization, length of service for which the asset will be used in operations, and estimated salvage values. For the year ended December 31, 2019, the Company did not incur any impairment losses. For the year ended December 31, 2020, the Company recorded a $161.6 million impairment as a result of COVID-19. For the year ended December 31, 2021, the Company recorded a $0.5 million impairment loss on a building in Chesterfield, Missouri associated with the Allegiant Nonstop family entertainment line of business. Revenue Recognition Passenger revenue Passenger revenue includes scheduled service revenue, ancillary air-related charges, and travel point redemptions from the co-branded Allegiant World Mastercard® credit card and the Company's non-card loyalty program. Scheduled service revenue consists of ticket revenue generated from nonstop flights in the Company’s route network, recognized either when the transportation is provided or when ticket voucher breakage occurs. Nonrefundable scheduled itineraries expire on the date of the intended flight, unless the date is extended by notification from the customer in advance. Itineraries sold for transportation not yet used, as well as unexpired credits, are included in air traffic liability. Ancillary air-related charges include various services and products related to the flight such as baggage fees, the use of the Company’s website to purchase scheduled service transportation, advance seat assignments, and other services which are not included in the base ticket price. Revenues from air-related charges are recognized when the transportation is provided. If a customer cancels a flight, a voucher may be issued for a future flight, at which time the associated revenue is recognized upon completion of the future flight. Additionally, the Company estimates the value of vouchers that will expire unused and recognizes such revenue at the time of issuance. Various taxes and fees, assessed on the sale of tickets to customers, are collected by the Company serving as an agent, and remitted to taxing authorities. These taxes and fees are not included as revenue in the Company’s consolidated statements of income and are recorded as a liability until remitted to the appropriate taxing authority. Revenue from travel point redemptions from the co-branded credit card and the Loyalty program are described in the Affinity Credit Card Program and Allways Rewards Loyalty Program sections below. Third party products revenue Ancillary third party products revenue is generated from the sale of hotel rooms, rental cars and ticket attractions, as well as marketing revenue associated with the co-branded credit card. Revenue from the sale of third party products is recognized at the time the product is utilized, such as the time a purchased hotel room is occupied. Revenue from the sale of third party products is recorded net of amounts paid to wholesale providers, travel agent commissions, and transaction costs. Pursuant to the co-brand arrangement with Bank of America, the Company has various performance obligations which are collectively referred to as the marketing component. These obligations consist of use of the Company’s brand and access to its member lists, and certain other advertising and marketing elements. The marketing component is recorded as third party products revenue in the period in which points are awarded to the credit card holders. Fixed fee contract revenue Fixed fee contract revenue consists of agreements to provide charter service on a year-round and ad hoc basis. Fixed fee contract revenue is recognized when the transportation is provided. Other revenue Other revenue is generated from non-airline activities as well as leasing aircraft and engines. Lease revenue is recognized ratably over the lease term. Affinity Credit Card Program The Allegiant World Mastercard® is issued by Bank of America through which arrangement points are sold and consideration is received under an agreement that expires in 2029. Under this arrangement, the Company identified the following deliverables: travel points to be awarded (the travel component), use of the Company’s brand and access to its member lists, and certain other advertising and marketing elements (collectively the marketing component). Each of these deliverables is accounted for separately and allocation of the consideration from the agreement is determined based on the relative selling price of each deliverable. The Company applied a level of management judgment and estimation in determining the best estimate of selling price for each deliverable by considering multiple inputs and methods including, but not limited to, the redemption value of points awarded, discounted cash flows, brand value, volume discounts, published selling prices, number of points to be awarded and number of points expected to be redeemed. Revenue from the travel component is deferred based on its relative selling price and is recognized into passenger revenue when the points are redeemed by cardholders and transportation is provided. Revenue from the marketing component is considered earned in the period in which points are sold and is therefore recognized into third party products revenue in the same period. Allways Rewards Loyalty Program Allegiant’s Allways Rewards Loyalty Program enables program Members to earn points for every dollar they spend on the Company’s website. Under the program, which launched in August 2021, Members continue to accumulate points until the time they decide to redeem them. In addition to opportunities to redeem points for flights, lodging and rental cars, the program leverages Allegiant's partnerships to offer additional rewards to Members, including sports and live music event tickets and exclusive experiences. Members can also earn points by using their Allegiant World Mastercard®. Under Allways Rewards, Members receive one point for every dollar spent at Allegiant.com, and two points per $1 for spending over $500 (excluding taxes and fees). The Company utilizes the deferred revenue method of accounting for points earned through the program based on the stand alone selling price and revenue is recognized when points are redeemed and the underlying service has been provided. Advertising Costs Advertising costs are charged to expense in the period incurred. Advertising expense was $31.3 million, $12.4 million and $29.1 million for the years ended December 31, 2021, 2020 and 2019, respectively. In 2019, the Company entered into a naming rights agreement with the Raiders of the National Football League for the professional football stadium in Las Vegas which opened in 2020. Prepayments and other associated advertising expenses began in mid-2020 and will continue through the term of this agreement. Earnings per Share Basic and diluted earnings per share are computed pursuant to the two-class method as opposed to the treasury method. Under the two-class method, the Company attributes net income to two classes, common stock and unvested restricted stock awards. Unvested restricted stock awards granted to employees under the Company’s Long-Term Incentive Plan are considered participating securities because they receive non-forfeitable rights to cash dividends at the same rate as common stock. Diluted net income per share is calculated using the more dilutive of two methods. Under both methods, the exercise of employee stock options is assumed using the treasury stock method. The assumption of vesting of restricted stock, however, differs as described below: 1. Assume vesting of restricted stock using the treasury stock method. 2. Assume unvested restricted stock awards are not vested, and allocate earnings to common shares and unvested restricted stock awards using the two-class method. For the years ended December 31, 2021 and 2019, the second method above was used in the computation because it was more dilutive than the first method. Given the loss position in 2020, both methods yield the same result. The following table sets forth the computation of net income (loss) per share on a basic and diluted basis for the periods indicated: Year ended December 31, (in thousands, except per share data) 2021 2020 2019 Basic: Net income (loss) $ 151,853 $ (184,093) $ 232,117 Less income allocated to participating securities (2,218) (236) (3,413) Net income (loss) attributable to common stock $ 149,635 $ (184,329) $ 228,704 Earnings (loss) per share, basic $ 8.69 $ (11.53) $ 14.27 Weighted-average shares outstanding 17,212 15,992 16,027 Diluted: Net income (loss) $ 151,853 $ (184,093) $ 232,117 Less income allocated to participating securities (2,215) (236) (3,410) Net income (loss) attributable to common stock $ 149,638 $ (184,329) $ 228,707 Earnings (loss) per share, diluted $ 8.68 $ (11.53) $ 14.26 Weighted-average shares outstanding 17,212 15,992 16,027 Dilutive effect of stock options and restricted stock 145 — 51 Adjusted weighted-average shares outstanding under treasury stock method 17,357 15,992 16,078 Participating securities excluded under two-class method (126) — (37) Adjusted weighted-average shares outstanding under two-class method 17,231 15,992 16,041 Stock awards outstanding of 815, 24,004, and 19,928 shares (not in thousands) as of December 31, 2021, 2020, and 2019, respectively, were excluded from the computation of diluted earnings per share as they were antidilutive. Share-Based Compensation The Company accounts for share-based compensation in accordance with accounting standards which require the compensation cost related to share-based payment transactions be recognized in the Company’s consolidated statements of income. The share-based cost is measured based on grant date fair value. The Company’s share-based employee compensation plan is more fully discussed in Note 13. Income Taxes The Company recognizes deferred income taxes based on the asset and liability method required by accounting standards. Deferred tax assets and liabilities are determined based on the timing differences between book basis for financial reporting purposes and tax basis of the asset and liability and measured using the enacted tax rates and provisions of the enacted tax law. A valuation allowance for deferred tax assets is provided if it is more likely than not that some portion or all of the deferred tax assets will not be realized. The Company determines the net non-current deferred tax assets or liabilities separately for federal, state, foreign and other local jurisdictions. The Company’s income tax returns are subject to examination by the Internal Revenue Service (“IRS”) and other tax authorities in the jurisdictions where the Company operates. The Company assesses potentially unfavorable outcomes of such examinations based on the criteria set forth in uncertain tax position accounting standards. The accounting standards prescribe a minimum recognition threshold a tax position is required to meet before being recognized in the financial statements. Accounting standards for income taxes utilize a two-step approach for evaluating tax positions. Recognition (Step I) occurs when the Company concludes that a tax position, based on its technical merits, is more likely than not to be sustained upon examination. Measurement (Step II) is only addressed if the position is deemed to be more likely than not to be sustained. Under Step II, the tax benefit is measured as the largest amount of benefit that is greater than 50 percent likely of being realized upon settlement. The tax positions failing to qualify for initial recognition are recognized in the first subsequent interim period they meet the “more likely than not” standard. If it is subsequently determined that a previously recognized tax position no longer meets the “more likely than not” standard, it is required that the tax position be derecognized. As applicable, the Company will recognize accrued penalties and interest related to unrecognized tax benefits in the provision for income taxes. Recent Accounting Pronouncements On June 16, 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments. The standard requires the use of an “expected loss” model on certain types of financial instruments. The standard also amends the impairment model for available-for-sale debt securities and requires estimated credit losses to be recorded as allowances instead of reductions to amortized cost of the securities. The Company adopted this accounting standard prospectively as of January 1, 2020, and it did not have a significant impact on its consolidated financial statements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. This standard is intended to simplify various aspects related to accounting for income taxes and is effective for fiscal years beginning after December 15, 2020, including interim periods therein, and early adoption is permitted. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application of Topic 740. The Company adopted ASU 2019-12 in the first quarter of 2021 and its adoption did not have a material effect on the Company's consolidated financial statements.

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition Passenger revenue Passenger revenue is the most significant category in our reported operating revenues, as outlined below: Year Ended December 31, (in thousands) 2021 2020 2019 Scheduled service $ 769,371 $ 435,668 $ 897,631 Ancillary air-related charges 788,064 453,545 770,206 Loyalty redemptions 21,001 12,974 15,118 Total passenger revenue $ 1,578,436 $ 902,187 $ 1,682,955 Sales of passenger tickets not yet flown are recorded in air traffic liability. Passenger revenue is recognized when transportation is provided. As of December 31, 2021, the air traffic liability balance was $307.5 million, of which approximately $240.5 million was related to forward bookings, with the remaining $67.0 million related to credit vouchers for future travel. The normal contract term of passenger tickets is 12 months and passenger revenue associated with future travel will principally be recognized within this time frame. Of the $307.5 million that was recorded in the air traffic liability balance at December 31, 2020, 88.0 percent was recognized into passenger revenue during the 12 months ended December 31, 2021. In 2020, the Company announced that credit vouchers issued for canceled travel beginning in January 2020 would have an extended expiration date of two years from the original booking date. This policy continued for credit vouchers issued through June 30, 2021. Estimates of passenger revenue to be recognized from air traffic liability for credit voucher breakage may be subject to variability and differ from historical experience due to the change in contract duration and uncertainty regarding demand for future air travel. Effective July 1, 2021, vouchers issued have an expiration date of one year from the original booking date. The Company periodically evaluates the estimated amount of credit vouchers expected to expire unused and any adjustment is removed from air traffic liability and included in passenger revenue in the period in which the evaluation is complete. Loyalty redemptions In relation to the travel component of the co-branded credit card contract with Bank of America, the Company has a performance obligation to provide cardholders with points to be used for future travel award redemptions. Therefore, consideration received from Bank of America related to the travel component is deferred based on its relative selling price and is recognized into passenger revenue when the points are redeemed and the transportation is provided. The following table presents the activity of the co-brand point liability as of the dates indicated: Year Ended December 31, (in thousands) 2021 2020 Balance at January 1 $ 21,841 $ 15,613 Points awarded 39,650 19,202 Points redeemed (21,001) (12,974) Balance at December 31 $ 40,490 $ 21,841 As of December 31, 2021 and 2020, $17.8 million and $10.9 million, respectively, of the current points liability is reflected in accrued liabilities and represents the current estimate of revenue to be recognized in the next 12 months based on historical trends, with the remaining balance reflected in other noncurrent liabilities and expected to be recognized into revenue in periods thereafter.

Accrued Liabilities (Notes)

Accrued Liabilities (Notes)	12 Months Ended
	Dec. 31, 2021
Payables and Accruals [Abstract]
Accounts Payable and Accrued Liabilities Disclosure	Accrued Liabilities Accrued liabilities consisted of the following: As of December 31, (in thousands) 2021 2020 Salaries, wages and benefits $ 38,313 $ 21,878 Sunseeker Resort development 12,241 14,084 Maintenance and repairs 11,718 12,847 Loyalty program liability 17,787 10,929 Station expenses 21,297 10,526 Property taxes 7,853 9,042 Interest 10,519 6,560 Passenger taxes and fees 14,324 4,686 Advertising accruals 1,863 890 Other accruals 26,977 24,651 Total accrued liabilities $ 162,892 $ 116,093

Lease (Notes)

Lease (Notes)	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Lessee, Operating Leases [Text Block]	Leases The Company had 15 aircraft under finance leases and 17 aircraft under operating leases as of December 31, 2021 with remaining terms through 2032. Lease Costs The components of lease costs recognized on the statements of income were as follows: Year Ended December 31, (in thousands) Classification on the Statements of Income 2021 2020 Finance lease costs: Amortization of assets Depreciation and amortization $ 13,274 $ 6,631 Interest on lease liabilities Interest expense 11,168 5,335 Operating lease cost Aircraft lease rentals; Station operations; Maintenance and repairs; Other operating expense 22,697 12,616 Variable lease cost Station operations; Maintenance and repairs; Other operating expense 2,565 3,560 Total lease cost $ 49,704 $ 28,142 Lease position as of December 31, 2021 The table below presents the lease-related assets and liabilities recorded on the balance sheet. As of December 31, (in thousands) Classification on the Balance Sheet 2021 2020 Assets Operating lease assets Operating lease right-of-use assets, net $ 130,087 $ 115,911 Finance lease assets Property and equipment, net 338,469 133,175 Total lease assets $ 468,556 $ 249,086 Liabilities Current Operating Current operating lease liabilities $ 19,081 $ 14,313 Finance Current maturities of long-term debt and finance lease obligations 16,960 9,767 Noncurrent Operating Noncurrent operating lease liabilities 115,067 102,289 Finance Long-term debt and finance lease obligations 301,532 117,060 Total lease liabilities $ 452,640 $ 243,429 Weighted-average remaining lease term Operating leases 7.7 years 8.3 years Finance leases 7.8 years 7.6 years Weighted-average discount rate Operating leases 5.4 % 5.4 % Finance leases 5.2 % 5.0 % Sale-Leaseback Transactions In March 2021, the Company entered into a sale-leaseback transaction involving three aircraft and generating $105.0 million of proceeds. The lease was classified as a finance lease and as a result, the transaction did not qualify as a sale. The aircraft were not removed from property and equipment in the Company's balance sheet and the Company recorded a financial liability in the amount of $105.0 million. The proceeds from this transaction are treated as cash inflows from finance lease obligations and reported in financing activities on the statement of cash flows. During the year ended December 31, 2020, the Company entered into sale-leaseback transactions involving eight total aircraft. The transactions qualified as sales, and generated $87.6 million of proceeds. As a result of the sales, the aircraft were removed from property and equipment in the Company's balance sheet, resulting in a $53.2 million loss on the sales. The loss is reflected within operating special charges on the statement of income since the Company would not likely have completed the transactions absent cash conservation efforts as a result of COVID-19. The leased aircraft were subsequently recorded within operating lease right-of-use assets, with the related lease liabilities recorded within current and noncurrent operating lease liabilities on the balance sheet. The proceeds from the sales of aircraft in these transactions are treated as cash inflows from investing activities on the statement of cash flows. Other Information The table below presents supplemental cash flow information related to leases during the year ended December 31. Year Ended December 31, (in thousands) 2021 2020 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows for operating leases $ 18,987 $ 13,102 Operating cash flows for finance leases 10,697 5,335 Financing cash flows for finance leases 14,675 15,908 Maturities of Lease Liabilities The table below indicates the future minimum payments of lease liabilities as of December 31, 2021. (in thousands) Operating Leases Finance Leases 2022 $ 25,781 $ 32,822 2023 25,618 44,813 2024 25,299 29,268 2025 23,158 29,268 2026 13,184 28,968 Thereafter 49,317 250,141 Total lease payments 162,357 415,280 Less imputed interest (28,209) (96,788) Total lease obligations 134,148 318,492 Less current obligations (19,081) (16,960) Long-term lease obligations $ 115,067 $ 301,532
Sale Leaseback Transactions	Sale-Leaseback Transactions In March 2021, the Company entered into a sale-leaseback transaction involving three aircraft and generating $105.0 million of proceeds. The lease was classified as a finance lease and as a result, the transaction did not qualify as a sale. The aircraft were not removed from property and equipment in the Company's balance sheet and the Company recorded a financial liability in the amount of $105.0 million. The proceeds from this transaction are treated as cash inflows from finance lease obligations and reported in financing activities on the statement of cash flows. During the year ended December 31, 2020, the Company entered into sale-leaseback transactions involving eight total aircraft. The transactions qualified as sales, and generated $87.6 million of proceeds. As a result of the sales, the aircraft were removed from property and equipment in the Company's balance sheet, resulting in a $53.2 million loss on the sales. The loss is reflected within operating special charges on the statement of income since the Company would not likely have completed the transactions absent cash conservation efforts as a result of COVID-19. The leased aircraft were subsequently recorded within operating lease right-of-use assets, with the related lease liabilities recorded within current and noncurrent operating lease liabilities on the balance sheet. The proceeds from the sales of aircraft in these transactions are treated as cash inflows from investing activities on the statement of cash flows.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Stockholders' Equity	Shareholders’ Equity The Company is authorized by its Board of Directors to acquire the Company’s stock through open market purchases under its share repurchase program. As repurchase authority is exhausted, the Board of Directors has, to date, authorized additional expenditures for share repurchases. The Company suspended stock repurchases upon the onset of the pandemic and as part of accepting benefits from the Treasury under the Payroll Support Programs, the Company has agreed not to repurchase stock through September 30, 2022. Share repurchases consisted of the following during the periods indicated: Year Ended December 31, 2021 2020 2019 Shares repurchased (1) — 197,570 103,943 Average price per share $ — $ 155.14 $ 141.64 Total (in thousands) $ — $ 30,651 $ 14,723 (1) Share amounts shown above include only open market repurchases and do not include shares withheld from employees for tax withholding obligations related to restricted stock vestings, which were 19,001 and 27,700 shares for 2020 and 2019, respectively. Cash dividends declared by the Board and paid by the Company consisted of the following during the periods indicated: Year Ended December 31, 2021 2020 2019 Total quarterly cash dividends declared, per share $ — $ 0.70 $ 2.80 Total cash dividends paid (in thousands) — 11,361 45,552 The Company suspended payment of cash dividends upon the onset of the pandemic and as part of accepting benefits from the Treasury under the Payroll Support Programs, the Company has agreed not to pay cash dividends through September 30, 2022.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Investments The Company measures certain financial assets and liabilities at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Accounting standards pertaining to fair value measurements establish a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1 - Defined as observable inputs such as quoted prices in active markets for identical assets or liabilities Level 2 - Defined as inputs other than Level 1 inputs that are either directly or indirectly observable Level 3 - Defined as unobservable inputs for which little or no market data exists, therefore requiring an entity to develop its own assumptions The Company uses the market approach valuation technique to determine fair value for investment securities. The assets classified as Level 1 consist of money market funds for which original cost approximates fair value. The assets classified as Level 2 consist of commercial paper, municipal debt securities, federal agency debt securities and corporate debt securities, which are valued using quoted market prices or alternative pricing sources including transactions involving identical or comparable assets and models utilizing market observable inputs. The Company has no investment securities classified as Level 3. For those assets classified as Level 2 that are not in active markets, the Company obtains fair value from pricing sources using quoted market prices for identical or comparable instruments, and uses pricing models which include all significant observable inputs: maturity dates, issue dates, settlement dates, benchmark yields, reported trades, broker-dealer quotes, issue spreads, benchmark securities, bids, offers and other market related data. These inputs are observable or can be derived from, or corroborated by, observable market data for substantially the full term of the asset. Financial instruments measured at fair value on a recurring basis: As of December 31, 2021 As of December 31, 2020 (in thousands) Total Level 1 Level 2 Total Level 1 Level 2 Cash equivalents Money market funds $ 25,019 $ 25,019 $ — $ 5,340 $ 5,340 $ — Commercial paper 179,455 — 179,455 48,908 — 48,908 Municipal debt securities 63,875 — 63,875 34,338 — 34,338 Federal agency debt securities — — — 51,400 — 51,400 Total cash equivalents 268,349 25,019 243,330 139,986 5,340 134,646 Short-term Commercial paper 419,469 — 419,469 229,821 — 229,821 Corporate debt securities 234,436 — 234,436 166,768 — 166,768 Municipal debt securities 165,572 — 165,572 87,290 — 87,290 Federal agency debt securities — — — 48,598 — 48,598 Total short-term 819,477 — 819,477 532,477 — 532,477 Long-term Municipal debt securities 2,231 — 2,231 — — — Total long-term 2,231 — 2,231 — — — Total financial instruments $ 1,090,057 $ 25,019 $ 1,065,038 $ 672,463 $ 5,340 $ 667,123 There were no significant transfers between Level 1 and Level 2 assets for the years ended December 31, 2021 or 2020. Long-term Debt None of the Company's long-term debt is publicly traded. The Company has determined the estimated fair value of all of this debt to be Level 3, as certain inputs used to determine the fair value of these agreements are unobservable and, therefore, could be sensitive to changes in inputs.The Company utilizes the discounted cash flow method to estimate the fair value of Level 3 debt. Carrying value and estimated fair value of long-term debt, including current maturities and without reduction for related costs: As of December 31, 2021 As of December 31, 2020 (in thousands) Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Fair Value Level Non-publicly held debt $ 1,447,462 $ 1,261,170 $ 1,555,637 $ 1,191,008 3 Other Due to the short term nature, carrying amounts of cash, cash equivalents, restricted cash, accounts receivable and accounts payable approximate fair value.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company is subject to income taxation in the United States and various state jurisdictions in which it operates. In accordance with income tax accounting standards, the Company recognizes tax benefits or expenses on the temporary differences between the financial reporting and tax bases of its assets and liabilities. In 2021, 2020 and 2019, the Company recorded net tax (benefit)/provision of $44.8 million, $(177.0) million and $69.1 million, respectively. Cash taxes, net of (refunds), were $(128.5) million, $(95.2) million and $(2.2) million, respectively. Components of Income before Income Taxes from Continuing Operations The components of income before taxes for domestic and foreign operations consisted of the following: Year ended December 31, (in thousands) 2021 2020 2019 Domestic $ 196,620 $ (361,242) $ 299,330 Foreign — 175 1,917 Total $ 196,620 $ (361,067) $ 301,247 Income Tax Provision/(Benefit) The provision (benefit) for income taxes is composed of the following: Year ended December 31, (in thousands) 2021 2020 2019 Current: Federal $ (494) $ (195,572) $ (34) State 552 (211) 505 Foreign (6) 132 530 Total current 52 (195,651) 1,001 Deferred: Federal 40,693 24,126 63,430 State 4,022 (5,449) 4,699 Foreign — — — Total deferred 44,715 18,677 68,129 Total income tax provision (benefit) $ 44,767 $ (176,974) $ 69,130 Reconciliation of Effective Tax Rate The effective tax rate on income before income taxes differed from the federal statutory income tax rate as follows: Year ended December 31, (in thousands) 2021 2020 2019 Income tax expense (benefit) at federal statutory rate $ 41,575 $ (70,459) $ 63,262 State income taxes, net of federal income tax benefit 4,257 (5,495) 5,070 CARES Act — (97,988) — Foreign income tax expense (6) 132 530 Other (1,059) (3,164) 268 Total income tax expense $ 44,767 $ (176,974) $ 69,130 Deferred Taxes The major components of the Company’s net deferred tax assets and liabilities are as follows: As of December 31, (in thousands) 2021 2020 Deferred tax assets: Accrued vacation $ 1,197 $ 1,024 Accrued bonus 4,086 — State taxes 248 — Accrued property taxes 1,048 1,111 Stock-based compensation expense 1,372 1,025 Net operating loss 7,827 15,979 Tax credit 4,523 10,995 Less: valuation allowance 1,214 1,214 Total deferred tax assets 19,087 28,920 Deferred tax liabilities: Prepaid expenses 3,625 2,517 Depreciation 352,123 308,266 Other 9,476 19,900 Total deferred tax liabilities 365,224 330,683 Net deferred tax liabilities $ 346,137 $ 301,763 Net Operating Loss and Tax Credit Carryforwards Pursuant to the CARES Act, the Company carried back net operating tax losses generated in 2018, 2019 and 2020 in the amounts of $185.4 million, $116.7 million and $422.1 million respectively to tax years ended December 31, 2013 through December 31, 2016. The net operating loss carryback resulted in prior years’ foreign tax credits and general business credits generated in 2014 - 2020 in the amount of $5.7 million and $5.2 million respectively to be released. During 2021, the Company utilized $2.3 million and $4.5 million of the released foreign tax credits and general business credits. Unused foreign tax credit and general business credits will expire in 2026 – 2030, but the Company expects to utilize these credits prior to the expiration. In addition, as of December 31, 2021, the Company recognized state net operating loss carryforwards for income tax purposes in the amount of $7.8 million. A portion of the state net operating loss carryforward amounts will expire between 2022 and 2040 while a majority of these net operating losses have an indefinite carryforward period.

Related Party Transactions (Not

Related Party Transactions (Notes)	12 Months Ended
	Dec. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Related Party TransactionsDuring the years ended December 31, 2021, 2020 and 2019, there were no related party transactions that required disclosure.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Company leases assets including aircraft, office facilities, office equipment, certain airport and terminal facilities, and other space. These commitments have remaining non-cancelable lease terms, which range from 2022 to 2048. Refer to Note 8 for more information on the Company's lease agreements. The Company's contractual purchase commitments consist primarily of aircraft and engine acquisitions. The total future commitments are as follows: (in thousands) As of December 31, 2021 2022 224,587 2023 632,072 2024 765,758 2025 305,068 Total purchase commitments $ 1,927,485 Aircraft Commitments As of December 31, 2021, the Company had entered into purchase agreements for 51 aircraft which are expected to deliver between 2022 through 2025. Contingencies The Company is party to collective bargaining agreements with the employee groups listed below. As of December 31, 2021, the percentage of full-time equivalent employees for these pay groups were as follows: As of December 31, 2021 Flight Attendants 24.4 % Pilots 33.5 Maintenance Technicians 12.2 Flight Dispatchers 0.9 Total 71.0 % See Item I - Business, for further discussion on the status of each group which has elected union representation. The Company is subject to certain other legal and administrative actions it considers routine to its business activities. The Company believes the ultimate outcome of any pending legal or administrative matters will not have a material adverse impact on its financial position, liquidity or results of operations.

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts (Notes)	12 Months Ended
	Dec. 31, 2021
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	Valuation and Qualifying Accounts (in thousands) Balance at Beginning of Year Changes Charged to Statement of Income Accounts Write Offs (net of recoveries) Balance at End of Year Allowance for expendable parts and supplies For the Year Ended December 31, 2021 $ 4,323 $ 1,718 $ — $ 6,041 For the Year Ended December 31, 2020 2,748 1,575 — 4,323 For the Year Ended December 31, 2019 (1) 14,410 2,257 (13,919) 2,748 (1) Increase in write offs mostly related to disposal of MD-80 fleet parts in 2019.

Operating Segment Segment Repor

Operating Segment Segment Reporting (Notes)	12 Months Ended
	Dec. 31, 2021
Segment Reporting [Abstract]
Segment Reporting Disclosure [Text Block]	Segments Operating segments are components of a company for which separate financial and operating information is regularly evaluated and reported to the Chief Operating Decision Maker ("CODM"), and is used to allocate resources and analyze performance. The Company's CODM is the executive leadership team, which reviews information about the Company's two operating segments: Airline and Sunseeker Resort. Airline Segment The Airline segment operates as a single business unit and includes all scheduled service air transportation, ancillary air-related products and services, third party products and services, fixed fee contract air transportation and other airline-related revenue. The CODM evaluation includes, but is not limited to, route and flight profitability data, ancillary and third party product and service offering statistics, and fixed fee contract information when making resource allocation decisions with the goal of optimizing consolidated financial results. Sunseeker Resort Segment The Sunseeker Resort segment represents activity related to the development and construction of Sunseeker Resort in Southwest Florida, as well as the operation of Kingsway Golf Course. Plans for the resort include a 500-room hotel and two towers offering an estimated 180 one, two and three-bedroom suites, bar and restaurant options, and other amenities. The golf course is a short drive from the resort site and is considered, from a planning and strategic perspective, to be an additional resort amenity. The construction of Sunseeker Resort is an extension of the Company's leisure travel focus and it is expected that many customers flying to Southwest Florida on Allegiant will elect to stay at this resort and enjoy its amenities. Other non-Airline Segment The other non-airline segment includes the Teesnap golf course management solution and Allegiant Nonstop family entertainment centers. Allegiant Nonstop family entertainment centers featured games, attractions, and food facilities. Due to the impacts of COVID-19, the Company permanently closed the Allegiant Nonstop locations in Warren, MI, Clearfield, Utah, and the Allegiant Nonstop location in West Jordan, Utah, which was being developed. In April 2021, the Company closed on a transaction to sell 85 percent of Teesnap. Selected information for the Company's segments and the reconciliation to the consolidated financial statement amounts are as follows: (in thousands) Airline Sunseeker Resort Other non - airline Consolidated Year Ended December 31, 2021 Operating revenue: Passenger $ 1,578,436 $ — $ — $ 1,578,436 Third party products 86,487 — — 86,487 Fixed fee contract 41,184 — — 41,184 Other 133 (6) 1,676 1,803 Operating income (loss) 271,716 (7,998) (643) 263,075 Interest expense, net 64,529 1,818 — 66,347 Depreciation and amortization 180,923 112 — 181,035 Capital expenditures 309,982 50,629 — 360,611 Year Ended December 31, 2020 Operating revenue: Passenger $ 902,187 $ — $ — $ 902,187 Third party products 46,482 — — 46,482 Fixed fee contract 26,865 — — 26,865 Other 1,462 650 12,427 14,539 Operating income (loss) (104,745) (145,721) (30,519) (280,985) Interest expense, net 50,355 562 — 50,917 Depreciation and amortization 174,882 615 770 176,267 Capital expenditures 262,748 45,160 442 308,350 Year Ended December 31, 2019 Operating revenue: Passenger $ 1,682,955 $ — $ — $ 1,682,955 Third party products 70,012 — — 70,012 Fixed fee contract 65,057 — — 65,057 Other 4,474 2,048 16,419 22,941 Operating income (loss) 388,740 (6,588) (18,202) 363,950 Interest expense, net 58,112 1,694 — 59,806 Depreciation and amortization 151,060 1,250 3,542 155,852 Capital expenditures 438,765 66,659 18,304 523,728 Total assets were as follows as of the dates indicated: (in thousands) As of December 31, 2021 As of December 31, 2020 Airline $ 3,871,751 $ 3,214,523 Sunseeker Resort 119,032 36,612 Other non-airline 290 7,790 Consolidated $ 3,991,073 $ 3,258,925

Subsequent Events (Notes)

Subsequent Events (Notes)	12 Months Ended
	Dec. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsUnder the agreement entered into with The Boeing Company (“Boeing”) to acquire fifty (50) newly manufactured Boeing 737-MAX aircraft, the Company made pre-delivery deposits of $44.5 million in January 2022.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies - (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation [Policy Text Block]	Basis of Presentation The accompanying consolidated financial statements include the accounts of Allegiant Travel Company and its majority-owned operating subsidiaries. The Company's investments in unconsolidated affiliates, which are 50 percent or less owned, are accounted for under the equity or cost method. All intercompany balances and transactions have been eliminated. The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Actual results could differ from these estimates.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents Cash and cash equivalents include investments and interest bearing instruments with original maturities of three months or less. Such investments are carried at cost which approximates fair value.
Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]	Restricted Cash
Receivable [Policy Text Block]	Accounts Receivable Accounts receivable are carried at face amount which approximates fair value. In addition to income tax receivables, the accounts receivable consist primarily of amounts due from credit card companies associated with the sale of tickets for future travel. These receivables are short-term and generally settle within a few days of sale. There are also receivables related to commission amounts due from Enterprise Holdings Inc. based on terms in the rental car provider agreement and amounts due related to fixed fee charter agreements. If deemed necessary, the Company records charges to its allowance for doubtful accounts for amounts not expected to be collected, for which the balance was immaterial for all years presented.
Marketable Securities, Policy [Policy Text Block]	Short-term and Long-term Investments The Company’s investments in marketable securities are classified as available-for-sale and are reported at fair value with the net unrealized gain or (loss) reported as a component of accumulated other comprehensive income (loss) in shareholders’ equity. For investments in an unrealized loss position, the Company determines whether a credit loss exists by considering information about the collectability of the instrument and current market conditions. There have been no credit losses in the years presented. Investment securities with original maturities of three months or less are classified as cash equivalents. Investment securities with original maturities greater than three months are classified as either short-term investments or long-term investments based on the maturity date in relation to the balance sheet date. Short-term investments have a maturity date less than or equal to one year from the balance sheet date, and long-term investments have a maturity date greater than one year from the balance sheet date. The amortized cost of investment securities sold is determined by the specific identification method with any realized gains or losses reflected in other (income) expense. The Company had minimal realized losses during the years ended December 31, 2021, 2020, and 2019. The Company believes unrealized losses related to debt securities are not other-than-temporary and does not intend to sell these securities prior to amortized cost recoverability. The Company attempts to minimize its concentration risk with regard to its cash, cash equivalents, and investment portfolio. This is accomplished by diversifying and limiting amounts among different counterparties, the type of investment, and the amount invested in any individual security, commercial paper, or money market fund.
Inventory, Policy [Policy Text Block]	Expendable Parts, Supplies and Fuel, Net Expendable parts, supplies and fuel inventories are valued at cost using the first-in, first-out method. Such inventories are charged to expense as they are used in operations. An obsolescence allowance for expendable parts and supplies is based on salvage values and the average remaining useful life of the Airbus fleet. The obsolescence allowance for expendable parts and supplies was $6.0 million and $4.3 million at December 31, 2021 and 2020, respectively. Rotable aircraft parts inventories are included in property and equipment.
Lessee, Leases [Policy Text Block]	Operating Lease Right-of-Use Asset and Liability The Company determines if an arrangement is a lease at inception and has lease agreements for aircraft, office facilities, office equipment, certain airport and terminal facilities, and other space and assets with non-cancelable lease terms. Certain real estate and property leases, aircraft leases, and various other operating leases are measured on the balance sheet with a lease liability and right-of-use ("ROU") asset. Airport terminal leases mostly include variable lease payments outside of those based on a fixed index, and are therefore excluded from consideration. ROU assets represent the Company's right to use an underlying asset for the lease term, and lease liabilities represent the obligation to make scheduled lease payments. ROU assets and liabilities are recognized on the lease commencement date based on the present value of lease payments over the lease term. The present value of lease payments is calculated using an estimated incremental borrowing rate at lease commencement, which takes into consideration recent debt issuances as well as other applicable market data available. Lease payments include fixed payments, variable payments based on an index or rate, reasonably certain purchase options, termination penalties, and others as required by the Accounting Standards (ASU) 2016-02, Leases (Topic 842). Lease payments do not include variable lease payments other than those that depend on an index or rate, any guarantee by the lessee of the lessor’s debt, or any amount allocated to non-lease components. Lease terms include options to extend when it is reasonably certain that the option will be exercised. Leases with a term of 12 months or less are not recorded on the balance sheet. Additionally, lease and non-lease components are accounted for as a single lease component for real estate agreements.
Property, Plant and Equipment, Policy [Policy Text Block]	Property and Equipment Property and equipment are recorded at cost and depreciated using the straight-line method over their estimated useful lives less any estimated salvage value. Property under finance leases and related obligations are initially recorded at an amount equal to the present value of future minimum lease payments computed on the basis of the Company’s incremental borrowing rate, and depreciation is recorded on a straight-line basis and is included within depreciation and amortization expense. The estimated useful lives of the principal asset classes are shown below. Aircraft, engines and related rotable parts 10-25 years Buildings and leasehold improvements 10-25 years Equipment 3-10 years Computer hardware and software 3-10 years In estimating the useful lives and residual values of aircraft, the Company primarily relies upon actual experience with the same or similar aircraft types, current and projected future market information, and input from other industry sources. Subsequent revisions to these estimates could be caused by changing market prices of the Company’s aircraft, changes in utilization of the aircraft, and other fleet events. Changes in the estimate for useful lives or residual values of the Company’s property and equipment could result in changes in depreciation expense.
Internal Use Software, Policy [Policy Text Block]	Software Capitalization The Company capitalizes certain internal and external costs related to the acquisition and development of computer software during the application development stage of projects. The Company amortizes these capitalized costs using the straight-line method over the estimated useful life of the software, which typically ranges from three
Measurement of Impairment of Long-Lived Assets, Policy [Policy Text Block]	Measurement of Impairment of Long-Lived Assets The Company records impairment losses on long-lived assets used in operations, consisting principally of property and equipment, when events or changes in circumstances indicate, in management’s judgment, that the assets might be impaired, and the undiscounted future cash flows estimated to be generated by those assets are less than the carrying amount of those assets. In making these determinations, the Company utilizes certain assumptions, including, but not limited to: (i) estimated fair value of the assets; and (ii) estimated future cash flows expected to be generated by these assets, which are based on additional assumptions such as asset utilization, length of service for which the asset will be used in operations, and estimated salvage values. For the year ended December 31, 2019, the Company did not incur any impairment losses. For the year ended December 31, 2020, the Company recorded a $161.6 million impairment as a result of COVID-19. For the year ended December 31, 2021, the Company recorded a $0.5 million impairment loss on a building in Chesterfield, Missouri associated with the Allegiant Nonstop family entertainment line of business.
Revenue [Policy Text Block]	Revenue Recognition Passenger revenue Passenger revenue includes scheduled service revenue, ancillary air-related charges, and travel point redemptions from the co-branded Allegiant World Mastercard® credit card and the Company's non-card loyalty program. Scheduled service revenue consists of ticket revenue generated from nonstop flights in the Company’s route network, recognized either when the transportation is provided or when ticket voucher breakage occurs. Nonrefundable scheduled itineraries expire on the date of the intended flight, unless the date is extended by notification from the customer in advance. Itineraries sold for transportation not yet used, as well as unexpired credits, are included in air traffic liability. Ancillary air-related charges include various services and products related to the flight such as baggage fees, the use of the Company’s website to purchase scheduled service transportation, advance seat assignments, and other services which are not included in the base ticket price. Revenues from air-related charges are recognized when the transportation is provided. If a customer cancels a flight, a voucher may be issued for a future flight, at which time the associated revenue is recognized upon completion of the future flight. Additionally, the Company estimates the value of vouchers that will expire unused and recognizes such revenue at the time of issuance. Various taxes and fees, assessed on the sale of tickets to customers, are collected by the Company serving as an agent, and remitted to taxing authorities. These taxes and fees are not included as revenue in the Company’s consolidated statements of income and are recorded as a liability until remitted to the appropriate taxing authority. Revenue from travel point redemptions from the co-branded credit card and the Loyalty program are described in the Affinity Credit Card Program and Allways Rewards Loyalty Program sections below. Third party products revenue Ancillary third party products revenue is generated from the sale of hotel rooms, rental cars and ticket attractions, as well as marketing revenue associated with the co-branded credit card. Revenue from the sale of third party products is recognized at the time the product is utilized, such as the time a purchased hotel room is occupied. Revenue from the sale of third party products is recorded net of amounts paid to wholesale providers, travel agent commissions, and transaction costs. Pursuant to the co-brand arrangement with Bank of America, the Company has various performance obligations which are collectively referred to as the marketing component. These obligations consist of use of the Company’s brand and access to its member lists, and certain other advertising and marketing elements. The marketing component is recorded as third party products revenue in the period in which points are awarded to the credit card holders. Fixed fee contract revenue Fixed fee contract revenue consists of agreements to provide charter service on a year-round and ad hoc basis. Fixed fee contract revenue is recognized when the transportation is provided. Other revenue Other revenue is generated from non-airline activities as well as leasing aircraft and engines. Lease revenue is recognized ratably over the lease term. Affinity Credit Card Program The Allegiant World Mastercard® is issued by Bank of America through which arrangement points are sold and consideration is received under an agreement that expires in 2029. Under this arrangement, the Company identified the following deliverables: travel points to be awarded (the travel component), use of the Company’s brand and access to its member lists, and certain other advertising and marketing elements (collectively the marketing component). Each of these deliverables is accounted for separately and allocation of the consideration from the agreement is determined based on the relative selling price of each deliverable. The Company applied a level of management judgment and estimation in determining the best estimate of selling price for each deliverable by considering multiple inputs and methods including, but not limited to, the redemption value of points awarded, discounted cash flows, brand value, volume discounts, published selling prices, number of points to be awarded and number of points expected to be redeemed.
Advertising Cost [Policy Text Block]	Advertising Costs
Earnings Per Share, Policy [Policy Text Block]	Earnings per Share Basic and diluted earnings per share are computed pursuant to the two-class method as opposed to the treasury method. Under the two-class method, the Company attributes net income to two classes, common stock and unvested restricted stock awards. Unvested restricted stock awards granted to employees under the Company’s Long-Term Incentive Plan are considered participating securities because they receive non-forfeitable rights to cash dividends at the same rate as common stock. Diluted net income per share is calculated using the more dilutive of two methods. Under both methods, the exercise of employee stock options is assumed using the treasury stock method. The assumption of vesting of restricted stock, however, differs as described below: 1. Assume vesting of restricted stock using the treasury stock method. 2. Assume unvested restricted stock awards are not vested, and allocate earnings to common shares and unvested restricted stock awards using the two-class method. For the years ended December 31, 2021 and 2019, the second method above was used in the computation because it was more dilutive than the first method. Given the loss position in 2020, both methods yield the same result. The following table sets forth the computation of net income (loss) per share on a basic and diluted basis for the periods indicated: Year ended December 31, (in thousands, except per share data) 2021 2020 2019 Basic: Net income (loss) $ 151,853 $ (184,093) $ 232,117 Less income allocated to participating securities (2,218) (236) (3,413) Net income (loss) attributable to common stock $ 149,635 $ (184,329) $ 228,704 Earnings (loss) per share, basic $ 8.69 $ (11.53) $ 14.27 Weighted-average shares outstanding 17,212 15,992 16,027 Diluted: Net income (loss) $ 151,853 $ (184,093) $ 232,117 Less income allocated to participating securities (2,215) (236) (3,410) Net income (loss) attributable to common stock $ 149,638 $ (184,329) $ 228,707 Earnings (loss) per share, diluted $ 8.68 $ (11.53) $ 14.26 Weighted-average shares outstanding 17,212 15,992 16,027 Dilutive effect of stock options and restricted stock 145 — 51 Adjusted weighted-average shares outstanding under treasury stock method 17,357 15,992 16,078 Participating securities excluded under two-class method (126) — (37) Adjusted weighted-average shares outstanding under two-class method 17,231 15,992 16,041 Stock awards outstanding of 815, 24,004, and 19,928 shares (not in thousands) as of December 31, 2021, 2020, and 2019, respectively, were excluded from the computation of diluted earnings per share as they were antidilutive.
Share-based Payment Arrangement [Policy Text Block]	Share-Based Compensation The Company accounts for share-based compensation in accordance with accounting standards which require the compensation cost related to share-based payment transactions be recognized in the Company’s consolidated statements of income. The share-based cost is measured based on grant date fair value. The Company’s share-based employee compensation plan is more fully discussed in Note 13.
Income Tax, Policy [Policy Text Block]	Income Taxes The Company recognizes deferred income taxes based on the asset and liability method required by accounting standards. Deferred tax assets and liabilities are determined based on the timing differences between book basis for financial reporting purposes and tax basis of the asset and liability and measured using the enacted tax rates and provisions of the enacted tax law. A valuation allowance for deferred tax assets is provided if it is more likely than not that some portion or all of the deferred tax assets will not be realized. The Company determines the net non-current deferred tax assets or liabilities separately for federal, state, foreign and other local jurisdictions. The Company’s income tax returns are subject to examination by the Internal Revenue Service (“IRS”) and other tax authorities in the jurisdictions where the Company operates. The Company assesses potentially unfavorable outcomes of such examinations based on the criteria set forth in uncertain tax position accounting standards. The accounting standards prescribe a minimum recognition threshold a tax position is required to meet before being recognized in the financial statements. Accounting standards for income taxes utilize a two-step approach for evaluating tax positions. Recognition (Step I) occurs when the Company concludes that a tax position, based on its technical merits, is more likely than not to be sustained upon examination. Measurement (Step II) is only addressed if the position is deemed to be more likely than not to be sustained. Under Step II, the tax benefit is measured as the largest amount of benefit that is greater than 50 percent likely of being realized upon settlement.
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements On June 16, 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments. The standard requires the use of an “expected loss” model on certain types of financial instruments. The standard also amends the impairment model for available-for-sale debt securities and requires estimated credit losses to be recorded as allowances instead of reductions to amortized cost of the securities. The Company adopted this accounting standard prospectively as of January 1, 2020, and it did not have a significant impact on its consolidated financial statements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. This standard is intended to simplify various aspects related to accounting for income taxes and is effective for fiscal years beginning after December 15, 2020, including interim periods therein, and early adoption is permitted. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application of Topic 740. The Company adopted ASU 2019-12 in the first quarter of 2021 and its adoption did not have a material effect on the Company's consolidated financial statements.
Deposits and Other Assets	Deposits and Other AssetsDeposits and Other Assets consist primarily of airport deposits, aircraft purchase deposits, deposits as required by the construction loan agreement and a note receivable to the counter-party in the Company’s joint venture alliance. The Company also had outstanding receivables from third parties as of December 31, 2021 and 2020, of which $12.4 million and $10.9 million respectively, was due more than one year after the balance sheet date.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Estimated Useful Lives	The estimated useful lives of the principal asset classes are shown below. Aircraft, engines and related rotable parts 10-25 years Buildings and leasehold improvements 10-25 years Equipment 3-10 years Computer hardware and software 3-10 years Property and equipment consisted of the following: As of December 31, (in thousands) 2021 2020 Flight equipment $ 2,576,315 $ 2,331,499 Computer hardware and software 160,459 149,727 Land and buildings/leasehold improvements 86,036 87,030 Other property and equipment 132,875 80,601 Total property and equipment 2,955,685 2,648,857 Less accumulated depreciation and amortization (696,178) (598,546) Property and equipment, net $ 2,259,507 $ 2,050,311
Schedule of Earnings Per Share, Basic and Diluted	The following table sets forth the computation of net income (loss) per share on a basic and diluted basis for the periods indicated: Year ended December 31, (in thousands, except per share data) 2021 2020 2019 Basic: Net income (loss) $ 151,853 $ (184,093) $ 232,117 Less income allocated to participating securities (2,218) (236) (3,413) Net income (loss) attributable to common stock $ 149,635 $ (184,329) $ 228,704 Earnings (loss) per share, basic $ 8.69 $ (11.53) $ 14.27 Weighted-average shares outstanding 17,212 15,992 16,027 Diluted: Net income (loss) $ 151,853 $ (184,093) $ 232,117 Less income allocated to participating securities (2,215) (236) (3,410) Net income (loss) attributable to common stock $ 149,638 $ (184,329) $ 228,707 Earnings (loss) per share, diluted $ 8.68 $ (11.53) $ 14.26 Weighted-average shares outstanding 17,212 15,992 16,027 Dilutive effect of stock options and restricted stock 145 — 51 Adjusted weighted-average shares outstanding under treasury stock method 17,357 15,992 16,078 Participating securities excluded under two-class method (126) — (37) Adjusted weighted-average shares outstanding under two-class method 17,231 15,992 16,041

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	Passenger revenue is the most significant category in our reported operating revenues, as outlined below: Year Ended December 31, (in thousands) 2021 2020 2019 Scheduled service $ 769,371 $ 435,668 $ 897,631 Ancillary air-related charges 788,064 453,545 770,206 Loyalty redemptions 21,001 12,974 15,118 Total passenger revenue $ 1,578,436 $ 902,187 $ 1,682,955
Contract with Customer, Asset and Liability	The following table presents the activity of the co-brand point liability as of the dates indicated: Year Ended December 31, (in thousands) 2021 2020 Balance at January 1 $ 21,841 $ 15,613 Points awarded 39,650 19,202 Points redeemed (21,001) (12,974) Balance at December 31 $ 40,490 $ 21,841

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Schedule Of Property Plant And Equipment	The estimated useful lives of the principal asset classes are shown below. Aircraft, engines and related rotable parts 10-25 years Buildings and leasehold improvements 10-25 years Equipment 3-10 years Computer hardware and software 3-10 years Property and equipment consisted of the following: As of December 31, (in thousands) 2021 2020 Flight equipment $ 2,576,315 $ 2,331,499 Computer hardware and software 160,459 149,727 Land and buildings/leasehold improvements 86,036 87,030 Other property and equipment 132,875 80,601 Total property and equipment 2,955,685 2,648,857 Less accumulated depreciation and amortization (696,178) (598,546) Property and equipment, net $ 2,259,507 $ 2,050,311

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2021
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following: As of December 31, (in thousands) 2021 2020 Salaries, wages and benefits $ 38,313 $ 21,878 Sunseeker Resort development 12,241 14,084 Maintenance and repairs 11,718 12,847 Loyalty program liability 17,787 10,929 Station expenses 21,297 10,526 Property taxes 7,853 9,042 Interest 10,519 6,560 Passenger taxes and fees 14,324 4,686 Advertising accruals 1,863 890 Other accruals 26,977 24,651 Total accrued liabilities $ 162,892 $ 116,093

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Summary of Long-Term Debt	Long-term debt consisted of the following: As of December 31, (in thousands) 2021 2020 Fixed-rate debt and finance lease obligations due through 2032 $ 827,382 $ 525,240 Variable-rate debt due through 2029 915,157 1,133,771 Total long-term debt and finance lease obligations, net of related costs 1,742,539 1,659,011 Less current maturities, net of related costs 130,053 217,234 Long-term debt and finance lease obligations, net of current maturities and related costs $ 1,612,486 $ 1,441,777 Weighted average fixed-interest rate on debt 5.8 % 5.7 % Weighted average variable-interest rate on debt 2.5 % 2.4 %
Schedule of Maturities of Long-term Debt [Table Text Block]	Maturities of long-term debt as of December 31, 2021, for the next five years and thereafter, in the aggregate, are: (in thousands) As of December 31, 2021 2022 $ 130,053 2023 130,723 2024 800,849 2025 107,434 2026 100,776 Thereafter 472,704 Total debt and finance lease obligations, net of related costs $ 1,742,539

Lease (Tables)

Lease (Tables)	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Lease, Cost [Table Text Block]	The components of lease costs recognized on the statements of income were as follows: Year Ended December 31, (in thousands) Classification on the Statements of Income 2021 2020 Finance lease costs: Amortization of assets Depreciation and amortization $ 13,274 $ 6,631 Interest on lease liabilities Interest expense 11,168 5,335 Operating lease cost Aircraft lease rentals; Station operations; Maintenance and repairs; Other operating expense 22,697 12,616 Variable lease cost Station operations; Maintenance and repairs; Other operating expense 2,565 3,560 Total lease cost $ 49,704 $ 28,142
Leases of Lessee Disclosure [Text Block]	The table below presents the lease-related assets and liabilities recorded on the balance sheet. As of December 31, (in thousands) Classification on the Balance Sheet 2021 2020 Assets Operating lease assets Operating lease right-of-use assets, net $ 130,087 $ 115,911 Finance lease assets Property and equipment, net 338,469 133,175 Total lease assets $ 468,556 $ 249,086 Liabilities Current Operating Current operating lease liabilities $ 19,081 $ 14,313 Finance Current maturities of long-term debt and finance lease obligations 16,960 9,767 Noncurrent Operating Noncurrent operating lease liabilities 115,067 102,289 Finance Long-term debt and finance lease obligations 301,532 117,060 Total lease liabilities $ 452,640 $ 243,429 Weighted-average remaining lease term Operating leases 7.7 years 8.3 years Finance leases 7.8 years 7.6 years Weighted-average discount rate Operating leases 5.4 % 5.4 % Finance leases 5.2 % 5.0 %
Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]	The table below presents supplemental cash flow information related to leases during the year ended December 31. Year Ended December 31, (in thousands) 2021 2020 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows for operating leases $ 18,987 $ 13,102 Operating cash flows for finance leases 10,697 5,335 Financing cash flows for finance leases 14,675 15,908
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	The table below indicates the future minimum payments of lease liabilities as of December 31, 2021. (in thousands) Operating Leases Finance Leases 2022 $ 25,781 $ 32,822 2023 25,618 44,813 2024 25,299 29,268 2025 23,158 29,268 2026 13,184 28,968 Thereafter 49,317 250,141 Total lease payments 162,357 415,280 Less imputed interest (28,209) (96,788) Total lease obligations 134,148 318,492 Less current obligations (19,081) (16,960) Long-term lease obligations $ 115,067 $ 301,532

Stockholders' Equity Share Repu

Stockholders' Equity Share Repurchases (Tables)	12 Months Ended
	Dec. 31, 2021
Share Repurchases [Abstract]
Treasury Stock	Share repurchases consisted of the following during the periods indicated: Year Ended December 31, 2021 2020 2019 Shares repurchased (1) — 197,570 103,943 Average price per share $ — $ 155.14 $ 141.64 Total (in thousands) $ — $ 30,651 $ 14,723 (1) Share amounts shown above include only open market repurchases and do not include shares withheld from employees for tax withholding obligations related to restricted stock vestings, which were 19,001 and 27,700 shares for 2020 and 2019, respectively.
Dividends Declared	Cash dividends declared by the Board and paid by the Company consisted of the following during the periods indicated: Year Ended December 31, 2021 2020 2019 Total quarterly cash dividends declared, per share $ — $ 0.70 $ 2.80 Total cash dividends paid (in thousands) — 11,361 45,552

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Assets Measured at Fair Value On a Recurring Basis	Financial instruments measured at fair value on a recurring basis: As of December 31, 2021 As of December 31, 2020 (in thousands) Total Level 1 Level 2 Total Level 1 Level 2 Cash equivalents Money market funds $ 25,019 $ 25,019 $ — $ 5,340 $ 5,340 $ — Commercial paper 179,455 — 179,455 48,908 — 48,908 Municipal debt securities 63,875 — 63,875 34,338 — 34,338 Federal agency debt securities — — — 51,400 — 51,400 Total cash equivalents 268,349 25,019 243,330 139,986 5,340 134,646 Short-term Commercial paper 419,469 — 419,469 229,821 — 229,821 Corporate debt securities 234,436 — 234,436 166,768 — 166,768 Municipal debt securities 165,572 — 165,572 87,290 — 87,290 Federal agency debt securities — — — 48,598 — 48,598 Total short-term 819,477 — 819,477 532,477 — 532,477 Long-term Municipal debt securities 2,231 — 2,231 — — — Total long-term 2,231 — 2,231 — — — Total financial instruments $ 1,090,057 $ 25,019 $ 1,065,038 $ 672,463 $ 5,340 $ 667,123
Debt Instrument, Fair Value Disclosure	Carrying value and estimated fair value of long-term debt, including current maturities and without reduction for related costs: As of December 31, 2021 As of December 31, 2020 (in thousands) Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Fair Value Level Non-publicly held debt $ 1,447,462 $ 1,261,170 $ 1,555,637 $ 1,191,008 3

Income Taxes Income Taxes (Tabl

Income Taxes Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign	The components of income before taxes for domestic and foreign operations consisted of the following: Year ended December 31, (in thousands) 2021 2020 2019 Domestic $ 196,620 $ (361,242) $ 299,330 Foreign — 175 1,917 Total $ 196,620 $ (361,067) $ 301,247
Schedule of Components of Income Tax Expense (Benefit)	The provision (benefit) for income taxes is composed of the following: Year ended December 31, (in thousands) 2021 2020 2019 Current: Federal $ (494) $ (195,572) $ (34) State 552 (211) 505 Foreign (6) 132 530 Total current 52 (195,651) 1,001 Deferred: Federal 40,693 24,126 63,430 State 4,022 (5,449) 4,699 Foreign — — — Total deferred 44,715 18,677 68,129 Total income tax provision (benefit) $ 44,767 $ (176,974) $ 69,130
Schedule of Effective Income Tax Rate Reconciliation	The effective tax rate on income before income taxes differed from the federal statutory income tax rate as follows: Year ended December 31, (in thousands) 2021 2020 2019 Income tax expense (benefit) at federal statutory rate $ 41,575 $ (70,459) $ 63,262 State income taxes, net of federal income tax benefit 4,257 (5,495) 5,070 CARES Act — (97,988) — Foreign income tax expense (6) 132 530 Other (1,059) (3,164) 268 Total income tax expense $ 44,767 $ (176,974) $ 69,130
Schedule of Deferred Tax Assets and Liabilities	The major components of the Company’s net deferred tax assets and liabilities are as follows: As of December 31, (in thousands) 2021 2020 Deferred tax assets: Accrued vacation $ 1,197 $ 1,024 Accrued bonus 4,086 — State taxes 248 — Accrued property taxes 1,048 1,111 Stock-based compensation expense 1,372 1,025 Net operating loss 7,827 15,979 Tax credit 4,523 10,995 Less: valuation allowance 1,214 1,214 Total deferred tax assets 19,087 28,920 Deferred tax liabilities: Prepaid expenses 3,625 2,517 Depreciation 352,123 308,266 Other 9,476 19,900 Total deferred tax liabilities 365,224 330,683 Net deferred tax liabilities $ 346,137 $ 301,763

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2021
Employee Benefit Plans [Abstract]
Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity [Table Text Block]	The following table provides information about the Company’s ESPP activity during 2021, 2020, and 2019: Total number of shares purchased in year Average price paid per share Weighted-average fair value of discount under the ESPP (1) As of December 31, 2019 38,464 $ 133.54 $ 23.51 As of December 31, 2020 56,866 $ 90.63 $ 14.10 As of December 31, 2021 39,760 $ 174.68 $ 30.00
Schedule of Nonvested Restricted Stock Units Activity	A summary of the status of non-vested restricted stock grants during the years ended December 31, 2021, 2020 and 2019 is presented below: Shares Weighted Average Grant Date Fair Value Per Share Non-vested at December 31, 2018 196,194 $ 153.88 Granted 218,477 143.72 Vested (104,816) 152.07 Forfeited (15,047) 148.97 Non-vested at December 31, 2019 294,808 $ 147.25 Granted 267,169 137.80 Vested (291,303) 147.58 Forfeited (5,147) 145.82 Non-vested at December 31, 2020 265,527 $ 142.25 Granted 120,456 194.66 Vested (197,530) 136.71 Forfeited (6,900) 147.05 Non-vested at December 31, 2021 181,553 $ 183.63

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Contractual Obligation, Fiscal Year Maturity Schedule	The Company's contractual purchase commitments consist primarily of aircraft and engine acquisitions. The total future commitments are as follows: (in thousands) As of December 31, 2021 2022 224,587 2023 632,072 2024 765,758 2025 305,068 Total purchase commitments $ 1,927,485
Employees Under Collective Bargaining Agreements [Table Text Block]	The Company is party to collective bargaining agreements with the employee groups listed below. As of December 31, 2021, the percentage of full-time equivalent employees for these pay groups were as follows: As of December 31, 2021 Flight Attendants 24.4 % Pilots 33.5 Maintenance Technicians 12.2 Flight Dispatchers 0.9 Total 71.0 %

Valuation and Qualifying Acco_2

Valuation and Qualifying Accounts (Tables)	12 Months Ended
	Dec. 31, 2021
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Schedule Of Valuation And Qualifying Accounts	(in thousands) Balance at Beginning of Year Changes Charged to Statement of Income Accounts Write Offs (net of recoveries) Balance at End of Year Allowance for expendable parts and supplies For the Year Ended December 31, 2021 $ 4,323 $ 1,718 $ — $ 6,041 For the Year Ended December 31, 2020 2,748 1,575 — 4,323 For the Year Ended December 31, 2019 (1) 14,410 2,257 (13,919) 2,748 (1) Increase in write offs mostly related to disposal of MD-80 fleet parts in 2019.

Operating Segment (Tables)

Operating Segment (Tables)	12 Months Ended
	Dec. 31, 2021
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Selected information for the Company's segments and the reconciliation to the consolidated financial statement amounts are as follows: (in thousands) Airline Sunseeker Resort Other non - airline Consolidated Year Ended December 31, 2021 Operating revenue: Passenger $ 1,578,436 $ — $ — $ 1,578,436 Third party products 86,487 — — 86,487 Fixed fee contract 41,184 — — 41,184 Other 133 (6) 1,676 1,803 Operating income (loss) 271,716 (7,998) (643) 263,075 Interest expense, net 64,529 1,818 — 66,347 Depreciation and amortization 180,923 112 — 181,035 Capital expenditures 309,982 50,629 — 360,611 Year Ended December 31, 2020 Operating revenue: Passenger $ 902,187 $ — $ — $ 902,187 Third party products 46,482 — — 46,482 Fixed fee contract 26,865 — — 26,865 Other 1,462 650 12,427 14,539 Operating income (loss) (104,745) (145,721) (30,519) (280,985) Interest expense, net 50,355 562 — 50,917 Depreciation and amortization 174,882 615 770 176,267 Capital expenditures 262,748 45,160 442 308,350 Year Ended December 31, 2019 Operating revenue: Passenger $ 1,682,955 $ — $ — $ 1,682,955 Third party products 70,012 — — 70,012 Fixed fee contract 65,057 — — 65,057 Other 4,474 2,048 16,419 22,941 Operating income (loss) 388,740 (6,588) (18,202) 363,950 Interest expense, net 58,112 1,694 — 59,806 Depreciation and amortization 151,060 1,250 3,542 155,852 Capital expenditures 438,765 66,659 18,304 523,728 Total assets were as follows as of the dates indicated: (in thousands) As of December 31, 2021 As of December 31, 2020 Airline $ 3,871,751 $ 3,214,523 Sunseeker Resort 119,032 36,612 Other non-airline 290 7,790 Consolidated $ 3,991,073 $ 3,258,925

Organization and Business of _2

Organization and Business of Company - Narrative (Details)	12 Months Ended
	Dec. 31, 2021segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments	1

Unusual or Infrequently Occur_2

Unusual or Infrequently Occurring Items (Details) $ in Thousands	Mar. 31, 2021Aircraft	Sep. 30, 2020USD ($)	Dec. 31, 2021USD ($)Aircraft	Dec. 31, 2020USD ($)Aircraft	Sep. 30, 2021USD ($)	Apr. 30, 2021USD ($)	Apr. 23, 2021USD ($)shares	Jan. 15, 2021USD ($)	Oct. 31, 2020USD ($)	Apr. 30, 2020USD ($)	Feb. 13, 2020USD ($)	Feb. 01, 2019USD ($)
Unusual or Infrequent Item, or Both [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | shares							924
Debt Instrument, Term	24 months
Operating Special Charge, Total			$ 13,998	$ 306,299
Non-Operating Special Charge, Total			0	26,632
Special Charges, Total			13,998	332,931
Asset impairment charges				161,600
Other Aircraft Related Costs			$ 2,500	$ 98,000
Number of Aircraft Retired | Aircraft			2	8
Number of Engines Retired | Aircraft			3	5
Number of Aircraft In Sale-Leaseback Transactions | Aircraft	3		8	8
Postemployment Benefits, Period Expense				$ 35,100
Construction Suspension Expense				5,000
Other Expenses			$ 500	6,600
Total Proceeds from Payroll Support Program Grant						$ 98,400		$ 91,800
Additional Proceeds Received from Payroll Support Program							$ 13,800
Debt Instrument, Face Amount					$ 84,000		$ 1,700		$ 150,000	$ 31,000	$ 545,500	$ 450,000
Share-based Payment Arrangement, Accelerated Cost			10,900
Unsecured Debt | Payroll Support Program Loan CARES Act [Member]
Unusual or Infrequent Item, or Both [Line Items]
Proceeds From Payroll Support Program, Low-Interest Loan		$ 24,700
Payroll Support Program2
Unusual or Infrequent Item, or Both [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | shares							179.23
Allegiant Air
Unusual or Infrequent Item, or Both [Line Items]
Operating Special Charge			13,453	141,713
Non-Operating Special Charge			0	0
Special Charges, Total			13,453	141,713
Sunseeker Resorts
Unusual or Infrequent Item, or Both [Line Items]
Operating Special Charge			0	137,994
Non-Operating Special Charge			0	26,632
Special Charges, Total			0	164,626
Other
Unusual or Infrequent Item, or Both [Line Items]
Operating Special Charge			545	26,592
Non-Operating Special Charge			0	0
Special Charges, Total			$ 545	26,592
Asset impairment charges				$ 26,600

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Accounts Receivable, before Allowance for Credit Loss, Noncurrent	$ 12.4	$ 10.9
Inventory Valuation Reserves	6	4.3
Interest Costs Capitalized Adjustment	0.2	4.1	$ 4.5
Capitalized Computer Software, Net	43.3	42.3
Capitalized Computer Software, Amortization	$ 10.6	9.6	12.2
Building | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	10.00
Building | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	25.00
Equipment And Leasehold Improvements | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	3.00
Equipment And Leasehold Improvements | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	10.00
Computer Hardware and Software | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	3.00
Property, Plant and Equipment, Useful Life	3 years
Computer Hardware and Software | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	10.00
Property, Plant and Equipment, Useful Life	10 years
A320 Series Engine
Property, Plant and Equipment [Line Items]
Deferred Costs for Heavy Maintenance	$ 23.3	12.8
Amortization of Other Deferred Charges	21	17.6
Airbus A320 Aircraft Series
Property, Plant and Equipment [Line Items]
Deferred Costs for Heavy Maintenance	39	22.6
Amortization of Other Deferred Charges	$ 21.1	$ 19.9	$ 14.9
Airbus A320 Aircraft Series | Aircraft And Engines | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	10.00
Airbus A320 Aircraft Series | Aircraft And Engines | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	25.00

Summary of Significant Accoun_5

Summary of Significant Accounting Policies Basis (Details)	Dec. 31, 2021
Accounting Policies [Abstract]
Equity Method Investment, Ownership Percentage	50.00%

Summary of Significant Accoun_6

Summary of Significant Accounting Policies Accounts Receivable (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Receivables [Abstract]
Accounts Receivable, before Allowance for Credit Loss, Noncurrent	$ 12.4	$ 10.9

Summary of Significant Accoun_7

Summary of Significant Accounting Policies Expendable Parts, Supplies and Fuel (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Expendable Parts, Supplies and Fuel [Abstract]
Inventory Valuation Reserves	$ 6	$ 4.3

Summary of Significant Accoun_8

Summary of Significant Accounting Policies Interest Costs Capitalized (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest Cost [Abstract]
Interest Costs Capitalized Adjustment	$ 0.2	$ 4.1	$ 4.5

Summary of Significant Accoun_9

Summary of Significant Accounting Policies Software Capitalization (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Capitalized Computer Software [Abstract]
Capitalized Computer Software, Net	$ 43.3	$ 42.3
Capitalized Computer Software, Amortization	$ 10.6	$ 9.6	$ 12.2

Summary of Significant Accou_10

Summary of Significant Accounting Policies Aircraft Maintenance and Repair Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
A320 Series Engine
Servicing Asset at Amortized Cost [Line Items]
Deferred Costs for Heavy Maintenance	$ 23.3	$ 12.8
Amortization of Other Deferred Charges	21	17.6
Airbus A320 Aircraft Series
Servicing Asset at Amortized Cost [Line Items]
Deferred Costs for Heavy Maintenance	39	22.6
Amortization of Other Deferred Charges	$ 21.1	$ 19.9	$ 14.9

Summary of Significant Accou_11

Summary of Significant Accounting Policies Measurement of Impairment of Long-Lived Assets (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment charges	$ 161.6

Summary of Significant Accou_12

Summary of Significant Accounting Policies Allways Rewards Loyalty Program (Details) - Allways Rewards Loyalty Program	1 Months Ended
	Aug. 31, 2021point
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number Of Points Earned For Every Dollar Spent	1
Number Of Points Earned For Every Dollar Spent Over Five Hundred Dollars	2

Summary of Significant Accou_13

Summary of Significant Accounting Policies Advertising Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Advertising Expense	$ 31,300	$ 12,400	$ 29,100

Summary of Significant Accou_14

Summary of Significant Accounting Policies Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	815	24,004	19,928
Net income (loss)	$ 151,853	$ (184,093)	$ 232,117
Less income allocated to participating securities	(2,218)	(236)	(3,413)
Net income (loss) attributable to common stock	$ 149,635	$ (184,329)	$ 228,704
Basic (in dollars per share)	$ 8.69	$ (11.53)	$ 14.27
Basic (in shares)	17,212,000	15,992,000	16,027,000
Less income allocated to participating securities	$ (2,215)	$ (236)	$ (3,410)
Net income (loss) attributable to common stock	$ 149,638	$ (184,329)	$ 228,707
Diluted (in dollars per share)	$ 8.68	$ (11.53)	$ 14.26
Diluted (in shares)		15,992,000	16,041,000
Dilutive effect of stock options and restricted stock (in shares)	145,000	0	51,000
Adjusted weighted-average shares outstanding under treasury stock method (in shares)	17,357,000	15,992,000	16,078,000
Participating securities excluded under two-class method (in shares)	(126,000)	0	(37,000)
Adjusted weighted-average shares outstanding under two-class method (in shares)	17,231,000	15,992,000	16,041,000

Summary of Significant Accou_15

Summary of Significant Accounting Policies Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets, net	$ 130,087	$ 115,911
Operating Lease, Liability	$ 134,148

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Passenger	$ 1,578,436	$ 902,187	$ 1,682,955
Air Traffic Liability, Current		307,500
Air Traffic Liability, Recognized	88.00%
Contract with Customer, Liability, Credit Voucher Bookings	$ 67,000
Contract with Customer, Liability, Forward Bookings	$ 240,500
Revenue from Contract with Customer, Duration	12 months
Scheduled Service Revenue
Disaggregation of Revenue [Line Items]
Passenger	$ 769,371	435,668	897,631
Air-related revenue
Disaggregation of Revenue [Line Items]
Passenger	788,064	453,545	770,206
Co-brand Revenue
Disaggregation of Revenue [Line Items]
Passenger	$ 21,001	$ 12,974	$ 15,118

Revenue Recognition Points Liab

Revenue Recognition Points Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Contract with Customer, Liability	$ 40,490	$ 21,841	$ 15,613
Points awarded	39,650	19,202
Points redeemed	(21,001)	(12,974)
Points Liability	17,800	10,900
Disaggregation of Revenue [Line Items]
Points Liability	$ 17,800	$ 10,900

Property and Equipment (Details

Property and Equipment (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)Aircraft	Dec. 31, 2020USD ($)
Property, Plant and Equipment [Abstract]
Flight Equipment, Gross	$ 2,576,315	$ 2,331,499
Computer Hardware and Software	160,459	149,727
Land and buildings/leasehold improvements	86,036	87,030
Property, Plant and Equipment, Other, Gross	132,875	80,601
Property, Plant and Equipment, Gross, Total	2,955,685	2,648,857
Less accumulated depreciation and amortization	(696,178)	(598,546)
Property, Plant and Equipment, Net	2,259,507	2,050,311
Capital Expenditures Incurred but Not yet Paid	$ 17,700	$ 16,900
Capital Addition Purchase Commitments | Airbus A320 Aircraft Series
Property, Plant and Equipment [Line Items]
Number of Aircraft Committed To Purchase | Aircraft	51

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accrued Liabilities, Current [Abstract]
Salaries, wages and benefits	$ 38,313	$ 21,878
Sunseeker Resort development	12,241	14,084
Maintenance and repairs	11,718	12,847
Loyalty program liability	17,787	10,929
Station expenses	21,297	10,526
Property taxes	7,853	9,042
Interest	10,519	6,560
Passenger taxes and fees	14,324	4,686
Advertising accruals	1,863	890
Other accruals	26,977	24,651
Total accrued liabilities	$ 162,892	$ 116,093

Long-Term Debt (Detail)

Long-Term Debt (Detail) $ in Thousands	Mar. 31, 2021USD ($)	Feb. 13, 2020USD ($)	Oct. 31, 2021USD ($)	Feb. 28, 2019USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2021USD ($)Aircraft	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Apr. 20, 2030	Sep. 30, 2021USD ($)	Apr. 23, 2021USD ($)	Oct. 31, 2020USD ($)	Apr. 30, 2020USD ($)Aircraft	Mar. 31, 2020USD ($)	Oct. 31, 2019USD ($)Aircraft	Sep. 30, 2019	Mar. 31, 2019Aircraft	Feb. 01, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)Aircraft
Debt Instrument, Face Amount		$ 545,500								$ 84,000	$ 1,700	$ 150,000	$ 31,000					$ 450,000
Debt Instrument, Increase (Decrease), Net		$ 100,000
Total long-term debt and finance lease obligations, net of related costs						$ 1,742,539	$ 1,659,011
Long-term Debt, Current Maturities						130,053	217,234
Long-term Debt, Excluding Current Maturities						$ 1,612,486	1,441,777
Number Of Aircrafts Included As Collateral | Aircraft						0							2
Line of Credit Facility, Maximum Borrowing Capacity	$ 50,000																		$ 81,000
Debt Instrument, Term	24 months
Debt Instrument, Periodic Payment, Principal				$ 1,400
Gain (Loss) on Extinguishment of Debt						$ (71)	(1,222)	$ (3,677)
Capital Leased Assets, Number of Units | Aircraft						15
Liabilities						$ 2,767,521	2,559,562
PP&E from VIEs						3,991,073	3,258,925
Debt Issuance Costs, Net						23,400	23,500
Sunseeker Resorts
PP&E from VIEs						119,032	36,612
Variable Interest Entity, Primary Beneficiary [Member]
PP&E from VIEs						84,406	187,166
Fixed Rate
Notes Payable						$ 827,382	$ 525,240
Long-term Debt, Weighted Average Interest Rate, at Point in Time						5.80%	5.70%
Variable Rate
Notes Payable						$ 915,157	$ 1,133,771
Long-term Debt, Weighted Average Interest Rate, at Point in Time						2.50%	2.40%
Payroll Support Program Loan CARES Act [Member] | Forecast [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Debt Instrument, Basis Spread on Variable Rate									2.00%
Senior Secured Notes due 2024 [Member]
Debt Instrument, Interest Rate, Stated Percentage						8.50%
Unsecured Debt | Payroll Support Program Loan CARES Act [Member]
Debt Instrument, Interest Rate, Stated Percentage						1.00%
Proceeds From Payroll Support Program, Low-Interest Loan					$ 24,700
Long-term Debt
reduction in debt interest rate		15000.00%
Delayed-Draw Construction Loan | Sunseeker Resorts
Debt Instrument, Interest Rate, Stated Percentage			5.75%
Debt Instrument, Face Amount			$ 350,000
Debt Instrument, Periodic Payment, Principal			$ 26,000
Long-term Debt						$ 175,000
Consolidated Variable Interest Entity
Debt, Weighted Average Interest Rate														3.80%	3.20%	4.00%
PP&E from VIEs																				$ 37,800
Consolidated Variable Interest Entity | Variable Interest Entity, Primary Beneficiary [Member]
Liabilities														$ 44,000	$ 23,500					$ 44,000
PP&E from VIEs														$ 38,500	$ 18,600
Consolidated Variable Interest Entity | Airbus A320 Aircraft Series
Number Of Aircrafts Included As Collateral | Aircraft															1		1			1
Variable Interest Entity, Primary Beneficiary [Member] | Consolidated Variable Interest Entity
Liabilities																				$ 44,000

Long-Term Debt - Components of

Long-Term Debt - Components of Long-Term Debt (Detail) $ in Thousands	Mar. 31, 2021USD ($)	Dec. 31, 2021USD ($)Aircraft	Sep. 30, 2021USD ($)	Apr. 23, 2021USD ($)	Dec. 31, 2020USD ($)	Oct. 31, 2020USD ($)	Apr. 30, 2020USD ($)Aircraft	Feb. 13, 2020USD ($)	Feb. 01, 2019USD ($)	Dec. 31, 2018USD ($)
Components of Long-Term Debt [Abstract]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months		$ 130,053
Long-term Debt, Maturities, Repayments of Principal in Year Two		130,723
Long-term Debt, Maturities, Repayments of Principal in Year Three		800,849
Long-term Debt, Maturities, Repayments of Principal in Year Four		107,434
Long-term Debt, Maturities, Repayments of Principal in Year Five		100,776
Long-term Debt, Maturities, Repayments of Principal after Year Five		472,704
Secured Long-term Debt, Noncurrent		1,742,539			$ 1,659,011
Debt Issuance Costs, Net		$ 23,400			$ 23,500
Debt Instrument, Face Amount			$ 84,000	$ 1,700		$ 150,000	$ 31,000	$ 545,500	$ 450,000
Line of Credit Facility, Maximum Borrowing Capacity	$ 50,000									$ 81,000
Repayments of Lines of Credit	$ 46,500
Debt Instrument, Term	24 months
Number Of Aircrafts Included As Collateral | Aircraft		0					2
Deposit into Construction Disbursement Account		$ 30,000

Lease (Details)

Lease (Details) $ in Thousands	Mar. 31, 2021Aircraft	Dec. 31, 2021USD ($)Aircraft	Dec. 31, 2020USD ($)Aircraft	Dec. 31, 2019USD ($)
Leases [Abstract]
Capital Leased Assets, Number of Units | Aircraft		15
Operating Leased Assets, Number Of Units | Aircraft		17
operating right of use asset, net		$ 130,087	$ 115,911
Finance Lease, Right-of-Use Asset		338,469	133,175
Total Right-of-Use Asset		468,556	249,086
Accrued liabilities		19,081	14,313
Finance Lease, Liability, Current		16,960	9,767
Noncurrent operating lease liabilities		115,067	102,289
Finance Lease, Liability, Noncurrent		301,532	117,060
Total Lease Liability		$ 452,640	$ 243,429
Operating Lease, Weighted Average Discount Rate, Percent		5.40%	5.40%
Finance Lease, Weighted Average Discount Rate, Percent		5.20%	5.00%
Operating Lease, Weighted Average Remaining Lease Term		7 years 8 months 12 days	8 years 3 months 18 days
Finance Lease, Weighted Average Remaining Lease Term		7 years 9 months 18 days	7 years 7 months 6 days
Number of Aircraft In Sale-Leaseback Transactions | Aircraft	3	8	8
Proceeds from sale-leaseback transactions		$ 0	$ 87,580	$ 0
Sale and Leaseback Transaction, Gain (Loss), Net		53,200
Sale Leaseback Transaction, Net Proceeds, Financing Activities		$ 105,000

Lease Lease Costs (Details)

Lease Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Finance Lease, Right-of-Use Asset, Amortization	$ 13,274	$ 6,631
Finance Lease, Interest Expense	11,168	5,335
Finance Lease, Interest Payment on Liability	10,697	5,335
Operating Lease, Cost	22,697	12,616
Variable Lease, Cost	2,565	3,560
Lease, Cost	$ 49,704	$ 28,142

Lease Cash paid for lease (Deta

Lease Cash paid for lease (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash paid for lease [Abstract]
Operating Lease, Payments	$ 18,987	$ 13,102
Finance Lease, Interest Payment on Liability	10,697	5,335
Finance Lease, Principal Payments	$ 14,675	$ 15,908

Lease Scheduled Lease Payments

Lease Scheduled Lease Payments Commitments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Scheduled Lease Payments Commitments [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Year Two	$ 25,618
Lessee, Operating Lease, Liability, Payments, Due Year Three	25,299
Lessee, Operating Lease, Liability, Payments, Due Year Four	23,158
Lessee, Operating Lease, Liability, Payments, Due Year Five	13,184
Lessee, Operating Lease, Liability, Payments, Due after Year Five	49,317
Lessee, Operating Lease, Liability, Payments, Due	162,357
Operating Lease, Liability	134,148
Accrued liabilities	(19,081)	$ (14,313)
Noncurrent operating lease liabilities	115,067	102,289
Finance Lease, Liability, to be Paid, Year One	32,822
Finance Lease, Liability, Payments, Due Year Two	44,813
Finance Lease, Liability, Payments, Due Year Three	29,268
Finance Lease, Liability, Payments, Due Year Four	29,268
Finance Lease, Liability, Payments, Due Year Five	28,968
Finance Lease, Liability, Payments, Due after Year Five	250,141
Finance Lease, Liability, Payment, Due	415,280
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(28,209)
Finance Lease, Liability, Undiscounted Excess Amount	(96,788)
Finance Lease, Liability	318,492
Finance Lease, Liability, Current	(16,960)	(9,767)
Finance Lease, Liability, Noncurrent	301,532	$ 117,060
Lessee, Operating Lease, Liability, to be Paid, Year One	$ 25,781

Stockholders' Equity (Detail)

Stockholders' Equity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock Repurchased During Period, Shares	0	197,570	103,943
Treasury Stock Acquired, Average Cost Per Share (in Dollars per share)	$ 0	$ 155.14	$ 141.64
Stock Repurchased During Period, Value	$ 0	$ 30,651	$ 14,723
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		19,001	27,700
Dividends Payable, Amount Per Share	$ 0	$ 0.70	$ 2.80
Dividends	$ 0	$ 11,361	$ 45,552

Fair Value Measurements (Detail

Fair Value Measurements (Detail) - Fair Value Measurements at Reporting Date Using - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Investment Securities	$ 1,090,057	$ 672,463
Short-term investments
Investment Securities	819,477	532,477
Long-term investments
Investment Securities	2,231	0
Fair Value, Inputs, Level 1
Investment Securities	25,019	5,340
Fair Value, Inputs, Level 1 | Short-term investments
Investment Securities	0	0
Fair Value, Inputs, Level 1 | Long-term investments
Investment Securities	0	0
Fair Value, Inputs, Level 2
Investment Securities	1,065,038	667,123
Fair Value, Inputs, Level 2 | Short-term investments
Investment Securities	819,477	532,477
Fair Value, Inputs, Level 2 | Long-term investments
Investment Securities	2,231	0
Commercial paper | Short-term investments
Investment Securities	419,469	229,821
Commercial paper | Fair Value, Inputs, Level 1 | Short-term investments
Investment Securities	0	0
Commercial paper | Fair Value, Inputs, Level 2 | Short-term investments
Investment Securities	419,469	229,821
US Government Corporations and Agencies Securities | Short-term investments
Investment Securities	0	48,598
US Government Corporations and Agencies Securities | Fair Value, Inputs, Level 1 | Short-term investments
Investment Securities	0	0
US Government Corporations and Agencies Securities | Fair Value, Inputs, Level 2 | Short-term investments
Investment Securities	0	48,598
Municipal debt securities | Short-term investments
Investment Securities	165,572	87,290
Municipal debt securities | Long-term investments
Investment Securities	2,231	0
Municipal debt securities | Fair Value, Inputs, Level 1 | Short-term investments
Investment Securities	0	0
Municipal debt securities | Fair Value, Inputs, Level 1 | Long-term investments
Investment Securities	0	0
Municipal debt securities | Fair Value, Inputs, Level 2 | Short-term investments
Investment Securities	165,572	87,290
Municipal debt securities | Fair Value, Inputs, Level 2 | Long-term investments
Investment Securities	2,231	0
Corporate debt securities | Short-term investments
Investment Securities	234,436	166,768
Corporate debt securities | Fair Value, Inputs, Level 1 | Short-term investments
Investment Securities	0	0
Corporate debt securities | Fair Value, Inputs, Level 2 | Short-term investments
Investment Securities	234,436	166,768
Cash Equivalents
Cash Equivalents	268,349	139,986
Cash Equivalents | Fair Value, Inputs, Level 1
Cash Equivalents	25,019	5,340
Cash Equivalents | Fair Value, Inputs, Level 2
Cash Equivalents	243,330	134,646
Cash Equivalents | Money market funds
Cash Equivalents	25,019	5,340
Cash Equivalents | Money market funds | Fair Value, Inputs, Level 1
Cash Equivalents	25,019	5,340
Cash Equivalents | Money market funds | Fair Value, Inputs, Level 2
Cash Equivalents	0	0
Cash Equivalents | Commercial paper
Cash Equivalents	179,455	48,908
Cash Equivalents | Commercial paper | Fair Value, Inputs, Level 1
Cash Equivalents	0	0
Cash Equivalents | Commercial paper | Fair Value, Inputs, Level 2
Cash Equivalents	179,455	48,908
Cash Equivalents | US Government Corporations and Agencies Securities
Cash Equivalents	0	51,400
Cash Equivalents | US Government Corporations and Agencies Securities | Fair Value, Inputs, Level 1
Cash Equivalents	0	0
Cash Equivalents | US Government Corporations and Agencies Securities | Fair Value, Inputs, Level 2
Cash Equivalents	0	51,400
Cash Equivalents | Municipal debt securities
Cash Equivalents	63,875	34,338
Cash Equivalents | Municipal debt securities | Fair Value, Inputs, Level 1
Cash Equivalents	0	0
Cash Equivalents | Municipal debt securities | Fair Value, Inputs, Level 2
Cash Equivalents	$ 63,875	$ 34,338

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurements Estimated Fair Value of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Secured Long-term Debt, Noncurrent	$ 1,742,539	$ 1,659,011
Non-Publicly Held Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Secured Long-term Debt, Noncurrent	1,447,462	1,555,637
Fair Value, Inputs, Level 3 | Non-Publicly Held Debt | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	$ 1,261,170	$ 1,191,008

Income Taxes Income Taxes (Deta

Income Taxes Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax Expense (Benefit)	$ 44,767	$ (176,974)	$ 69,130
Income tax refunds	(128,540)	(95,229)	(2,157)
Net Operating Loss, Carryback	422,100	116,700	$ 185,400
Deferred Tax Assets, Operating Loss Carryforwards		5,200		$ 5,700
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	7,800
Deferred Tax Liabilities, Prepaid Expenses	3,625	2,517
Deferred Tax Liabilities, Property, Plant and Equipment	352,123	308,266
Deferred Tax Liabilities, Other	9,476	19,900
Deferred Tax Liabilities, Gross	365,224	330,683
Deferred Income Tax Liabilities, Net	346,137	301,763
Deferred Income Taxes and Tax Credits	4,523	10,995
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	1,214	1,214
Deferred Tax Assets, Net of Valuation Allowance	19,087	$ 28,920
Foreign Tax Credit Carryforward
Income Tax Contingency [Line Items]
Tax Credit Carryforward, Amount	2,300
General Business Tax Credit Carryforward
Income Tax Contingency [Line Items]
Tax Credit Carryforward, Amount	$ 4,500

Income Taxes Components of inco

Income Taxes Components of income/(loss) before income tax expense/(benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income (Loss) from Continuing Operations before Income Taxes, Domestic	$ 196,620	$ (361,242)	$ 299,330
Income (Loss) from Continuing Operations before Income Taxes, Foreign	0	175	1,917
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	$ 196,620	$ (361,067)	$ 301,247

Income Taxes The Components of

Income Taxes The Components of the Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
The Components of the Provision (Benefit) for Income Taxes [Abstract]
Current Federal Tax Expense (Benefit)	$ (494)	$ (195,572)	$ (34)
Current State and Local Tax Expense (Benefit)	552	(211)	505
Current Foreign Tax Expense (Benefit)	(6)	132	530
Current Income Tax Expense (Benefit)	52	(195,651)	1,001
Deferred Federal Income Tax Expense (Benefit)	40,693	24,126	63,430
Deferred State and Local Income Tax Expense (Benefit)	4,022	(5,449)	4,699
Deferred Foreign Income Tax Expense (Benefit)	0	0	0
DeferredTotalIncomeTaxExpenseBenefit	44,715	18,677	68,129
INCOME TAX PROVISION (BENEFIT)	$ 44,767	$ (176,974)	$ 69,130

Income Taxes Reconciliation of

Income Taxes Reconciliation of the Statutory Income Tax Rate and the Company's Effective Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of the Statutory Income Tax Rate and the Company's Effective Tax Rate [Abstract]
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	$ 41,575	$ (70,459)	$ 63,262
Income Tax Reconciliation, State and Local Income Taxes	4,257	(5,495)	5,070
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	0	(97,988)	0
Income Tax Examination, Liability (Refund) Adjustment from Settlement with Taxing Authority	(6)	132	530
Income Tax Reconciliation, Other Reconciling Items	(1,059)	(3,164)	268
INCOME TAX PROVISION (BENEFIT)	$ 44,767	$ (176,974)	$ 69,130

Income Taxes The Major Componen

Income Taxes The Major Components of the Company's Net Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Valuation Allowance
Deferred Income Taxes and Tax Credits	$ 4,523	$ 10,995
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	1,214	1,214
Deferred Tax Assets, Net of Valuation Allowance	19,087	28,920
Deferred Tax Liabilities, Prepaid Expenses	3,625	2,517
Deferred Tax Liabilities, Other	9,476	19,900
Deferred Tax Liabilities, Gross	365,224	330,683
Deferred Income Tax Liabilities, Net	346,137	301,763
Accrued Vacation
Valuation Allowance
Deferred Tax Assets, Gross	1,197	1,024
Deferred Tax Assets, Accrued Bonus
Valuation Allowance
Deferred Tax Assets, Gross	4,086	0
State Taxes
Valuation Allowance
Deferred Tax Assets, Gross	248	0
Accrued Property Taxes
Valuation Allowance
Deferred Tax Assets, Gross	1,048	1,111
Stock Based Compensation
Valuation Allowance
Deferred Tax Assets, Gross	1,372	1,025
Valuation Allowance, Operating Loss Carryforwards
Valuation Allowance
Deferred Tax Assets, Gross	$ 7,827	$ 15,979

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2015	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Contribution Plan, Maximum Annual Contribution Per Employee, Percent	90.00%			25.00%
Defined Contribution Plan, Cost	$ 21,400,000	$ 18,600,000	$ 19,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized						2,000,000
Shares Held in Employee Stock Option Plan, Allocated				1,000,000
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount				$ 25,000
Share-based compensation expense	16,127,000	$ 19,287,000	$ 18,226,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	23,300,000
Cash-settled SARs	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	181,553	265,527	294,808		196,194
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	120,456	267,169	218,477
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(197,530)	(291,303)	(104,816)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(6,900)	(5,147)	(15,047)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 183.63	$ 142.25	$ 147.25		$ 153.88
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	194.66	137.80	143.72
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	136.71	147.58	152.07
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 147.05	$ 145.82	$ 148.97
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value	$ 27,000,000	$ 43,000,000	$ 15,900,000
Restricted Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	2 years 2 months 19 days
Restricted Stock, Stock Options, Cash-Settled SARs And Employee Stock Purchase Program
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Share-based compensation expense	$ 17,200,000	$ 20,100,000	$ 19,200,000
Minimum | Share-based Payment Arrangement, Option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award	5 years
Employee
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	5.00%
Pilot
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Contribution Plan, Maximum Annual Contribution Per Employee, Percent			200.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay			5.00%

Employee Benefit Plans Employee

Employee Benefit Plans Employee Stock Purchase Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2015
Postemployment Benefits [Abstract]
Stock Issued During Period, Shares, Employee Stock Purchase Plans	39,760	56,866	38,464
Weighted Average Fair Value Of Stock Purchase Right Under Employee Stock Purchase Plan	$ 174.68	$ 90.63	$ 133.54
Aggregate Cost Of Discount Off Market Value For Shares Available Under Employee Stock Purchase Plan	$ 30	$ 14.10	$ 23.51
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount				$ 25,000
Defined Contribution Plan, Maximum Annual Contribution Per Employee, Percent	90.00%			25.00%

Commitments and Contingencies_2

Commitments and Contingencies (Detail) $ in Thousands	Dec. 31, 2021USD ($)Aircraft
Long-term Purchase Commitment [Line Items]
2022	$ 224,587
2023	632,072
2024	765,758
2025	305,068
Total purchase commitments	$ 1,927,485
Airbus A320 Aircraft Series
Long-term Purchase Commitment [Line Items]
Number of Aircraft Committed To Purchase | Aircraft	51
Boeing 737 MAX Aircraft Series
Long-term Purchase Commitment [Line Items]
Number of Aircraft Committed To Purchase | Aircraft	50

Commitments and Contingencies C

Commitments and Contingencies Concentration Risk (Details) - Unionized Employees Concentration Risk	12 Months Ended
	Dec. 31, 2021
Flight Attendants
Concentration Risk [Line Items]
Concentration Risk, Percentage	24.40%
Pilots
Concentration Risk [Line Items]
Concentration Risk, Percentage	33.50%
Flight Dispatchers
Concentration Risk [Line Items]
Concentration Risk, Percentage	0.90%
Maintenance Technicians
Concentration Risk [Line Items]
Concentration Risk, Percentage	12.20%
Total Percentage of Employees
Concentration Risk [Line Items]
Concentration Risk, Percentage	71.00%

Valuation and Qualifying Acco_3

Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 4,323	$ 2,748	$ 14,410
Changes Charged to Statement of Income Accounts	1,718		1,575	$ 2,257
Write Offs (net of recoveries)	0	0	(13,919)
Balance at End of Year	$ 6,041	$ 4,323	$ 2,748	$ 14,410

Operating Segment (Details)

Operating Segment (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Apr. 30, 2021	Dec. 31, 2021USD ($)hotel_towersegmentAircraftsuite	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment		2
PP&E from VIEs		$ 3,991,073	$ 3,258,925
Passenger		1,578,436	902,187	$ 1,682,955
Third party products		86,487	46,482	70,012
Fixed fee contracts		41,184	26,865	65,057
Other		1,803	14,539	22,941
Operating Income (Loss)		263,075	(280,985)	363,950
Interest Income (Expense), Net		66,347	50,917	59,806
Depreciation and amortization		181,035	176,267	155,852
Payments to Acquire Productive Assets		$ 360,611	308,350	523,728
Anticipated Number of One, Two, and Three-Bedroom Suites | suite		180
Teesnap
Segment Reporting Information [Line Items]
Investment Sold, Percent	85.00%
Allegiant Air
Segment Reporting Information [Line Items]
PP&E from VIEs		$ 3,871,751	3,214,523
Passenger		1,578,436	902,187	1,682,955
Third party products		86,487	46,482	70,012
Fixed fee contracts		41,184	26,865	65,057
Other		133	1,462	4,474
Operating Income (Loss)		271,716	(104,745)	388,740
Interest Income (Expense), Net		64,529	50,355	58,112
Depreciation and amortization		180,923	174,882	151,060
Payments to Acquire Productive Assets		309,982	262,748	438,765
Sunseeker Resorts
Segment Reporting Information [Line Items]
PP&E from VIEs		119,032	36,612
Other		(6)	650	2,048
Operating Income (Loss)		(7,998)	(145,721)	(6,588)
Interest Income (Expense), Net		1,818	562	1,694
Depreciation and amortization		112	615	1,250
Payments to Acquire Productive Assets		$ 50,629	45,160	66,659
Anticipated Number of Hotel Rooms | Aircraft		500
Anticipated Number of Hotel Towers | hotel_tower		2
Other
Segment Reporting Information [Line Items]
PP&E from VIEs		$ 290	7,790
Other		1,676	12,427	16,419
Operating Income (Loss)		(643)	(30,519)	(18,202)
Interest Income (Expense), Net		0	0	0
Depreciation and amortization		0	770	3,542
Payments to Acquire Productive Assets		$ 0	$ 442	$ 18,304

Subsequent Events (Details)

Subsequent Events (Details) $ in Millions	1 Months Ended
	Jan. 31, 2022USD ($)	Dec. 31, 2021Aircraft
Boeing 737 MAX Aircraft Series
Subsequent Event [Line Items]
Number of Aircraft Committed To Purchase | Aircraft		50
Subsequent Event | Boeing
Subsequent Event [Line Items]
Purchase Commitment, Pre-Delivery Deposit, Amount | $	$ 44.5