Allegiant Travel (ALGT) 10-Q 30 Oct 17 2017 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 16, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Allegiant Travel CO
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		16,077,909
Amendment Flag	false
Entity Central Index Key	1,362,468
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Well Known Seasoned Issuer	Yes
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3

Consolidated Balance Sheets (Cu

Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Common Stock, Par or Stated Value Per Share	$ 0.001
CURRENT ASSETS:
Cash and cash equivalents	$ 74,023	$ 64,711
Restricted cash	17,335	11,647
Short-term investments	351,519	269,269
Accounts receivable	22,780	40,667
Expendable parts, supplies and fuel, net	20,444	16,797
Prepaid expenses	25,102	16,277
Other current assets	6,771	2,686
TOTAL CURRENT ASSETS	517,974	422,054
Property and equipment, net	1,331,798	1,095,314
Long-term investments	76,913	124,834
Deferred major maintenance, net	27,551	17,347
Deposits and other assets	11,736	12,027
TOTAL ASSETS	1,965,972	1,671,576
CURRENT LIABILITIES:
Accounts payable	19,247	16,010
Accrued liabilities	84,210	96,661
Air traffic liability	224,554	194,001
Current maturities of notes payable, net of related costs	165,837	86,226
TOTAL CURRENT LIABILITIES	493,848	392,898
Long-term debt, net of current maturities and related costs	845,727	722,048
Deferred income taxes	140,050	75,338
Other noncurrent liabilities	12,521	7,670
TOTAL LIABILITIES:	1,492,146	1,197,954
SHAREHOLDERS' EQUITY:
Common stock, par value $.001	23	22
Treasury stock	(606,918)	(517,803)
Additional paid in capital	251,032	238,236
Accumulated other comprehensive loss, net	(1,645)	(230)
Retained earnings	831,334	753,397
TOTAL EQUITY	473,826	473,622
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 1,965,972	$ 1,671,576

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Cash dividends declared per share:	$ 0.70	$ 0.70	$ 2.10	$ 1.70
OPERATING REVENUE:
Scheduled service revenue	$ 183,064	$ 177,361	$ 615,777	$ 568,089
Ancillary revenue:
Air-related charges	130,818	127,301	407,789	376,944
Third party products	12,348	11,259	39,394	34,482
Total ancillary revenue	143,166	138,560	447,183	411,426
Fixed fee contract revenue	11,831	9,183	34,120	22,690
Other revenue	10,708	8,377	28,140	24,743
Total operating revenue	348,769	333,481	1,125,220	1,026,948
OPERATING EXPENSES:
Aircraft fuel	80,421	69,305	250,470	182,969
Salary and benefits	88,788	73,424	277,307	211,185
Station operations	37,148	32,252	107,979	96,313
Maintenance and repairs	28,870	26,263	87,611	82,016
Depreciation and amortization	31,894	25,881	92,571	75,962
Sales and marketing	13,884	5,650	36,744	16,774
Aircraft lease rentals	533	472	3,098	924
Other	24,315	23,394	68,440	58,363
Total operating expenses	305,853	256,641	924,220	724,506
OPERATING INCOME	42,916	76,840	201,000	302,442
OTHER (INCOME) EXPENSE:
Interest expense	10,041	6,938	27,332	21,567
Interest income	(1,454)	(781)	(4,193)	(2,102)
Other, net	400	308	1,254	972
Total other expense	8,187	5,849	21,885	18,493
INCOME BEFORE INCOME TAXES	34,729	70,991	179,115	283,949
PROVISION FOR INCOME TAXES	12,436	25,538	66,715	105,669
NET INCOME	$ 22,293	$ 45,453	$ 112,400	$ 178,280
Earnings per share to common stockholders:
Basic	$ 1.39	$ 2.76	$ 6.85	$ 10.74
Diluted	$ 1.39	$ 2.75	$ 6.85	$ 10.73
Shares used for computation:
Basic	15,852,000	16,389,000	16,142,000	16,493,000
Diluted	15,862,000	16,406,000	16,160,000	16,514,000

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income	$ 22,293	$ 45,453	$ 112,400	$ 178,280
Other comprehensive (loss) income:
Change in available for sale securities, net of tax	230	(101)	453	336
Foreign currency translation adjustments	(117)	238	(416)	176
Change in derivatives, net of tax	(193)	(208)	(749)	(533)
Reclassification of derivative gains into Other revenue	(175)	(247)	(703)	(756)
Total other comprehensive loss	(255)	(318)	(1,415)	(777)
TOTAL COMPREHENSIVE INCOME	$ 22,038	$ 45,135	$ 110,985	$ 177,503

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
OPERATING ACTIVITIES:
Net income	$ 112,400	$ 178,280
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	92,571	75,962
Loss on aircraft and other equipment disposals	6,619	3,510
Provision for obsolescence of expendable parts, supplies and fuel	2,900	1,803
Amortization of deferred financing costs	1,059	1,154
Share-based compensation expense	10,847	4,342
Deferred income taxes	64,296	2,336
Changes in certain assets and liabilities:
(Increase) decrease in accounts receivable	17,709	(9,957)
(Increase) decrease in prepaid expenses	(8,825)	3,147
Increase (decrease) in accounts payable	3,671	4,220
Increase (decrease) in accrued liabilities	(11,183)	23,083
Increase (decrease) in air traffic liability	30,553	22,391
Increase Decrease for Deferred Major Maintenance, Net	(14,779)	(4,365)
Other, net	(11,444)	2,187
Net cash provided by operating activities	296,394	308,093
INVESTING ACTIVITIES:
Purchase of investment securities	(273,796)	(291,954)
Proceeds from maturities of investment securities	239,920	268,037
Purchase of property and equipment, including capitalized interest	(333,746)	(264,085)
Other investing activities	1,338	3,999
Net cash used in investing activities	(366,284)	(284,003)
FINANCING ACTIVITIES:
Cash dividends paid to shareholders	(34,462)	(55,895)
Proceeds from the issuance of debt	292,540	120,410
Repurchase of common stock	(90,445)	(63,363)
Principal payments on debt	(88,026)	(63,478)
Other financing activities	(405)	(158)
Net cash provided by (used in) financing activities	79,202	(62,484)
Net change in cash and cash equivalents	9,312	(38,394)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	64,711	87,112
CASH AND CASH EQUIVALENTS AT END OF PERIOD	74,023	48,718
CASH PAYMENTS FOR:
Interest paid, net of amount capitalized	31,733	17,070
Income taxes paid, net of refunds	$ (18,757)	$ 79,818

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited consolidated financial statements include the accounts of Allegiant Travel Company (the “Company”) and its majority-owned operating subsidiaries. The Company has no independent assets or operations, and all guarantees of the Company's publicly held debt are full and unconditional and joint and several. Any subsidiaries of the parent company other than the subsidiary guarantors are minor. All intercompany balances and transactions have been eliminated. These unaudited consolidated financial statements reflect all normal recurring adjustments which management believes are necessary to present fairly the financial position, results of operations, and cash flows of the Company for the respective periods presented. Certain reclassifications have been made to prior year financial statements to conform to classifications used in the current year. Certain information and footnote disclosures normally included in the annual consolidated financial statements prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP") have been omitted pursuant to the rules and regulations of the Securities and Exchange Commission for Form 10-Q. These unaudited interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements of the Company and notes thereto included in the annual report of the Company on Form 10-K for the year ended December 31, 2016, filed with the Securities and Exchange Commission. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities, at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from these estimates. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU 2014-09, "Revenue from Contracts with Customers (Topic 606)" intended to create a unified model to determine when and how revenue is recognized. Under this ASU and subsequently issued amendments, the core principle is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The Company will adopt this standard using the full-retrospective approach on January 1, 2018. Under the new standard, revenue for certain air-related ancillary fees that are directly related to ticket revenue, such as seat fees and baggage fees, will no longer be considered distinct performance obligations separate from passenger travel and will be reclassified into scheduled service revenue. Although finalization is in process, for 2016, the amount expected to be reclassified from air-related charges into scheduled service revenue will be approximately $500 million . In addition, certain fees previously recognized when incurred by the customer, will be deferred and recognized as revenue when air travel is provided and reclassified into scheduled service revenue. The Company believes that adoption will not have a material effect on earnings, although the classification of certain operating revenue and operating expense items will change. In February 2016, the FASB issued ASU 2016-02 related to leases. This standard will require leases with durations greater than twelve months to be recognized on the balance sheet as a lease liability and a corresponding right-of-use asset, and is effective for interim and annual reporting periods beginning after December 15, 2018 with early adoption permitted. The Company has not completed the assessment of this new standard. The Company believes adoption will have a significant impact on its consolidated balance sheets but is not expected to significantly change the recognition, measurement or presentation of associated expense within the consolidated statements of income or cash flows. In August 2016, the FASB issued ASU 2016-15, which amends the guidance in Accounting Standards Codification ("ASC") 230 on the classification of certain cash receipts and payments in the statement of cash flows. The primary purpose of the ASU is to reduce the diversity in practice that has resulted from the lack of consistency on this topic. The standard is effective for annual and interim periods beginning after December 15, 2017, and the Company will adopt it effective January 1, 2018. Significant classification modifications are not expected as a result of adoption.

Property and Equipment

Property and Equipment	9 Months Ended
	Sep. 30, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure	Property and Equipment Property and equipment (in thousands): As of September 30, 2017 As of December 31, 2016 Flight equipment, including pre-delivery deposits $ 1,634,835 $ 1,377,829 Computer hardware and software 119,658 101,850 Other property and equipment 101,121 81,786 Total property and equipment 1,855,614 1,561,465 Less accumulated depreciation and amortization (523,816 ) (466,151 ) Property and equipment, net $ 1,331,798 $ 1,095,314

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt Long-term debt (in thousands): As of September 30, 2017 As of December 31, 2016 Fixed-rate notes payable due through 2020 $ 465,527 $ 465,748 Variable-rate notes payable due through 2027 546,037 342,526 Total long-term debt, net of related costs 1,011,564 808,274 Less current maturities, net of related costs 165,837 86,226 Long-term debt, net of current maturities and related costs $ 845,727 $ 722,048 Weighted average fixed-interest rate 5.41 % 5.41 % Weighted average variable-interest rate 3.25 % 3.16 % Maturities of long-term debt for the remainder of 2017 and for the next five years and thereafter, in the aggregate, are: remaining in 2017 - $25.0 million ; 2018 - $218.3 million ; 2019 - $540.0 million ; 2020 - $73.4 million ; 2021 - $46.1 million ; and $108.9 million thereafter. Secured Debt In the first nine months of 2017, the Company borrowed $236.5 million under loan agreements secured by 12 Airbus A320 series aircraft. The notes bear interest at a floating rate based on LIBOR plus a weighted average margin of 1.62 percent and are payable in monthly or quarterly installments over five or ten years. Senior Secured Revolving Credit Facility In the third quarter of 2017, the Company drew down $56.0 million under its senior secured revolving credit facility, with six Airbus A320 series aircraft in the collateral pool. In 2015, the Company, through a wholly owned subsidiary, entered into this facility under which it is able to borrow up to $56.0 million. The facility had an original term of 24 months, was extended for an additional one-year term in 2016, and may be extended for an additional one-year period, at the lender’s option. Any notes under the facility bear interest at a floating rate based on LIBOR plus 1.85 percent . An individual aircraft may remain in the collateral pool for up to two years.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value, Measurement Inputs, Disclosure	Fair Value Measurements 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 by selling 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. These tiers include: 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; and 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, US Treasury Bonds, 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. The fair value of the Company's derivative instrument is determined using standard valuation models. The significant inputs used in these models are readily available in public markets or can be derived from observable market transactions and therefore have been classified as Level 2. Inputs used in these standard valuation models for derivative instruments include the applicable exchange and interest rates. Financial instruments measured at fair value on a recurring basis (in thousands): As of September 30, 2017 As of December 31, 2016 Total Level 1 Level 2 Total Level 1 Level 2 Cash equivalents Money market funds $ 21,112 $ 21,112 $ — $ 123 $ 123 $ — US Treasury Bonds 4,550 — 4,550 — — — Commercial paper 3,594 — 3,594 — — — Federal agency debt securities — — — 19,399 — 19,399 Municipal debt securities — — — 1,843 — 1,843 Total cash equivalents 29,256 21,112 8,144 21,365 123 21,242 Short-term Municipal debt securities 152,369 — 152,369 78,826 — 78,826 Corporate debt securities 84,667 — 84,667 76,570 — 76,570 Commercial paper 83,051 — 83,051 108,372 — 108,372 Federal agency debt securities 28,432 — 28,432 3,895 — 3,895 US Treasury Bonds 3,000 — 3,000 1,606 — 1,606 Total short-term 351,519 — 351,519 269,269 — 269,269 Long-term Corporate debt securities 71,142 — 71,142 25,048 — 25,048 Federal agency debt securities 5,771 — 5,771 24,160 — 24,160 Derivative instruments 475 — 475 1,660 — 1,660 Municipal debt securities — — — 72,623 — 72,623 US Treasury Bonds — — — 3,003 — 3,003 Total long-term 77,388 — 77,388 126,494 — 126,494 Total financial instruments $ 458,163 $ 21,112 $ 437,051 $ 417,128 $ 123 $ 417,005 The fair value of the Company’s publicly held long-term debt is determined based on inputs that are readily available in public markets or can be derived from information available in publicly quoted markets; therefore, the Company has categorized its publicly held debt as Level 2. The remaining debt agreements are not publicly held. The Company has determined the estimated fair value of these notes 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 (in thousands): As of September 30, 2017 As of December 31, 2016 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Hierarchy Level Publicly held debt $ 451,536 $ 467,340 $ 452,179 $ 468,005 2 Non-publicly held debt 565,512 526,955 360,999 340,866 3 Total long-term debt $ 1,017,048 $ 994,295 $ 813,178 $ 808,871 Due to the short-term nature, carrying amounts of cash, cash equivalents, restricted cash, accounts receivable and accounts payable approximate fair value.

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2017
Derivative Instrument Detail [Abstract]
Derivative Instruments and Hedging Activities Disclosure	Derivative Instruments The Company entered into a foreign currency swap (expiring in 2018) in order to mitigate the foreign currency exchange rate risk associated with the forecasted lease revenue from 12 Airbus A320 series aircraft leased to a European carrier until 2018. The Company uses a cash flow hedge to minimize the variability in cash flows of assets, liabilities and forecasted transactions caused by fluctuations in foreign currency exchange rates. For the nine months ended September 30, 2017 , the net change in fair value recorded in accumulated other comprehensive income related to an unrealized loss on the hedge was $0.7 million compared to $0.5 million for the nine months ended September 30, 2016 . At inception, the Company formally designated and documented this financial instrument as a hedge of a specific underlying exposure, the risk management objective, and the strategy for undertaking the hedge transaction. The Company also assessed whether the financial instrument used in the hedging transactions was effective at offsetting changes in either the fair values or cash flows of the related underlying exposures. This assessment is monitored on at least a quarterly basis, and the change in fair market value of any ineffective portion of a financial instrument would be immediately recognized into earnings. For the nine months ended September 30, 2017 , the Company realized $0.7 million in gains from its cash flow hedge into Other revenue, compared to $0.8 million for the nine months ended September 30, 2016 . As of September 30, 2017 , the Company expects $0.3 million to be reclassified from Other comprehensive income into Other revenue within the next 12 months. At September 30, 2017 , the fair value of the Company's derivative instrument was $0.5 million compared to $1.7 million at December 31, 2016, and is reported in the Company's consolidated balance sheet within deposits and other assets. Refer to Note 4 - Fair Value Measurements for additional information related to the estimated fair value.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Stockholders' Equity	Shareholders’ Equity The Company is authorized by the Board of Directors to acquire its stock through open market purchases under its share repurchase program. As repurchase authority is used, the Board of Directors has, to date, authorized additional expenditures for share repurchases. For the three months ended September 30, 2017 and 2016, the Company had no open market share repurchases. For the nine months ended September 30, 2017 and 2016, share repurchases consisted of the following: Nine Months Ended September 30, 2017 2016 Shares repurchased (not in thousands) 604,497 369,997 Average price per share $ 142.66 $ 166.70 Total (in thousands) $ 86,240 $ 61,679 During the nine months ended September 30, 2017 , the Company declared and paid recurring cash dividends of $2.10 per share, or $34.5 million .

Earnings per Share

Earnings per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share Basic and diluted earnings per share are computed pursuant to the two-class method. Under this method, the Company attributes net income to two classes: common stock and unvested restricted stock. Unvested restricted stock awards granted to employees under the Company’s Long-Term Incentive Plan are considered participating securities as 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 the 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: 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 three and nine months ended September 30, 2017 , the second method, which assumes unvested awards are not vested, was used in the computation because it was more dilutive than the first method. The following table sets forth the computation of net income per share, on a basic and diluted basis, for the periods indicated (share count and dollar amounts other than per-share amounts in table are in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Basic: Net income $ 22,293 $ 45,453 $ 112,400 $ 178,280 Less net income allocated to participating securities (315 ) (298 ) (1,747 ) (1,074 ) Net income attributable to common stock $ 21,978 $ 45,155 $ 110,653 $ 177,206 Net income per share, basic $ 1.39 $ 2.76 $ 6.85 $ 10.74 Weighted-average shares outstanding 15,852 16,389 16,142 16,493 Diluted: Net income $ 22,293 $ 45,453 $ 112,400 $ 178,280 Less net income allocated to participating securities (315 ) (297 ) (1,745 ) (1,073 ) Net income attributable to common stock $ 21,978 $ 45,156 $ 110,655 $ 177,207 Net income per share, diluted $ 1.39 $ 2.75 $ 6.85 $ 10.73 Weighted-average shares outstanding 15,852 16,389 16,142 16,493 Dilutive effect of stock options and restricted stock 18 26 60 34 Adjusted weighted-average shares outstanding under treasury stock method 15,870 16,415 16,202 16,527 Participating securities excluded under two-class method (8 ) (9 ) (42 ) (13 ) Adjusted weighted-average shares outstanding under two-class method 15,862 16,406 16,160 16,514 For the three and nine months ended September 30, 2017 , anti-dilutive shares excluded from the calculation of earnings per share were 129,989 and 51,439 (shares not in thousands), respectively.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies As of September 30, 2017 , the Company had firm commitments to purchase the following aircraft: Aircraft Type Number of Aircraft Under Contract Airbus A319 3 Airbus A320 17 In addition, the Company has entered into lease agreements for an additional 13 Airbus A320 aircraft expected to be delivered between fourth quarter 2017 and the end of 2018. Future minimum fixed payments for the Company's commitments related to the acquisition of aircraft (including aircraft lease obligations), airport fees under use and lease agreements, and other operating lease obligations are as follows as of September 30, 2017 (in thousands): As of September 30, 2017 Remaining in 2017 $ 141,093 2018 140,702 2019 113,873 2020 76,016 2021 34,723 Thereafter 231,358 Total commitments $ 737,765 Contingencies The Company is subject to certain 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.

Related Party

Related Party	9 Months Ended
	Sep. 30, 2017
Related Party Transactions [Abstract]
Related Party Transactions Disclosure	Related Party Transactions The Company previously entered into a lease agreement for approximately 70,000 square feet of office space in a building in which the Company’s Chairman and Chief Executive Officer ("CEO") and the Company's President owned minority interests as limited partners. The Company exercised its option to terminate the lease effective in May 2015 and paid $1.3 million in January 2016 in settlement of related litigation. Entities owned or controlled by the Company's Chairman and CEO have been paid for the building of corporate training content. This approach to training focuses on concept mastery, recognizing that individuals learn at varying paces, through different styles, and is designed to ensure the trainee fully understands each module before moving on to more advanced training. During the nine months ended September 30, 2017 and 2016, the Company made payments to these entities of $0.2 million and $1.4 million , respectively, and no further payments are expected.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2017
Subsequent Event [Line Items]
Subsequent Events [Text Block]	Subsequent Events In October 2017, the Company received funding under loan agreements secured by two Airbus A320 aircraft for $68.0 million , executed in September 2017. The notes bear interest at a floating rate based on LIBOR plus a margin of 1.45 percent and are payable in quarterly installments through 2027. Also in October 2017, the Company executed purchase agreements for four Airbus A320 series aircraft for which delivery is expected in the fourth quarter 2017. The Company's board of directors approved a fleet plan at the October 2017 meeting which further accelerates the retirement of the MD-80 fleet to fourth quarter 2018. As a result of this operational update, the Company is evaluating the MD-80 fleet and its related assets for impairment. The carrying value of these assets was $40.2 million at September 30, 2017.

Summary of Significant Accoun16

Summary of Significant Accounting Policies - (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements include the accounts of Allegiant Travel Company (the “Company”) and its majority-owned operating subsidiaries. The Company has no independent assets or operations, and all guarantees of the Company's publicly held debt are full and unconditional and joint and several. Any subsidiaries of the parent company other than the subsidiary guarantors are minor. All intercompany balances and transactions have been eliminated. These unaudited consolidated financial statements reflect all normal recurring adjustments which management believes are necessary to present fairly the financial position, results of operations, and cash flows of the Company for the respective periods presented. Certain reclassifications have been made to prior year financial statements to conform to classifications used in the current year. Certain information and footnote disclosures normally included in the annual consolidated financial statements prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP") have been omitted pursuant to the rules and regulations of the Securities and Exchange Commission for Form 10-Q. These unaudited interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements of the Company and notes thereto included in the annual report of the Company on Form 10-K for the year ended December 31, 2016, filed with the Securities and Exchange Commission. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities, at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from these estimates.
New Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU 2014-09, "Revenue from Contracts with Customers (Topic 606)" intended to create a unified model to determine when and how revenue is recognized. Under this ASU and subsequently issued amendments, the core principle is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The Company will adopt this standard using the full-retrospective approach on January 1, 2018. Under the new standard, revenue for certain air-related ancillary fees that are directly related to ticket revenue, such as seat fees and baggage fees, will no longer be considered distinct performance obligations separate from passenger travel and will be reclassified into scheduled service revenue. Although finalization is in process, for 2016, the amount expected to be reclassified from air-related charges into scheduled service revenue will be approximately $500 million . In addition, certain fees previously recognized when incurred by the customer, will be deferred and recognized as revenue when air travel is provided and reclassified into scheduled service revenue. The Company believes that adoption will not have a material effect on earnings, although the classification of certain operating revenue and operating expense items will change. In February 2016, the FASB issued ASU 2016-02 related to leases. This standard will require leases with durations greater than twelve months to be recognized on the balance sheet as a lease liability and a corresponding right-of-use asset, and is effective for interim and annual reporting periods beginning after December 15, 2018 with early adoption permitted. The Company has not completed the assessment of this new standard. The Company believes adoption will have a significant impact on its consolidated balance sheets but is not expected to significantly change the recognition, measurement or presentation of associated expense within the consolidated statements of income or cash flows. In August 2016, the FASB issued ASU 2016-15, which amends the guidance in Accounting Standards Codification ("ASC") 230 on the classification of certain cash receipts and payments in the statement of cash flows. The primary purpose of the ASU is to reduce the diversity in practice that has resulted from the lack of consistency on this topic. The standard is effective for annual and interim periods beginning after December 15, 2017, and the Company will adopt it effective January 1, 2018. Significant classification modifications are not expected as a result of adoption.

Property and Equipment (Tables)

Property and Equipment (Tables)	9 Months Ended
	Sep. 30, 2017
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	Property and equipment (in thousands): As of September 30, 2017 As of December 31, 2016 Flight equipment, including pre-delivery deposits $ 1,634,835 $ 1,377,829 Computer hardware and software 119,658 101,850 Other property and equipment 101,121 81,786 Total property and equipment 1,855,614 1,561,465 Less accumulated depreciation and amortization (523,816 ) (466,151 ) Property and equipment, net $ 1,331,798 $ 1,095,314

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Summary of Long-Term Debt	Long-term debt (in thousands): As of September 30, 2017 As of December 31, 2016 Fixed-rate notes payable due through 2020 $ 465,527 $ 465,748 Variable-rate notes payable due through 2027 546,037 342,526 Total long-term debt, net of related costs 1,011,564 808,274 Less current maturities, net of related costs 165,837 86,226 Long-term debt, net of current maturities and related costs $ 845,727 $ 722,048 Weighted average fixed-interest rate 5.41 % 5.41 % Weighted average variable-interest rate 3.25 % 3.16 %

Long-Term Debt Schedule of Matu

Long-Term Debt Schedule of Maturities of Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2017
Schedule of Maturities of Long-Term Debt [Abstract]
Schedule of Maturities of Long-term Debt	Maturities of long-term debt for the remainder of 2017 and for the next five years and thereafter, in the aggregate, are: remaining in 2017 - $25.0 million ; 2018 - $218.3 million ; 2019 - $540.0 million ; 2020 - $73.4 million ; 2021 - $46.1 million ; and $108.9 million thereafter.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Assets Measured at Fair Value On a Recurring Basis	Financial instruments measured at fair value on a recurring basis (in thousands): As of September 30, 2017 As of December 31, 2016 Total Level 1 Level 2 Total Level 1 Level 2 Cash equivalents Money market funds $ 21,112 $ 21,112 $ — $ 123 $ 123 $ — US Treasury Bonds 4,550 — 4,550 — — — Commercial paper 3,594 — 3,594 — — — Federal agency debt securities — — — 19,399 — 19,399 Municipal debt securities — — — 1,843 — 1,843 Total cash equivalents 29,256 21,112 8,144 21,365 123 21,242 Short-term Municipal debt securities 152,369 — 152,369 78,826 — 78,826 Corporate debt securities 84,667 — 84,667 76,570 — 76,570 Commercial paper 83,051 — 83,051 108,372 — 108,372 Federal agency debt securities 28,432 — 28,432 3,895 — 3,895 US Treasury Bonds 3,000 — 3,000 1,606 — 1,606 Total short-term 351,519 — 351,519 269,269 — 269,269 Long-term Corporate debt securities 71,142 — 71,142 25,048 — 25,048 Federal agency debt securities 5,771 — 5,771 24,160 — 24,160 Derivative instruments 475 — 475 1,660 — 1,660 Municipal debt securities — — — 72,623 — 72,623 US Treasury Bonds — — — 3,003 — 3,003 Total long-term 77,388 — 77,388 126,494 — 126,494 Total financial instruments $ 458,163 $ 21,112 $ 437,051 $ 417,128 $ 123 $ 417,005
Fair Value, Liabilities Measured on Recurring Basis	Carrying value and estimated fair value of long-term debt, including current maturities and without reduction for related costs (in thousands): As of September 30, 2017 As of December 31, 2016 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Hierarchy Level Publicly held debt $ 451,536 $ 467,340 $ 452,179 $ 468,005 2 Non-publicly held debt 565,512 526,955 360,999 340,866 3 Total long-term debt $ 1,017,048 $ 994,295 $ 813,178 $ 808,871

Stockholders' Equity Repurchase

Stockholders' Equity Repurchases (Tables)	9 Months Ended
	Sep. 30, 2017
Equity, Class of Treasury Stock [Line Items]
Treasury Stock [Text Block]	For the three months ended September 30, 2017 and 2016, the Company had no open market share repurchases. For the nine months ended September 30, 2017 and 2016, share repurchases consisted of the following: Nine Months Ended September 30, 2017 2016 Shares repurchased (not in thousands) 604,497 369,997 Average price per share $ 142.66 $ 166.70 Total (in thousands) $ 86,240 $ 61,679

Earnings per Share (Tables)

Earnings per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Computation of Net Income Per Share, Basic and Diluted	The following table sets forth the computation of net income per share, on a basic and diluted basis, for the periods indicated (share count and dollar amounts other than per-share amounts in table are in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Basic: Net income $ 22,293 $ 45,453 $ 112,400 $ 178,280 Less net income allocated to participating securities (315 ) (298 ) (1,747 ) (1,074 ) Net income attributable to common stock $ 21,978 $ 45,155 $ 110,653 $ 177,206 Net income per share, basic $ 1.39 $ 2.76 $ 6.85 $ 10.74 Weighted-average shares outstanding 15,852 16,389 16,142 16,493 Diluted: Net income $ 22,293 $ 45,453 $ 112,400 $ 178,280 Less net income allocated to participating securities (315 ) (297 ) (1,745 ) (1,073 ) Net income attributable to common stock $ 21,978 $ 45,156 $ 110,655 $ 177,207 Net income per share, diluted $ 1.39 $ 2.75 $ 6.85 $ 10.73 Weighted-average shares outstanding 15,852 16,389 16,142 16,493 Dilutive effect of stock options and restricted stock 18 26 60 34 Adjusted weighted-average shares outstanding under treasury stock method 15,870 16,415 16,202 16,527 Participating securities excluded under two-class method (8 ) (9 ) (42 ) (13 ) Adjusted weighted-average shares outstanding under two-class method 15,862 16,406 16,160 16,514

Commitments and Contingencies C

Commitments and Contingencies Commitments to Purchase (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments to Purchase Aircraft [Abstract]
Long-term Purchase Commitment	As of September 30, 2017 , the Company had firm commitments to purchase the following aircraft: Aircraft Type Number of Aircraft Under Contract Airbus A319 3 Airbus A320 17

Commitments and Contingencies P

Commitments and Contingencies Payments Related to Commitments to Purchase (Tables)	9 Months Ended
	Sep. 30, 2017
Payments Related to Commitments to Purchase [Abstract]
Long-term Purchase Commitment [Table Text Block]	Future minimum fixed payments for the Company's commitments related to the acquisition of aircraft (including aircraft lease obligations), airport fees under use and lease agreements, and other operating lease obligations are as follows as of September 30, 2017 (in thousands): As of September 30, 2017 Remaining in 2017 $ 141,093 2018 140,702 2019 113,873 2020 76,016 2021 34,723 Thereafter 231,358 Total commitments $ 737,765 Contingencies The Company is subject to certain 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.

Summary of Significant Accoun25

Summary of Significant Accounting Policies Policies (Details) $ in Millions	Sep. 30, 2017USD ($)
Accounting Standards Update 2014-09 [Member]
Adjustments for New Accounting Pronouncements [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Expected Increase (Decrease) in Passenger Revenue	$ 500

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Flight equipment, including pre-delivery deposits	$ 1,634,835	$ 1,377,829
Computer Hardware and Software	119,658	101,850
Other Property and Equipment	101,121	81,786
Total property and equipment	1,855,614	1,561,465
Less accumulated depreciation and amortization	523,816	466,151
Property and equipment, net	$ 1,331,798	$ 1,095,314

Long-Term Debt Long-Term Debt -

Long-Term Debt Long-Term Debt - Components of Long-Term Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Notes Payable	$ 1,017,048	$ 813,178
Secured Long-term Debt, Noncurrent	1,011,564	808,274
Less current maturities	165,837	86,226
Long-term debt, net of current maturities and related costs	845,727	722,048
Fixed Rate Notes Payable Through 2020
Debt Instrument [Line Items]
Notes Payable	465,527	465,748
Variable Rate Notes Payable Through 2027 [Member]
Debt Instrument [Line Items]
Notes Payable	$ 546,037	$ 342,526
Fixed Rate [Member]
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate, at Point in Time	5.41%	5.41%
Variable Rate [Member]
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate, at Point in Time	3.25%	3.16%

Long-Term Debt (Detail)

Long-Term Debt (Detail) - USD ($) $ in Thousands	Oct. 01, 2017	Sep. 30, 2017	Dec. 31, 2016
Line of Credit Facility, Borrowing Capacity, Description		56
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year		$ 25,000
Long-term Debt, Maturities, Repayments of Principal in Year Five		46,100
Long-term Debt, Maturities, Repayments of Principal after Year Five		108,900
Debt Instrument, Face Amount		236,500
Secured Long-term Debt, Noncurrent		1,011,564	$ 808,274
Long-term Debt, Maturities, Repayments of Principal in Year Two		218,300
Long-term Debt, Maturities, Repayments of Principal in Year Three		540,000
Long-term Debt, Maturities, Repayments of Principal in Year Four		$ 73,400
Debt Instrument, Basis Spread on Variable Rate		1.62%
Airbus A320 Aircraft Series [Member]
Line of Credit Facility, Collateral		six
Debt Instrument, Collateral		12
Subsequent Event [Member]
Secured Long-term Debt, Noncurrent	$ 68,000
Debt Instrument, Basis Spread on Variable Rate	1.45%
Subsequent Event [Member] | Airbus A320 Aircraft Series [Member]
Debt Instrument, Collateral	2

Long-Term Debt Schedule of Ma29

Long-Term Debt Schedule of Maturities of Long-Term Debt (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Line of Credit Facility, Interest Rate During Period	1.85%
Secured Debt	$ 56,000
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year	25,000
Long-term Debt, Maturities, Repayments of Principal in Year Two	218,300
Long-term Debt, Maturities, Repayments of Principal in Year Three	540,000
Long-term Debt, Maturities, Repayments of Principal in Year Four	73,400
Long-term Debt, Maturities, Repayments of Principal in Year Five	46,100
Long-term Debt, Maturities, Repayments of Principal after Year Five	108,900
Long-term Debt, Fair Value	$ 1,011,564	$ 808,274
Airbus A320 Aircraft Series [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Collateral	six

Fair Value Measurements (Detail

Fair Value Measurements (Detail) - Fair Value Measurements at Reporting Date Using - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Measurements, Recurring
Available-for-sale Securities	$ 458,163	$ 417,128
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Available-for-sale Securities	21,112	123
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Available-for-sale Securities	437,051	417,005
Short-term Investments | Fair Value, Measurements, Recurring
Available-for-sale Securities	351,519	269,269
Short-term Investments | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Available-for-sale Securities	0	0
Short-term Investments | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Available-for-sale Securities	351,519	269,269
Short-term Investments | Fair Value, Measurements, Recurring | Commercial paper
Available-for-sale Securities	83,051	108,372
Short-term Investments | Fair Value, Measurements, Recurring | Commercial paper | Fair Value, Inputs, Level 1
Available-for-sale Securities	0	0
Short-term Investments | Fair Value, Measurements, Recurring | Commercial paper | Fair Value, Inputs, Level 2
Available-for-sale Securities	83,051	108,372
Short-term Investments | Fair Value, Measurements, Recurring | Federal agency debt securities
Available-for-sale Securities	28,432	3,895
Short-term Investments | Fair Value, Measurements, Recurring | Federal agency debt securities | Fair Value, Inputs, Level 1
Available-for-sale Securities	0	0
Short-term Investments | Fair Value, Measurements, Recurring | Federal agency debt securities | Fair Value, Inputs, Level 2
Available-for-sale Securities	28,432	3,895
Short-term Investments | Fair Value, Measurements, Recurring | Municipal debt securities
Available-for-sale Securities	152,369	78,826
Short-term Investments | Fair Value, Measurements, Recurring | Municipal debt securities | Fair Value, Inputs, Level 1
Available-for-sale Securities	0	0
Short-term Investments | Fair Value, Measurements, Recurring | Municipal debt securities | Fair Value, Inputs, Level 2
Available-for-sale Securities	152,369	78,826
Short-term Investments | Fair Value, Measurements, Recurring | Corporate debt securities
Available-for-sale Securities	84,667	76,570
Short-term Investments | Fair Value, Measurements, Recurring | Corporate debt securities | Fair Value, Inputs, Level 1
Available-for-sale Securities	0	0
Short-term Investments | Fair Value, Measurements, Recurring | Corporate debt securities | Fair Value, Inputs, Level 2
Available-for-sale Securities	84,667	76,570
Short-term Investments | Fair Value, Measurements, Recurring | US Treasury Securities
Available-for-sale Securities	3,000	1,606
Short-term Investments | Fair Value, Measurements, Recurring | US Treasury Securities | Fair Value, Inputs, Level 1
Available-for-sale Securities	0	0
Short-term Investments | Fair Value, Measurements, Recurring | US Treasury Securities | Fair Value, Inputs, Level 2
Available-for-sale Securities	3,000	1,606
Long Term Investments | Municipal debt securities | Fair Value, Inputs, Level 1
Available-for-sale Securities	0	0
Long Term Investments | Municipal debt securities | Fair Value, Inputs, Level 2
Available-for-sale Securities	0	72,623
Long Term Investments | Fair Value, Measurements, Recurring
Available-for-sale Securities	77,388	126,494
Long Term Investments | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Available-for-sale Securities	0	0
Long Term Investments | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Available-for-sale Securities	77,388	126,494
Long Term Investments | Fair Value, Measurements, Recurring | Federal agency debt securities
Available-for-sale Securities	5,771	24,160
Long Term Investments | Fair Value, Measurements, Recurring | Federal agency debt securities | Fair Value, Inputs, Level 1
Available-for-sale Securities	0	0
Long Term Investments | Fair Value, Measurements, Recurring | Federal agency debt securities | Fair Value, Inputs, Level 2
Available-for-sale Securities	5,771	24,160
Long Term Investments | Fair Value, Measurements, Recurring | Municipal debt securities
Available-for-sale Securities	0	72,623
Long Term Investments | Fair Value, Measurements, Recurring | Corporate debt securities
Available-for-sale Securities	71,142	25,048
Long Term Investments | Fair Value, Measurements, Recurring | Corporate debt securities | Fair Value, Inputs, Level 1
Available-for-sale Securities	0	0
Long Term Investments | Fair Value, Measurements, Recurring | Corporate debt securities | Fair Value, Inputs, Level 2
Available-for-sale Securities	71,142	25,048
Long Term Investments | Fair Value, Measurements, Recurring | US Treasury Securities
Available-for-sale Securities	0	3,003
Long Term Investments | Fair Value, Measurements, Recurring | US Treasury Securities | Fair Value, Inputs, Level 1
Available-for-sale Securities	0	0
Long Term Investments | Fair Value, Measurements, Recurring | US Treasury Securities | Fair Value, Inputs, Level 2
Available-for-sale Securities	0	3,003
Long Term Investments | Fair Value, Measurements, Recurring | Derivative Financial Instruments, Assets
Available-for-sale Securities	0	1,660
Long Term Investments | Fair Value, Measurements, Recurring | Derivative Financial Instruments, Assets | Fair Value, Inputs, Level 1
Available-for-sale Securities	0	0
Long Term Investments | Fair Value, Measurements, Recurring | Derivative Financial Instruments, Assets | Fair Value, Inputs, Level 2
Available-for-sale Securities	475	1,660
Cash Equivalents [Member] | Fair Value, Measurements, Recurring
Cash Equivalents	29,256	21,365
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Cash Equivalents	21,112	123
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Cash Equivalents	8,144	21,242
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | US Treasury Bonds
Cash Equivalents	21,112	123
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | US Treasury Bonds | Fair Value, Inputs, Level 1
Cash Equivalents	21,112	123
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | US Treasury Bonds | Fair Value, Inputs, Level 2
Cash Equivalents	0	0
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Commercial paper
Cash Equivalents	3,594	0
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Commercial paper | Fair Value, Inputs, Level 1
Cash Equivalents	0	0
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Commercial paper | Fair Value, Inputs, Level 2
Cash Equivalents	3,594	0
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Federal agency debt securities
Cash Equivalents	0	19,399
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Federal agency debt securities | Fair Value, Inputs, Level 1
Cash Equivalents	0	0
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Federal agency debt securities | Fair Value, Inputs, Level 2
Cash Equivalents	0	19,399
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Municipal debt securities
Cash Equivalents	0	1,843
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Municipal debt securities | Fair Value, Inputs, Level 1
Cash Equivalents	0	0
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Municipal debt securities | Fair Value, Inputs, Level 2
Cash Equivalents	$ 0	$ 1,843

Fair Value Measurements Estimat

Fair Value Measurements Estimated Fair Value of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured Long-term Debt, Noncurrent	$ 1,011,564	$ 808,274
Notes Payable	1,017,048	813,178
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured Long-term Debt, Noncurrent	994,295	808,871
Publicly Held Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured Long-term Debt, Noncurrent	451,536	452,179
Publicly Held Debt | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured Long-term Debt, Noncurrent	467,340	468,005
Non-Publicly Held Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured Long-term Debt, Noncurrent	565,512	360,999
Non-Publicly Held Debt | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured Long-term Debt, Noncurrent	$ 526,955	$ 340,866

Derivative Instruments Derivati

Derivative Instruments Derivative Instruments - Textuals (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Derivative [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	$ (193)	$ (208)	$ (749)	$ (533)
Reclassification of derivative gains into Other revenue	175	$ 247	703	$ 756
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			$ 0
Airbus A320 Aircraft Series
Derivative [Line Items]
Debt Instrument, Collateral			12
Fair Value, Measurements, Recurring
Derivative [Line Items]
Available-for-sale Securities	458,163		$ 458,163		$ 417,128
Long Term Investments | Fair Value, Measurements, Recurring
Derivative [Line Items]
Available-for-sale Securities	77,388		77,388		126,494
Derivative Financial Instruments, Assets | Long Term Investments | Fair Value, Measurements, Recurring
Derivative [Line Items]
Available-for-sale Securities	$ 0		$ 0		$ 1,660
Foreign Debt Collateral [Member] | Airbus A320 Aircraft Series
Derivative [Line Items]
Debt Instrument, Collateral			12

Stockholders' Equity (Detail)

Stockholders' Equity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Dividends Payable, Amount Per Share	$ 2.10
Stock Repurchased During Period, Shares	604,497	369,997
Treasury Stock Acquired, Average Cost Per Share	$ 142.66	$ 166.70
Stock Repurchased During Period, Value	$ 86,240	$ 61,679
Dividends	$ 34,500

Earnings per Share (Detail) - E

Earnings per Share (Detail) - Earnings Per Share - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	129,989		51,439
Basic:
Net income attributable to Allegiant Travel Company (in Dollars)	$ 22,293	$ 45,453	$ 112,400	$ 178,280
Less: Net income allocated to participating securities (in Dollars)	(315)	(298)	(1,747)	(1,074)
Net income attributable to common stock (in Dollars)	$ 21,978	$ 45,155	$ 110,653	$ 177,206
Net income per share, basic (in Dollars per share)	$ 1.39	$ 2.76	$ 6.85	$ 10.74
Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted	$ (315)	$ (297)	$ (1,745)	$ (1,073)
Net Income (Loss) Available to Common Stockholders, Diluted	$ 21,978	$ 45,156	$ 110,655	$ 177,207
Net income per share, diluted (in Dollars per share)	$ 1.39	$ 2.75	$ 6.85	$ 10.73
Weighted-average shares outstanding	15,852,000	16,389,000	16,142,000	16,493,000
Dilutive effect of stock options, restricted stock and stock-settled stock appreciation rights	18,000	26,000	60,000	34,000
Adjusted weighted-average shares outstanding under treasury stock method	15,870,000	16,415,000	16,202,000	16,527,000
Participating securities excluded under two-class method	(8,000)	(9,000)	(42,000)	(13,000)
Two-Class Method, Weighted Average Number of Shares Outstanding, Diluted	15,862,000	16,406,000	16,160,000	16,514,000

Commitments and Contingencies (

Commitments and Contingencies (Detail) $ in Thousands	Sep. 30, 2017USD ($)aircraft
Long-term Purchase Commitment [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year	$ 141,093
Unrecorded Unconditional Purchase Obligation, Due within Two Years	140,702
Unrecorded Unconditional Purchase Obligation, Due within Three Years	113,873
Unrecorded Unconditional Purchase Obligation, Due within Four Years	76,016
Unrecorded Unconditional Purchase Obligation, Due within Five Years	34,723
Unrecorded Unconditional Purchase Obligation, Due after Five Years	231,358
Unrecorded Unconditional Purchase Obligation	$ 737,765
Airbus A319
Long-term Purchase Commitment [Line Items]
Number Of Aircraft Committed To Purchase | aircraft	3
Airbus A320
Long-term Purchase Commitment [Line Items]
Number Of Aircraft Committed To Purchase | aircraft	17

Commitments and Contingencies36

Commitments and Contingencies Payments Related to Commitments to Purchase (Details) $ in Thousands	Sep. 30, 2017USD ($)
Payments Related to Commitments to Purchase [Abstract]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year	$ 141,093
Unrecorded Unconditional Purchase Obligation, Due within Two Years	140,702
Unrecorded Unconditional Purchase Obligation, Due within Three Years	113,873
Unrecorded Unconditional Purchase Obligation, Due within Four Years	76,016
Unrecorded Unconditional Purchase Obligation, Due within Five Years	34,723
Unrecorded Unconditional Purchase Obligation, Due after Five Years	231,358
Unrecorded Unconditional Purchase Obligation	$ 737,765

Related Party (Details)

Related Party (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction		$ 0.2	$ 1.4
Lease Termination
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	$ 1.3
Building 1
Related Party Transaction [Line Items]
Related Party Transaction, Description of Transaction	70,000

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events (Details) - USD ($) $ in Thousands	Oct. 01, 2017	Sep. 30, 2017	Dec. 31, 2016
Subsequent Event [Line Items]
Secured Long-term Debt, Noncurrent		$ 1,011,564	$ 808,274
Debt Instrument, Basis Spread on Variable Rate		1.62%
Subsequent Event [Member]
Subsequent Event [Line Items]
Secured Long-term Debt, Noncurrent	$ 68,000
Debt Instrument, Basis Spread on Variable Rate	1.45%
Airbus A320 Aircraft Series [Member]
Subsequent Event [Line Items]
Debt Instrument, Collateral		12
Airbus A320 Aircraft Series [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Debt Instrument, Collateral	2
Purchase Commitment, Description	4
MD-80 Aircraft [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Impaired Assets to be Disposed of by Method Other than Sale, Carrying Value of Asset	$ 40,000