Allegiant Travel (ALGT) 10-Q 31 Jul 17 2017 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 14, 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		16,070,344
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	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2

Consolidated Balance Sheets (Cu

Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Jun. 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	$ 20,040	$ 64,711
Restricted cash	11,423	11,647
Short-term investments	323,117	269,269
Accounts receivable	23,917	40,667
Expendable parts, supplies and fuel, net	17,855	16,797
Prepaid expenses	25,753	16,277
Other current assets	4,809	2,686
TOTAL CURRENT ASSETS	426,914	422,054
Property and equipment, net	1,212,771	1,095,314
Long-term investments	159,769	124,834
Deferred major maintenance, net	28,813	17,347
Deposits and other assets	11,730	12,027
TOTAL ASSETS	1,839,997	1,671,576
CURRENT LIABILITIES:
Accounts payable	18,002	16,010
Accrued liabilities	110,842	96,661
Air traffic liability	237,835	194,001
Current maturities of notes payable, net of related costs	116,387	86,226
TOTAL CURRENT LIABILITIES	483,066	392,898
Long-term debt, net of current maturities and related costs	761,082	722,048
Deferred income taxes	127,631	75,338
Other noncurrent liabilities	8,732	7,670
TOTAL LIABILITIES:	1,380,511	1,197,954
SHAREHOLDERS' EQUITY:
Common stock, par value $.001	23	22
Treasury stock	(606,352)	(517,803)
Additional paid in capital	246,906	238,236
Accumulated other comprehensive loss, net	(1,391)	(230)
Retained earnings	820,300	753,397
TOTAL EQUITY	459,486	473,622
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 1,839,997	$ 1,671,576

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Cash dividends declared per share:	$ 0.70	$ 0.70	$ 1.40	$ 1
OPERATING REVENUE:
Scheduled service revenue	$ 220,615	$ 189,122	$ 432,713	$ 390,728
Ancillary revenue:
Air-related charges	145,405	128,713	276,970	249,643
Third party products	14,304	11,965	27,046	23,223
Total ancillary revenue	159,709	140,678	304,016	272,866
Fixed fee contract revenue	11,029	6,706	22,289	13,507
Other revenue	9,261	8,345	17,434	16,366
Total operating revenue	400,614	344,851	776,452	693,467
OPERATING EXPENSES:
Aircraft fuel	85,387	60,005	170,049	113,663
Salary and benefits	92,221	68,553	188,519	137,761
Station operations	38,998	33,328	70,830	64,061
Maintenance and repairs	28,645	29,261	58,740	55,753
Depreciation and amortization	30,129	25,396	60,678	50,081
Sales and marketing	12,861	5,317	22,859	11,125
Aircraft lease rentals	2,400	219	2,564	452
Other	24,777	18,296	44,129	34,968
Total operating expenses	315,418	240,375	618,368	467,864
OPERATING INCOME	85,196	104,476	158,084	225,603
OTHER (INCOME) EXPENSE:
Interest expense	8,889	7,390	17,291	14,629
Interest income	(1,475)	(710)	(2,739)	(1,321)
Other, net	493	300	854	663
Total other expense	6,921	6,380	13,698	12,645
INCOME BEFORE INCOME TAXES	78,275	98,096	144,386	212,958
PROVISION FOR INCOME TAXES	29,800	37,249	54,279	80,131
NET INCOME	$ 48,475	$ 60,847	$ 90,107	$ 132,827
Earnings per share to common stockholders:
Basic	$ 2.94	$ 3.68	$ 5.44	$ 7.98
Diluted	$ 2.94	$ 3.68	$ 5.43	$ 7.97
Shares used for computation:
Basic	16,198,000	16,420,000	16,290,000	16,549,000
Diluted	16,220,000	16,442,000	16,317,000	16,574,000

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net income	$ 48,475	$ 60,847	$ 90,107	$ 132,827
Other comprehensive (loss) income:
Change in available for sale securities, net of tax	(2)	148	222	439
Foreign currency translation adjustments	(215)	43	(298)	(63)
Change in derivatives, net of tax	(341)	6	(556)	(325)
Reclassification of derivative gains into Other revenue	(240)	(245)	(529)	(510)
Total other comprehensive loss	(798)	(48)	(1,161)	(459)
TOTAL COMPREHENSIVE INCOME	$ 47,677	$ 60,799	$ 88,946	$ 132,368

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
OPERATING ACTIVITIES:
Net income	$ 90,107	$ 132,827
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	60,678	50,081
Loss/(gain) on aircraft and other equipment disposals	4,901	(472)
Provision for obsolescence of expendable parts, supplies and fuel	1,753	1,043
Amortization of deferred financing costs	775	745
Share-based compensation expense	7,249	3,002
Deferred income taxes	51,995	2,753
Changes in certain assets and liabilities:
(Increase) decrease in accounts receivable	16,572	(227)
(Increase) decrease in prepaid expenses	(9,476)	584
Increase (decrease) in accounts payable	2,263	3,505
Increase (decrease) in accrued liabilities	10,382	23,888
Increase (decrease) in air traffic liability	43,834	42,731
Increase Decrease for Deferred Major Maintenance, Net	(14,331)	(2,891)
Other, net	(3,558)	(1,470)
Net cash provided by operating activities	263,144	256,099
INVESTING ACTIVITIES:
Purchase of investment securities	(242,895)	(197,611)
Proceeds from maturities of investment securities	154,334	180,078
Aircraft pre-delivery deposits	(63,468)	0
Purchase of property and equipment, including capitalized interest	(118,846)	(105,177)
Other investing activities	1,352	3,773
Net cash used in investing activities	(269,523)	(118,937)
FINANCING ACTIVITIES:
Cash dividends paid to shareholders	(23,204)	(44,355)
Proceeds from the issuance of long-term debt	134,540	28,000
Repurchase of common stock	(84,940)	(63,319)
Principal payments on long-term debt	(64,876)	(39,210)
Other financing activities	188	293
Net cash used in financing activities	(38,292)	(118,591)
Net change in cash and cash equivalents	(44,671)	18,571
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	64,711	87,112
CASH AND CASH EQUIVALENTS AT END OF PERIOD	20,040	105,683
CASH PAYMENTS FOR:
Interest paid, net of amount capitalized	16,001	11,936
Income taxes paid, net of refunds	$ 0	$ 59,928

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 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 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 for which the entity expects to be entitled in exchange for those goods or services. Under the new standard, revenue related to certain air-related ancillary fees 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. In addition, change 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 new standard is effective for annual and interim periods beginning after December 15, 2017, and the Company will adopt effective January 1, 2018. The Company continues to evaluate the impact on its financial statements of adopting this new accounting standard and believes that adoption will have little effect on earnings, although the classification of certain air-related ancillary fees, as described above, 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	6 Months Ended
	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure	Property and Equipment Property and equipment (in thousands): As of June 30, 2017 As of December 31, 2016 Flight equipment, including pre-delivery deposits $ 1,518,072 $ 1,377,829 Computer hardware and software 113,321 101,850 Other property and equipment 88,001 81,786 Total property and equipment 1,719,394 1,561,465 Less accumulated depreciation and amortization (506,623 ) (466,151 ) Property and equipment, net $ 1,212,771 $ 1,095,314

Long-Term Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt Long-term debt (in thousands): As of June 30, 2017 As of December 31, 2016 Fixed-rate notes payable due through 2020 $ 465,594 $ 465,748 Variable-rate notes payable due through 2027 411,875 342,526 Total long-term debt, net of related costs 877,469 808,274 Less current maturities, net of related costs 116,387 86,226 Long-term debt, net of current maturities and related costs $ 761,082 $ 722,048 Weighted average fixed-interest rate 5.41 % 5.41 % Weighted average variable-interest rate 3.27 % 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 - $45.8 million ; 2018 - $154.4 million ; 2019 - $530.0 million ; 2020 - $64.5 million ; 2021 - $37.2 million ; and $45.6 million thereafter. Secured Debt In the first six months of 2017, the Company borrowed $134.5 million under loan agreements secured by nine Airbus A320 series aircraft. The notes bear interest at a floating rate based on LIBOR plus a weighted average margin of 1.68 percent and are payable in quarterly installments over five or ten years.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 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 June 30, 2017 As of December 31, 2016 Total Level 1 Level 2 Total Level 1 Level 2 Cash equivalents Municipal debt securities $ 1,568 $ — $ 1,568 $ 1,843 $ — $ 1,843 Money market funds 502 502 — 123 123 — Federal agency debt securities — — — 19,399 — 19,399 Total cash equivalents 2,070 502 1,568 21,365 123 21,242 Short-term Municipal debt securities 143,273 — 143,273 78,826 — 78,826 Commercial paper 96,105 — 96,105 108,372 — 108,372 Corporate debt securities 69,897 — 69,897 76,570 — 76,570 Federal agency debt securities 10,840 — 10,840 3,895 — 3,895 US Treasury Bonds 3,002 — 3,002 1,606 — 1,606 Total short-term 323,117 — 323,117 269,269 — 269,269 Long-term Corporate debt securities 106,134 — 106,134 25,048 — 25,048 Municipal debt securities 29,378 — 29,378 72,623 — 72,623 Federal agency debt securities 24,257 — 24,257 24,160 — 24,160 Derivative instruments 780 — 780 1,660 — 1,660 US Treasury Bonds — — — 3,003 — 3,003 Total long-term 160,549 — 160,549 126,494 — 126,494 Total financial instruments $ 485,736 $ 502 $ 485,234 $ 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 June 30, 2017 As of December 31, 2016 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Hierarchy Level Publicly held debt $ 451,750 $ 469,820 $ 452,179 $ 468,005 2 Non-publicly held debt 430,631 402,628 360,999 340,866 3 Total long-term debt $ 882,381 $ 872,448 $ 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	6 Months Ended
	Jun. 30, 2017
Derivative Instruments [Abstract]
Derivative Instruments and Hedging Activities Disclosure	Derivative Instruments The Company entered into a foreign currency swap 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 six months ended June 30, 2017 , the net change in fair value recorded in accumulated other comprehensive income related to an unrealized loss on the hedge was $0.6 million compared to $0.3 million for the six months ended June 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 each of the six months ended June 30, 2017 and June 30, 2016 , the Company realized $0.5 million in gains from its cash flow hedge into Other revenue. As of June 30, 2017 , the Company expects $0.5 million to be reclassified from Other comprehensive income into Other revenue within the next 12 months. At June 30, 2017 , the fair value of the Company's derivative instrument was $0.8 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	6 Months Ended
	Jun. 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. Share repurchases consisted of the following during the periods indicated: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Shares repurchased (not in thousands) 589,057 55,148 604,497 369,997 Average price per share $ 142.16 $ 139.08 $ 142.66 $ 166.70 Total (in thousands) $ 83,740 $ 7,670 $ 86,240 $ 61,679 During the six months ended June 30, 2017 , the Company declared and paid recurring cash dividends of $1.40 per share, or $23.2 million .

Earnings per Share

Earnings per Share	6 Months Ended
	Jun. 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 six months ended June 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 June 30, Six Months Ended June 30, 2017 2016 2017 2016 Basic: Net income $ 48,475 $ 60,847 $ 90,107 $ 132,827 Less net income allocated to participating securities (780 ) (350 ) (1,461 ) (758 ) Net income attributable to common stock $ 47,695 $ 60,497 $ 88,646 $ 132,069 Net income per share, basic $ 2.94 $ 3.68 $ 5.44 $ 7.98 Weighted-average shares outstanding 16,198 16,420 16,290 16,549 Diluted: Net income $ 48,475 $ 60,847 $ 90,107 $ 132,827 Less net income allocated to participating securities (779 ) (350 ) (1,459 ) (757 ) Net income attributable to common stock $ 47,696 $ 60,497 $ 88,648 $ 132,070 Net income per share, diluted $ 2.94 $ 3.68 $ 5.43 $ 7.97 Weighted-average shares outstanding 16,198 16,420 16,290 16,549 Dilutive effect of stock options and restricted stock 71 36 92 42 Adjusted weighted-average shares outstanding under treasury stock method 16,269 16,456 16,382 16,591 Participating securities excluded under two-class method (49 ) (14 ) (65 ) (17 ) Adjusted weighted-average shares outstanding under two-class method 16,220 16,442 16,317 16,574 For the three and six months ended June 30, 2017 , anti-dilutive shares excluded from the calculation of earnings per share were 62,605 and 45,940 (shares not in thousands), respectively.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies As of June 30, 2017 , the Company had firm commitments to purchase the following aircraft: Aircraft Type Number of Aircraft Under Contract Airbus A319 4 Airbus A320 21 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 June 30, 2017 (in thousands): As of June 30, 2017 Remaining in 2017 $ 262,010 2018 139,079 2019 112,040 2020 74,306 2021 33,047 Thereafter 230,593 Total commitments $ 851,075 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	6 Months Ended
	Jun. 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 six months ended June 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 - aircraft	6 Months Ended
	Jun. 30, 2017	Jul. 01, 2017
Subsequent Event [Line Items]
Subsequent Events [Text Block]	Subsequent Events In July 2017, the Company borrowed $68.0 million under loan agreements secured by two Airbus A320 series aircraft. The notes bear interest at a floating rate based on LIBOR plus an average margin of 1.50 percent and are payable in quarterly installments through July 2027.
Subsequent Event [Member]
Subsequent Event [Line Items]
Number Of Aircraft Committed To Purchase		2

Summary of Significant Accoun16

Summary of Significant Accounting Policies - (Policies)	6 Months Ended
	Jun. 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 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 for which the entity expects to be entitled in exchange for those goods or services. Under the new standard, revenue related to certain air-related ancillary fees 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. In addition, change 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 new standard is effective for annual and interim periods beginning after December 15, 2017, and the Company will adopt effective January 1, 2018. The Company continues to evaluate the impact on its financial statements of adopting this new accounting standard and believes that adoption will have little effect on earnings, although the classification of certain air-related ancillary fees, as described above, 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)	6 Months Ended
	Jun. 30, 2017
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	Property and equipment (in thousands): As of June 30, 2017 As of December 31, 2016 Flight equipment, including pre-delivery deposits $ 1,518,072 $ 1,377,829 Computer hardware and software 113,321 101,850 Other property and equipment 88,001 81,786 Total property and equipment 1,719,394 1,561,465 Less accumulated depreciation and amortization (506,623 ) (466,151 ) Property and equipment, net $ 1,212,771 $ 1,095,314

Long-Term Debt (Tables)

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Summary of Long-Term Debt	Long-term debt (in thousands): As of June 30, 2017 As of December 31, 2016 Fixed-rate notes payable due through 2020 $ 465,594 $ 465,748 Variable-rate notes payable due through 2027 411,875 342,526 Total long-term debt, net of related costs 877,469 808,274 Less current maturities, net of related costs 116,387 86,226 Long-term debt, net of current maturities and related costs $ 761,082 $ 722,048 Weighted average fixed-interest rate 5.41 % 5.41 % Weighted average variable-interest rate 3.27 % 3.16 %

Long-Term Debt Schedule of Matu

Long-Term Debt Schedule of Maturities of Long-Term Debt (Tables)	6 Months Ended
	Jun. 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 - $45.8 million ; 2018 - $154.4 million ; 2019 - $530.0 million ; 2020 - $64.5 million ; 2021 - $37.2 million ; and $45.6 million thereafter.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 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 June 30, 2017 As of December 31, 2016 Total Level 1 Level 2 Total Level 1 Level 2 Cash equivalents Municipal debt securities $ 1,568 $ — $ 1,568 $ 1,843 $ — $ 1,843 Money market funds 502 502 — 123 123 — Federal agency debt securities — — — 19,399 — 19,399 Total cash equivalents 2,070 502 1,568 21,365 123 21,242 Short-term Municipal debt securities 143,273 — 143,273 78,826 — 78,826 Commercial paper 96,105 — 96,105 108,372 — 108,372 Corporate debt securities 69,897 — 69,897 76,570 — 76,570 Federal agency debt securities 10,840 — 10,840 3,895 — 3,895 US Treasury Bonds 3,002 — 3,002 1,606 — 1,606 Total short-term 323,117 — 323,117 269,269 — 269,269 Long-term Corporate debt securities 106,134 — 106,134 25,048 — 25,048 Municipal debt securities 29,378 — 29,378 72,623 — 72,623 Federal agency debt securities 24,257 — 24,257 24,160 — 24,160 Derivative instruments 780 — 780 1,660 — 1,660 US Treasury Bonds — — — 3,003 — 3,003 Total long-term 160,549 — 160,549 126,494 — 126,494 Total financial instruments $ 485,736 $ 502 $ 485,234 $ 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 June 30, 2017 As of December 31, 2016 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Hierarchy Level Publicly held debt $ 451,750 $ 469,820 $ 452,179 $ 468,005 2 Non-publicly held debt 430,631 402,628 360,999 340,866 3 Total long-term debt $ 882,381 $ 872,448 $ 813,178 $ 808,871

Stockholders' Equity Repurchase

Stockholders' Equity Repurchases (Tables)	6 Months Ended
	Jun. 30, 2017
Equity, Class of Treasury Stock [Line Items]
Treasury Stock [Text Block]	Share repurchases consisted of the following during the periods indicated: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 Shares repurchased (not in thousands) 589,057 55,148 604,497 369,997 Average price per share $ 142.16 $ 139.08 $ 142.66 $ 166.70 Total (in thousands) $ 83,740 $ 7,670 $ 86,240 $ 61,679

Earnings per Share (Tables)

Earnings per Share (Tables)	6 Months Ended
	Jun. 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 June 30, Six Months Ended June 30, 2017 2016 2017 2016 Basic: Net income $ 48,475 $ 60,847 $ 90,107 $ 132,827 Less net income allocated to participating securities (780 ) (350 ) (1,461 ) (758 ) Net income attributable to common stock $ 47,695 $ 60,497 $ 88,646 $ 132,069 Net income per share, basic $ 2.94 $ 3.68 $ 5.44 $ 7.98 Weighted-average shares outstanding 16,198 16,420 16,290 16,549 Diluted: Net income $ 48,475 $ 60,847 $ 90,107 $ 132,827 Less net income allocated to participating securities (779 ) (350 ) (1,459 ) (757 ) Net income attributable to common stock $ 47,696 $ 60,497 $ 88,648 $ 132,070 Net income per share, diluted $ 2.94 $ 3.68 $ 5.43 $ 7.97 Weighted-average shares outstanding 16,198 16,420 16,290 16,549 Dilutive effect of stock options and restricted stock 71 36 92 42 Adjusted weighted-average shares outstanding under treasury stock method 16,269 16,456 16,382 16,591 Participating securities excluded under two-class method (49 ) (14 ) (65 ) (17 ) Adjusted weighted-average shares outstanding under two-class method 16,220 16,442 16,317 16,574

Commitments and Contingencies C

Commitments and Contingencies Commitments to Purchase (Tables)	6 Months Ended
	Jun. 30, 2017
Commitments to Purchase Aircraft [Abstract]
Long-term Purchase Commitment	As of June 30, 2017 , the Company had firm commitments to purchase the following aircraft: Aircraft Type Number of Aircraft Under Contract Airbus A319 4 Airbus A320 21

Commitments and Contingencies P

Commitments and Contingencies Payments Related to Commitments to Purchase (Tables)	6 Months Ended
	Jun. 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 June 30, 2017 (in thousands): As of June 30, 2017 Remaining in 2017 $ 262,010 2018 139,079 2019 112,040 2020 74,306 2021 33,047 Thereafter 230,593 Total commitments $ 851,075 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.

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Flight equipment, including pre-delivery deposits	$ 1,518,072	$ 1,377,829
Computer Hardware and Software	113,321	101,850
Other property and equipment	88,001	81,786
Total property and equipment	1,719,394	1,561,465
Less accumulated depreciation and amortization	506,623	466,151
Property and equipment, net	$ 1,212,771	$ 1,095,314

Long-Term Debt Long-Term Debt -

Long-Term Debt Long-Term Debt - Components of Long-Term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Notes Payable	$ 882,381	$ 813,178
Secured Long-term Debt, Noncurrent	877,469	808,274
Less current maturities	116,387	86,226
Long-term debt, net of current maturities and related costs	761,082	722,048
Fixed Rate Notes Payable Through 2020
Debt Instrument [Line Items]
Notes Payable	465,594	465,748
Variable Rate Notes Payable Through 2027 [Member]
Debt Instrument [Line Items]
Notes Payable	$ 411,875	$ 342,526

Long-Term Debt (Detail)

Long-Term Debt (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year	$ 45,823	$ 45,823
Long-term Debt, Maturities, Repayments of Principal in Year Five	37,232	37,232
Long-term Debt, Maturities, Repayments of Principal after Year Five	45,600	45,600
Debt Instrument, Face Amount	134,500	134,500
Secured Long-term Debt, Noncurrent	877,469	877,469	$ 808,274
Long-term Debt, Maturities, Repayments of Principal in Year Two	154,354	154,354
Long-term Debt, Maturities, Repayments of Principal in Year Three	529,986	529,986
Long-term Debt, Maturities, Repayments of Principal in Year Four	$ 64,474	$ 64,474
Debt Instrument, Basis Spread on Variable Rate		1.68%
Airbus A320 Aircraft Series [Member]
Debt Instrument, Collateral	12	9

Long-Term Debt Schedule of Ma28

Long-Term Debt Schedule of Maturities of Long-Term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year	$ 45,823
Long-term Debt, Maturities, Repayments of Principal in Year Two	154,354
Long-term Debt, Maturities, Repayments of Principal in Year Three	529,986
Long-term Debt, Maturities, Repayments of Principal in Year Four	64,474
Long-term Debt, Maturities, Repayments of Principal in Year Five	37,232
Long-term Debt, Maturities, Repayments of Principal after Year Five	45,600
Long-term Debt, Fair Value	$ 877,469	$ 808,274

Fair Value Measurements (Detail

Fair Value Measurements (Detail) - Fair Value Measurements at Reporting Date Using - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Measurements, Recurring
Available-for-sale Securities	$ 485,736	$ 417,128
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Available-for-sale Securities	502	123
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Available-for-sale Securities	485,234	417,005
Short-term Investments | Fair Value, Measurements, Recurring
Available-for-sale Securities	323,117	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	323,117	269,269
Short-term Investments | Fair Value, Measurements, Recurring | Commercial paper
Available-for-sale Securities	96,105	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	96,105	108,372
Short-term Investments | Fair Value, Measurements, Recurring | Federal agency debt securities
Available-for-sale Securities	10,840	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	10,840	3,895
Short-term Investments | Fair Value, Measurements, Recurring | Municipal debt securities
Available-for-sale Securities	143,273	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	143,273	78,826
Short-term Investments | Fair Value, Measurements, Recurring | Corporate debt securities
Available-for-sale Securities	69,897	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	69,897	76,570
Short-term Investments | Fair Value, Measurements, Recurring | US Treasury Securities
Available-for-sale Securities	3,002	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	3,002	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	29,378	72,623
Long Term Investments | Fair Value, Measurements, Recurring
Available-for-sale Securities	160,549	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	160,549	126,494
Long Term Investments | Fair Value, Measurements, Recurring | Federal agency debt securities
Available-for-sale Securities	24,257	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	24,257	24,160
Long Term Investments | Fair Value, Measurements, Recurring | Municipal debt securities
Available-for-sale Securities	29,378	72,623
Long Term Investments | Fair Value, Measurements, Recurring | Corporate debt securities
Available-for-sale Securities	106,134	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	106,134	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	1,000	2,000
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	780	1,660
Cash Equivalents [Member] | Fair Value, Measurements, Recurring
Cash Equivalents	2,070	21,365
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Cash Equivalents	502	123
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Cash Equivalents	1,568	21,242
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | US Treasury Bonds
Cash Equivalents	502	123
Cash Equivalents [Member] | Fair Value, Measurements, Recurring | US Treasury Bonds | Fair Value, Inputs, Level 1
Cash Equivalents	502	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 | 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	1,568	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	$ 1,568	$ 1,843

Fair Value Measurements Estimat

Fair Value Measurements Estimated Fair Value of Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured Long-term Debt, Noncurrent	$ 877,469	$ 808,274
Notes Payable	882,381	813,178
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured Long-term Debt, Noncurrent	872,448	808,871
Publicly Held Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured Long-term Debt, Noncurrent	451,750	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	469,820	468,005
Non-Publicly Held Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured Long-term Debt, Noncurrent	430,631	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	$ 402,628	$ 340,866

Derivative Instruments Derivati

Derivative Instruments Derivative Instruments - Textuals (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	$ (341)	$ 6	$ (556)	$ (325)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	$ 240	$ 245	529	$ 510
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			$ 0
Airbus A320 Aircraft Series
Derivative [Line Items]
Debt Instrument, Collateral	12		9

Stockholders' Equity (Detail)

Stockholders' Equity (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Stock Repurchased During Period, Shares	589,057	55,148	604,497	369,997
Treasury Stock Acquired, Average Cost Per Share	$ 142.16	$ 139.08	$ 142.66	$ 166.70
Stock Repurchased During Period, Value	$ 83,740	$ 7,670	$ 86,240	$ 61,679
Dividends			$ 23,204
Common Stock, Dividends, Per Share, Cash Paid			$ 1.40

Earnings per Share (Detail) - E

Earnings per Share (Detail) - Earnings Per Share - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	62,605		45,940
Basic:
Net income attributable to Allegiant Travel Company (in Dollars)	$ 48,475	$ 60,847	$ 90,107	$ 132,827
Less: Net income allocated to participating securities (in Dollars)	(780)	(350)	(1,461)	(758)
Net income attributable to common stock (in Dollars)	$ 47,695	$ 60,497	$ 88,646	$ 132,069
Net income per share, basic (in Dollars per share)	$ 2.94	$ 3.68	$ 5.44	$ 7.98
Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted	$ (779)	$ (350)	$ (1,459)	$ (757)
Net Income (Loss) Available to Common Stockholders, Diluted	$ 47,696	$ 60,497	$ 88,648	$ 132,070
Net income per share, diluted (in Dollars per share)	$ 2.94	$ 3.68	$ 5.43	$ 7.97
Weighted-average shares outstanding	16,198,000	16,420,000	16,290,000	16,549,000
Dilutive effect of stock options, restricted stock and stock-settled stock appreciation rights	71,000	36,000	92,000	42,000
Adjusted weighted-average shares outstanding under treasury stock method	16,269,000	16,456,000	16,382,000	16,591,000
Participating securities excluded under two-class method	(49,000)	(14,000)	(65,000)	(17,000)
Two-Class Method, Weighted Average Number of Shares Outstanding, Diluted	16,220,000	16,442,000	16,317,000	16,574,000

Commitments and Contingencies (

Commitments and Contingencies (Detail) $ in Thousands	Jun. 30, 2017USD ($)aircraft
Long-term Purchase Commitment [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year	$ 262,010
Unrecorded Unconditional Purchase Obligation, Due within Two Years	139,079
Unrecorded Unconditional Purchase Obligation, Due within Three Years	112,040
Unrecorded Unconditional Purchase Obligation, Due within Four Years	74,306
Unrecorded Unconditional Purchase Obligation, Due within Five Years	33,047
Unrecorded Unconditional Purchase Obligation, Due after Five Years	230,593
Unrecorded Unconditional Purchase Obligation	$ 851,075
Airbus A319
Long-term Purchase Commitment [Line Items]
Number Of Aircraft Committed To Purchase | aircraft	4
Airbus A320
Long-term Purchase Commitment [Line Items]
Number Of Aircraft Committed To Purchase | aircraft	21

Commitments and Contingencies35

Commitments and Contingencies Payments Related to Commitments to Purchase (Details) $ in Thousands	Jun. 30, 2017USD ($)
Payments Related to Commitments to Purchase [Abstract]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year	$ 262,010
Unrecorded Unconditional Purchase Obligation, Due within Two Years	139,079
Unrecorded Unconditional Purchase Obligation, Due within Three Years	112,040
Unrecorded Unconditional Purchase Obligation, Due within Four Years	74,306
Unrecorded Unconditional Purchase Obligation, Due within Five Years	33,047
Unrecorded Unconditional Purchase Obligation, Due after Five Years	230,593
Unrecorded Unconditional Purchase Obligation	$ 851,075

Related Party (Details)

Related Party (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction		$ 200	$ 1,400
Lease Termination
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	$ 1,300
Building 1
Related Party Transaction [Line Items]
Related Party Transaction, Description of Transaction	70,000

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events (Details) $ in Thousands	Jul. 31, 2017	Jun. 30, 2017USD ($)	Jul. 01, 2017USD ($)aircraft	Dec. 31, 2016USD ($)
Subsequent Event [Line Items]
Secured Long-term Debt, Noncurrent		$ 877,469		$ 808,274
Debt Instrument, Basis Spread on Variable Rate		1.68%
Subsequent Event [Member]
Subsequent Event [Line Items]
Number Of Aircraft Committed To Purchase | aircraft			2
Debt Instrument, Basis Spread on Variable Rate	1.50%
Due September 2027 [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Secured Long-term Debt, Noncurrent			$ 68,000