Frontier (ULCC) 10-Q 13 May 21 2021 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2021	May 07, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-40304
Entity Registrant Name	Frontier Group Holdings, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-3681866
Entity Address, Address Line One	4545 Airport Way
Entity Address, City or Town	Denver
Entity Address, State or Province	CO
Entity Address, Postal Zip Code	80239
City Area Code	720
Local Phone Number	374-4200
Title of 12(b) Security	Common Stock, $0.001 par value
Security Exchange Name	NASDAQ
Trading Symbol	ULCC
Entity Current Reporting Status	No
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		215,427,043
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001670076
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current Assets
Cash and cash equivalents	$ 429,000	$ 378,000
Accounts receivable, net	48,000	28,000
Supplies, net	20,000	18,000
Other current assets	223,000	226,000
Total current assets	720,000	650,000
Property and equipment, net	177,000	176,000
Operating lease right-of-use assets	2,292,000	2,250,000
Pre-delivery deposits for flight equipment	212,000	224,000
Aircraft maintenance deposits	86,000	82,000
Intangible assets, net	29,000	29,000
Other assets	164,000	143,000
Total assets	3,680,000	3,554,000
Current liabilities
Accounts payable	79,000	71,000
Air traffic liability	230,000	135,000
Frequent flyer liability	12,000	13,000
Current maturities of long-term debt, net	110,000	101,000
Current maturities of operating leases	423,000	416,000
Other current liabilities	369,000	267,000
Total current liabilities	1,223,000	1,003,000
Long-term debt, net	242,000	247,000
Long-term operating leases	1,881,000	1,848,000
Long-term frequent flyer liability	50,000	50,000
Other long-term liabilities	65,000	96,000
Total liabilities	3,461,000	3,244,000
Commitments and contingencies
Stockholders' equity
Common stock, no par value, stated value of $0.001 per share, with 200,416,799 and 199,438,098 shares issued and outstanding as of March 31, 2021 and December 31, 2020, respectively	0	0
Additional paid-in capital	60,000	60,000
Retained earnings	170,000	261,000
Accumulated other comprehensive income (loss)	(11,000)	(11,000)
Total stockholders’ equity	219,000	310,000
Total liabilities and stockholders’ equity	$ 3,680,000	$ 3,554,000

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Common stock, stated value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares issued (in shares)	200,416,799	199,438,098
Common stock outstanding (in shares)	200,416,799	199,438,098
Cash and cash equivalents	$ 429	$ 378

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating revenues:
Total operating revenues	$ 271,000	$ 544,000
Operating expenses:
Aircraft fuel	84,000	204,000
Salaries, wages and benefits	139,000	148,000
Aircraft rent	138,000	103,000
Station operations	70,000	96,000
Sales and marketing	17,000	30,000
Maintenance materials and repairs	26,000	26,000
Depreciation and amortization	8,000	8,000
CARES Act credits	(136,000)	0
Other operating	17,000	35,000
Total operating expenses	363,000	650,000
Operating income (loss)	(92,000)	(106,000)
Other income (expense):
Interest expense	(22,000)	(2,000)
Capitalized interest	1,000	2,000
Interest income and other	0	3,000
Total other income (expense)	(21,000)	3,000
Income (loss) before income taxes	(113,000)	(103,000)
Income tax expense (benefit)	(22,000)	(39,000)
Net income (loss)	$ (91,000)	$ (64,000)
Earnings (loss) per share:
Net earnings (loss) per share, basic (in dollars per share)	$ (0.46)	$ (0.32)
Net earnings (loss) per share, diluted (in dollars per share)	$ (0.46)	$ (0.32)
Passenger
Operating revenues:
Total operating revenues	$ 262,000	$ 528,000
Other
Operating revenues:
Total operating revenues	$ 9,000	$ 16,000

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (91,000)	$ (64,000)
Other comprehensive loss
Unrealized loss from cash flows hedges net of adjustment for dedesignation of fuel hedges, net of tax	0	(26,000)
Other comprehensive income (loss)	0	(26,000)
Comprehensive income (loss)	$ (91,000)	$ (90,000)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net income (loss)	$ (91,000)	$ (64,000)
Deferred income taxes	(22,000)	(36,000)
Depreciation and amortization	8,000	8,000
Gains recognized on sale-leaseback transactions	(15,000)	(17,000)
Warrant liability unrealized loss	20,000	0
Stock-based compensation	3,000	2,000
Losses from de-designated derivative positions	0	(56,000)
Cash flows from derivative instruments, net	0	(42,000)
Cash flows from operating leases	0	17,000
Changes in operating assets and liabilities:
Accounts receivable	(20,000)	31,000
Supplies and other current assets	(13,000)	(11,000)
Aircraft maintenance deposits	(4,000)	(5,000)
Other long-term assets	(8,000)	(7,000)
Accounts payable	6,000	4,000
Air traffic liability	95,000	25,000
Other liabilities	71,000	(141,000)
Cash provided by (used in) operating activities	30,000	(180,000)
Cash flows from investing activities:
Capital expenditures	(3,000)	(2,000)
Pre-delivery deposits for flight equipment, net of refunds	12,000	(9,000)
Other	(2,000)	0
Cash provided by (used in) investing activities	7,000	(11,000)
Cash flows from financing activities:
Proceeds from issuance of debt	26,000	56,000
Principal repayments on debt	(22,000)	(43,000)
Proceeds from sale-leaseback transactions	13,000	22,000
Minimum tax withholdings on share-based awards	(3,000)	0
Cash provided by financing activities	14,000	35,000
Net increase (decrease) in cash, cash equivalents and restricted cash	51,000	(156,000)
Cash, cash equivalents and restricted cash, beginning of period	378,000	768,000
Cash, cash equivalents and restricted cash, end of period	$ 429,000	$ 612,000

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)
Beginning balance (in shares) at Dec. 31, 2019		199,242,854
Beginning balance at Dec. 31, 2019	$ 542,000	$ 0	$ 52,000	$ 486,000	$ 4,000
Net income (loss)	(64,000)			(64,000)
Unrealized loss from cash flows hedges net of adjustment for dedesignation of fuel hedges, net of tax	(26,000)				(26,000)
Stock-based compensation	2,000		2,000
Ending balance (in shares) at Mar. 31, 2020		199,242,854
Ending balance at Mar. 31, 2020	$ 454,000	$ 0	54,000	422,000	(22,000)
Beginning balance (in shares) at Dec. 31, 2020	199,438,098	199,438,098
Beginning balance at Dec. 31, 2020	$ 310,000	$ 0	60,000	261,000	(11,000)
Net income (loss)	(91,000)			(91,000)
Unrealized loss from cash flows hedges net of adjustment for dedesignation of fuel hedges, net of tax	0
Stock-based compensation	3,000		3,000
Shares issued in connection with vesting of restricted stock units (in shares)		505,438
Shares withheld to cover employee taxes on vested restricted stock units (in shares)		(146,490)
Shares withheld to cover employee taxes on vested restricted stock units	$ (3,000)		(3,000)
Restricted stock unit repurchases (in shares)		(20,368)
Stock option exercise (in shares)	640,121	640,121
Ending balance (in shares) at Mar. 31, 2021	200,416,799	200,416,799
Ending balance at Mar. 31, 2021	$ 219,000	$ 0	$ 60,000	$ 170,000	$ (11,000)

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Statement of Comprehensive Income [Abstract]
Unrealized losses from cash flow hedges net of adjustment for dedesignation of fuel hedges, net of deferred tax benefit	$ 11,000

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The condensed consolidated financial statements have been prepared in accordance with the accounting principles generally accepted in the United States (“GAAP”) and include the accounts of Frontier Group Holdings, Inc. (“FGHI” or the “Company”) and its wholly-owned direct and indirect subsidiaries, including Frontier Airlines Holdings, Inc. (“FAH”) and Frontier Airlines, Inc. (“Frontier”). All wholly-owned subsidiaries are consolidated, with all intercompany transactions and balances being eliminated. Prior to December 3, 2013, FAH was a wholly-owned subsidiary of Republic Airways Holdings, Inc. (“Republic”). On December 3, 2013, FGHI, formerly known as Falcon Acquisition Group, Inc., purchased from Republic all of FAH’s common stock for $52 million in cash and assumed all of its obligations. As a result of the acquisition, all of FAH’s assets and liabilities were remeasured to fair value as of the acquisition date. The Company is headquartered in Denver, Colorado. Frontier is an ultra low-cost, low-fare airline that offers flights throughout the United States and to select international destinations in the Americas, serving approximately 110 airports. The Company is managed as a single business unit that primarily provides air transportation for passengers. Management has concluded there is only one reportable segment. The accompanying condensed consolidated financial statements include the accounts of the Company and reflect all normal recurring adjustments which management believes are necessary to fairly present 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 financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) for Form 10-Q. These unaudited interim condensed consolidated financial statements should be read in conjunction with the audited financial statements of the Company and notes thereto included in the Company's final prospectus, dated March 31, 2021, and filed with the SEC pursuant to Rule 424(b)(4) on April 2, 2021. The interim results reflected in the unaudited condensed consolidated financial statements are not necessarily indicative of the results that may be expected for other interim periods or for the full year. The air transportation business is subject to significant seasonal fluctuations and is volatile and highly affected by economic cycles and trends. In addition, the Company experienced significant impacts from the novel strain of coronavirus (“COVID-19”) pandemic during the three months ended March 31, 2021, as well as during the comparable period in 2020. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities in the financial statements and accompanying notes. Actual results could differ from those estimates. Initial Public Offering On March 31, 2021, the Company’s registration statement on Form S-1 relating to the Company’s initial public offering (“IPO”) was declared effective by the SEC, and the Company’s common stock began trading on the NASDAQ Global Select Market on April 1, 2021 under ticker symbol ULCC. The Company completed its IPO on April 6, 2021 at an offering price of $19.00 per share, pursuant to the Company’s registration statement. The Company issued and sold 15 million shares of common stock and the Company’s selling stockholders sold 15 million shares of common stock in the IPO . The underwriters were granted an over-allotment option to purchase up to 4.5 million additional shares of common stock from the selling shareholders, at the IPO price of $19.00 per share, less the underwriting discount, for 30 days from the date of the prospectus, which was exercised in full in April 2021. T he Company did not receive any of the proceeds from the sale of shares by the Company’s selling stockholders. In April 2021, the Company received net proceeds of $271 million after deducting underwriting discounts and commissions. Because the IPO did not close until April 6, 2021, the transaction is not reflected in the condensed consolidated financial statements provided herein. Total common shares outstanding after the closing of the IPO was 215,416,799. Prior to the IPO and as of March 31, 2021, deferred offering costs, which consist of direct incremental legal, accounting, consulting and other fees relating to the IPO, in the estimated amount of $6 million were capitalized in other current assets on the condensed consolidated balance sheets and were all unpaid. Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes (“ASU 2019-12”). ASU 2019-12 simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740 and also enhances the existing guidance for consistent application of Topic 740. The new guidance is effective for annual periods beginning after December 15, 2020 and interim reporting periods within those reporting periods. The Company adopted the new standard as of January 1, 2021, which did not have a material impact on the Company’s results of operations or financial position as of the adoption date. In August 2020, the FASB issued ASU 2020-06, Accounting for Convertible Instrument and Contracts in an Entity’s Own Equity (“ASU 2020-06”). ASU 2020-06 simplifies the accounting and measurement of convertible instruments and also adds disclosure requirements. Further, ASU 2020-06 simplifies the settlement assessment performed to determine whether a contract in the Company’s own equity qualifies for equity classification. The Company early adopted the standard effective January 1, 2021 using the modified retrospective approach, which did not have a material impact on the Company’s results of operations or financial position as of the adoption date. Given the Company’s IPO in April 2021, and based in part on the provisions of ASU 2020-06, warrants issued in conjunction with the CARES Act that may be settled in the Company’s own equity if publicly traded, are expected to be treated as equity classified awards post IPO.

Impact of COVID-19

Impact of COVID-19	3 Months Ended
	Mar. 31, 2021
Unusual or Infrequent Items, or Both [Abstract]
Impact of COVID-19	Impact of COVID-19 Impact of the COVID-19 Pandemic Beginning in March 2020, the rapid spread of COVID-19, along with government mandated restrictions on travel, required stay-in-place orders, and other social distancing measures, resulted in a drastic decline in near-term air travel demand in the United States, and caused reductions in revenues and income levels as compared to corresponding pre-pandemic periods. The decline in demand for air travel has had a material adverse effect on the Company’s business and results of operations for the period ended March 31, 2021 and the comparable prior year period. Additionally, the Company is unable to predict the future spread of COVID-19 or any new strains of the virus along with resulting measures that may be introduced by governments or other parties and what impact they may have on the demand for air travel. In response to the impacts of the COVID-19 pandemic, beginning in March 2020 and continuing through March 2021, the Company has taken measures to address the significant cash outflows experienced to date, which most notably included aligning capacity to demand, and continues to evaluate options to align costs with expected demand. Beginning in December 2020, the Food and Drug Administration issued emergency use authorizations for various vaccines for COVID-19. As the vaccines continue to be distributed, administered and made available to a broader range of the population, the Company expects confidence in travel to increase, particularly in the domestic leisure market on which the Company’s business is focused. While the Company has experienced a 14% increase in passenger volumes during the quarter ended March 31, 2021 as compared to the fourth quarter of 2020 as well as a meaningful increase in bookings during the first quarter of 2021 compared to the fourth quarter of 2020, the Company continues to closely monitor the COVID-19 pandemic and the need to adjust capacity and deploy other operational and cost-control measures as necessary to preserve short-term liquidity needs and ensure long-term viability of the Company and its strategies. Any anticipated adjustments to capacity and other cost savings initiatives implemented by the Company may vary from actual demand and capacity needs. The Company continues to monitor covenant compliance with various parties, including, but not limited to, its lenders and credit card processors, as any noncompliance could have a material impact on the Company’s financial position, cash flows and results of operations. As of March 31, 2021 and through the date of this report, the Company is in compliance with all of its covenants, except the Company has obtained a waiver of relief for the covenant provisions through the second quarter of 2021 related to one of its credit card processors that represents less than 10% of total revenues, which may require future waivers or an amendment to the existing covenants to reflect any additional COVID-19 pandemic impacts. COVID-19 Relief Funding The Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) became law on March 27, 2020 and includes various provisions to protect the U.S. airline industry, its employees, and many other stakeholders. The CARES Act is a relief package intended to assist many aspects of the American economy, including providing the airline industry with up to $25 billion for a Payroll Support Program (“PSP”) to be used for employee wages, salaries, and benefits and up to $25 billion in loans. On April 30, 2020, the Company reached an agreement with the U.S. Department of the Treasury (the “Treasury”) under which the Company received $211 million of installment funding comprised of a $178 million grant (“PSP Grant”) for payroll support for the period from April 2020 through September 30, 2020, and a $33 million unsecured 10-year, low interest loan (“PSP Promissory Note”). During 2020, the Company received the full $178 million under the PSP Grant, which was recognized net of $1 million in deferred financing costs over the periods it was intended to support payroll, within CARES Act credits in the Company’s condensed consolidated statements of operations. In conjunction with the PSP Promissory Note, the Company issued to the Treasury warrants to acquire up to 522,576 shares of common stock of FGHI at an exercise price of $6.36 per share. On January 15, 2021, as a result of the Consolidated Appropriations Act of 2021, which extended the PSP provisions of the CARES Act, the Company entered into an agreement with the Treasury for a minimum of $140 million of installment funding under a second Payroll Support Program (“PSP2”), comprised of a $128 million grant (“PSP2 Grant”) for the continuation of payroll support through March 31, 2021, and a $12 million unsecured 10-year low interest loan (“PSP2 Promissory Note”), all of which was received during the three months ended March 31, 2021. In conjunction with the PSP2 Promissory Note, the Company issued to the Treasury warrants to acquire up to 103,208 shares of common stock of FGHI at an exercise price of $11.65 per share. As of March 31, 2021, the $12 million PSP2 Promissory Note is presented net of unamortized discounts related to warrants and deferred financing costs totaling $1 million within long-term debt, net on the Company’s condensed consolidated balance sheet. Of the $128 million received under the PSP2 Grant, $125 million was recognized within CARES Act credits in the Company’s condensed consolidated statements of operations, and the remaining $3 million was deferred within other current liabilities on the Company's condensed consolidated balance sheet. Subsequent to March 31, 2021, the Treasury provided the Company with an additional disbursement under the PSP2 Agreement of $21 million on April 29, 2021, comprised of an additional $15 million toward the PSP2 Grant and $6 million toward the PSP2 Promissory Note. In conjunction with this additional funding, the Company issued to the Treasury warrants to purchase up to 54,105 additional shares of common stock of FGHI at an exercise price of $11.65 per share. The American Rescue Plan Act (“ARP”), enacted on March 11, 2021, provided for additional assistance to passenger air carriers that received financial relief under PSP2 ("PSP3"). On April 29, 2021, the Company entered into an agreement with the Treasury for approximately $150 million of installment funding under PSP3 (the “PSP3 Agreement”), comprised of a $135 million grant (“PSP3 Grant”) for the continuation of payroll support through September 30, 2021, and a $15 million unsecured 10-year low interest loan (“PSP3 Promissory Note”). In conjunction with funding from PSP3, the Company agreed to issue to the Treasury warrants to purchase up to 79,961 additional shares of common stock of FGHI at an exercise price of $18.85 per share. The impacts of PSP3 are not reflected within the Company’s March 31, 2021 condensed consolidated financial statements. On September 28, 2020, the Company entered into a loan agreement with the Treasury for a term loan facility of up to $574 million pursuant to the secured loan program established under the CARES Act (“Treasury Loan”). As of March 31, 2021, the Company has borrowed $150 million under the Treasury Loan, which is presented net of unamortized discounts related to warrants and deferred financing costs, within long-term debt, net on the Company’s condensed consolidated balance sheets. Additional funding can be drawn on the loan through May 28, 2021 and includes a maximum of three total draws on the facility. In conjunction with the Treasury Loan, the Company issued to the Treasury warrants to acquire the common stock of FGHI, which have a five-year term and are settled in cash or shares. As of March 31, 2021, the Company had issued 2,358,090 warrants with an exercise price of $6.36 per share in conjunction with the first draw on the loan. In connection with the Company’s participation in the PSP, PSP2, PSP3 and the Treasury Loan, the Company has been and will continue to be subject to certain restrictions and limitations, including, but not limited to: • Restrictions on repurchases of equity securities listed on a national securities exchange or payment of dividends until the later of September 30, 2022 or one year after the Treasury Loan facility is repaid; • Requirements to maintain certain levels of scheduled services through March 31, 2022 (including to destinations where there may currently be significantly reduced or no demand); • A prohibition on involuntary terminations or furloughs of employees (except for health, disability, cause, or certain disciplinary reasons) through September 30, 2021; • A prohibition on reducing the salary, wages or benefits of our employees (other than our executive officers or independent contractors, or as otherwise permitted under the terms of the PSP, PSP2 and PSP3) through September 30, 2021; • Limits on certain executive compensation, including limiting pay increases and severance pay or other benefits upon terminations, until the later of April 1, 2023 or one year after the Treasury Loan facility is repaid; • Limitations on the use of the grant funds exclusively for the continuation of payment of employee wages, salaries and benefits; and • Additional reporting and recordkeeping requirements. As outlined above, as part of the PSP Promissory Note, the PSP2 Promissory Note and the Treasury Loan, and pursuant to the stipulations set forth within the CARES Act, the Company issued to the Treasury warrants to acquire shares of common stock of FGHI, which have a five-year term and are settled in cash or shares. The warrants do not have any voting rights and are freely transferable, with registration rights. The warrants issued in conjunction with the CARES Act financing have been classified as liability based awards within other current liabilities on the condensed consolidated balance sheets and, as of March 31, 2021 and December 31, 2020, the warrant liability was $39 million and $18 million, respectively. Given the liability based classification, at the end of each period the warrant liability is adjusted to its fair market value, calculated utilizing the Black Scholes option pricing model, with the corresponding fair market value adjustment classified as interest expense within the Company’s condensed consolidated statements of operations, which was $20 million for the three months ended March 31, 2021. The initial fair value of these warrants upon issuance is treated as a loan discount, which reduces the carrying value of the loan, and is amortized utilizing the effective interest method as interest expense in the Company’s condensed consolidated statements of operations over the term of the loan. The CARES Act also provided for an employee retention credit (“CARES Employee Retention Credit”), which is a refundable tax credit against certain employment taxes that the Company qualified for beginning on April 1, 2020. In December 2020, the CARES Employee Retention Credit program was extended and enhanced through June 30, 2021. Further, in March 2021, the ARP further extended the availability of the CARES Employee Retention Credit through December 31, 2021. The ARP increased the credit from 50% to 70% of qualified wages, increased the maximum wages per employee from $10,000 for the entire period to $10,000 per quarter, and expanded the gross receipts test for eligible employers from a 50% to an 80% decline in gross receipts as compared to the same calendar quarter in 2019. During the three months ended March 31, 2021, the Company recognized $11 million related to the CARES Employee Retention Credit within CARES Act credits in the Company’s condensed consolidated statements of operations and other current assets on the Company’s condensed consolidated balance sheets. Income Taxes The Company's effective tax rate for the three months ended March 31, 2021 was 19.5%, compared to 37.9% for the three months ended March 31, 2020. The effective tax rate for the three months ended March 31, 2021 deviates from the statutory rate primarily due to non-deductible interest from the mark to market adjustments from the warrants issued to the Treasury as part of the Company’s participation in the PSP, PSP2, and the Treasury Loan, partially offset by excess tax benefits associated with the Company’s stock-based compensation arrangements. The decrease in tax rate as compared to the prior year period is largely driven by the CARES Act benefit that allowed the 2020 net operating loss to be carried back to tax years in which a federal 35% tax rate applied, resulting in a permanent benefit of the 14% rate differential.

Revenue Recognition

Revenue Recognition	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition As of December 31, 2020, the Company’s air traffic liability balance was $135 million. During the three months ended March 31, 2021, 41% of the air traffic liability as of December 31, 2020 has been recognized as passenger revenue. As of March 31, 2021, the Company’s current air traffic liability is $230 million, of which $44 million is related to customer rights to book future travel, which generally expire 12 months after issuance if not redeemed by the passenger. The amounts expected not to be redeemed are recognized over the historical pattern of rights exercised by customers. During the three months ended March 31, 2021 and 2020, the Company recognized $10 million and $9 million of revenue, respectively, within passenger revenue within the condensed consolidated statements of operations, primarily related to expected and actual expiration of customer rights to book future travel. Frequent Flyer Program The Company’s Frontier Miles frequent flyer program provides frequent flyer travel awards to program members based on accumulated mileage credits. Mileage credits are generally accumulated as a result of travel, purchases using the co-branded credit card and purchases from other participating partners. The Company defers revenue for mileage credits earned by passengers under its Frontier Miles program based on the equivalent ticket value (“ETV”) a passenger receives by redeeming mileage credits for a ticket rather than paying cash. Mileage credits are also sold to participating companies, including credit card companies and other third parties. Sales to credit card companies include multiple promised goods and services, which the Company evaluates to determine whether they represent performance obligations. The Company determined these arrangements have three separate performance obligations: (i) mileage credits to be awarded, (ii) licensing of brand and access to member lists and (iii) advertising and marketing efforts. Total arrangement consideration is allocated to each performance obligation on the basis of the deliverables relative standalone selling price. For mileage credits, the Company considers a number of entity-specific factors when developing the best estimate of the standalone selling price, including the number of mileage credits needed to redeem an award, average fare of comparable segments, breakage and restrictions. For licensing of brand and access to member lists, the Company considers both market-specific factors and entity-specific factors, including general profit margins realized in the marketplace/industry, brand power, market royalty rates and size of customer base. For the advertising and marketing performance obligation, the Company considers market-specific factors and entity-specific factors, including the Company’s internal costs of providing services, volume of marketing efforts and overall advertising plan. Consideration allocated based on the relative standalone selling price to both the brand licensing and access to member lists and advertising and marketing elements is recognized as other revenue in the Company’s condensed consolidated statements of operations over time as mileage credits are delivered. The consideration allocated to the transportation portion of these mileage credit sales is deferred and recognized as a component of passenger revenue in the Company’s condensed consolidated statements of operations at the time of travel for mileage credits redeemed. Mileage credits the Company estimates are not likely to be redeemed are subject to breakage and are recognized as a portion of passenger revenue in proportion to the pattern of rights exercised by customers. Management uses statistical models to estimate breakage based on historical redemption patterns. A change in assumptions as to the period over which mileage credits are expected to be redeemed, the actual redemption activity for mileage credits or the estimated fair value of mileage credits expected to be redeemed could have an impact on revenues in the year in which the change occurs and in future years. Redemptions are allocated between sold and flown mileage credits based on historical patterns. Operating revenues are comprised of passenger revenues, which includes fare and non-fare passenger revenues, and other revenues. Disaggregated operating revenues are as follows (in millions) Three Months Ended March 31, 2021 2020 Passenger revenues: Fare $ 100 $ 219 Non-fare passenger revenues: Baggage 67 109 Service fees 62 141 Seat selection 24 43 Other 9 16 Total non-fare passenger revenue 162 309 Total passenger revenues 262 528 Other revenues 9 16 Total operating revenues $ 271 $ 544 The Company is managed as a single business unit that provides air transportation for passengers. Operating revenues by principal geographic region, as defined by the U.S. Department of Transportation (the “DOT”), are as follows (in millions): Three Months Ended March 31, 2021 2020 Domestic $ 259 $ 500 Latin America 12 44 Total operating revenues $ 271 $ 544

Other Current Assets

Other Current Assets	3 Months Ended
	Mar. 31, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Current Assets	Other Current Assets Other current assets consist of the following (in millions): March 31, 2021 December 31, 2020 Prepaid expenses $ 17 $ 24 Income tax receivable 161 161 Passenger and other taxes receivable 20 26 Other 25 15 Total other current assets $ 223 $ 226

Financial Derivative Instrument

Financial Derivative Instruments and Risk Management	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Derivative Instruments and Risk Management	Financial Derivative Instruments and Risk Management The Company is exposed to variability in jet fuel prices. Aircraft fuel generally represents the Company’s largest operating expense. Increases in jet fuel prices may adversely impact its financial performance, operating cash flow and financial position. As part of its risk management program, the Company enters into derivative contracts in order to limit exposure to the fluctuations in jet fuel price s. The types of instruments the Company utilized in its 2020 hedging program were call options and collar structures, which include both a purchased call option and sold put option. A lthough the use of collar structures can reduce the overall cost of hedging, these instruments carry more risk than purchased call options alone in that these instruments may result in a net liability for the Company upon settlement. Additionally, the Company is exposed to interest rate risk through aircraft lease contracts for the time period between agreement of terms and commencement of the lease, where portions of the rental payments are adjusted and become fixed based on the seven The Company formally designates and accounts for derivative instruments that meet established accounting criteria under ASC 815, Derivatives and Hedging , as cash flow hedges. For derivative instruments that are designated and qualify as cash flow hedges, the gain or loss on the derivative instruments is recorded in accumulated other comprehensive income/loss (“AOCI/L”), a component of stockholders’ equity on the condensed consolidated balance sheets. The Company recognizes the associated gains or losses deferred in AOCI/L as well as the amounts that are paid or received in connection with the purchase or sale of fuel-related financial derivative instruments (i.e., premium costs of option contracts) as a component of aircraft fuel expense in the period that the jet fuel subject to hedging is consumed for its fuel derivative instruments. For interest rate derivatives, the Company recognizes the associated gains or losses deferred in AOCI/L as well as amounts that are paid or received in connection with the purchase or sale of interest rate derivative instruments (i.e., premium costs of swaption contracts) as a component of aircraft rent expense over the period of the related aircraft lease. The Company does not enter into derivative instruments for speculative purposes. In March 2020, the Company determined that it was no longer probable that estimated future fuel consumption for gallons subjected to fuel hedges would occur, primarily related to second quarter 2020 settled trades as the Company reduced scheduled flights as a result of the decline in customer demand from the COVID-19 pandemic, and, therefore, the Company was required to de-designate certain fuel hedges associated with estimated future consumption declines. Fuel hedges with identified estimated future fuel consumption that were probable to still occur remained within AOCI/L. As a result of the de-designation, in March 2020 the Company recognized a $56 million loss within aircraft fuel in the condensed consolidated statements of operations. As of March 31, 2021, the Company had no fuel cash flow hedges outstanding, and the Company has hedged the interest rate exposure on $327 million of total aircraft rent payments for eight aircraft to be delivered by the end of 2021. The Company is exposed to credit losses in the event of nonperformance by counterparties to its derivative instruments but does not expect any of its counterparties will fail to meet their obligations. The amount of such credit exposure is generally the fair value of the Company’s outstanding contracts in a receivable position. To manage credit risks, the Company selects counterparties based on credit assessments, limits its overall exposure to any single counterparty and monitors the market position with each counterparty. Based on the fair value of the Company’s fuel derivative instruments, its counterparties may require it to post collateral when the price of the underlying commodity decreases, and the Company may require its counterparties to provide collateral when the price of the underlying commodity increases. The amount of collateral posted, if any, is periodically adjusted based on the fair value of the hedge contracts. The Company’s policy is to offset the liabilities represented by these contracts with any cash collateral paid to the counterparties. The assets and liabilities associated with the Company’s fuel and interest rate derivative instruments are presented on a gross basis and include upfront premiums paid. These are recorded as a component of other current assets and other current liabilities on the Company’s condensed consolidated balance sheets and as of March 31, 2021 and December 31, 2020, were less than $1 million. The following table summarizes the effect of fuel and interest rate derivative instruments reflected in aircraft fuel and rent expense, respectively, in the condensed consolidated statements of operations (in millions): Three Months Ended March 31, 2021 2020 Derivatives designated as cash flow hedges Losses on fuel derivative contracts $ — $ (13) Derivatives not designated as cash flow hedges Losses on fuel derivative contracts $ — $ (56) The following table presents the net of tax impact of the overall effectiveness of derivative instruments designated as cash flow hedging instruments in the condensed consolidated statements of comprehensive income (loss) (in millions): Three Months Ended March 31, 2021 2020 Derivatives designated as cash flow hedges Fuel derivative contract losses – net of tax impact $ — $ (26) Fuel derivative losses reclassified to earnings due to de-designation – net of tax impact — 9 Interest rate derivative contract losses – net of tax impact — (9) Total $ — $ (26)

Other Current Liabilities

Other Current Liabilities	3 Months Ended
	Mar. 31, 2021
Other Liabilities Disclosure [Abstract]
Other Current Liabilities	Other Current Liabilities Other current liabilities consist of the following (in millions): March 31, 2021 December 31, 2020 Salaries, wages and benefits $ 85 $ 97 Current portion of phantom equity units (Note 9) 26 — Station obligations 44 33 Leased aircraft return costs 14 20 Aircraft maintenance 36 22 Passenger and other taxes and fees payable 63 41 Fuel liabilities 16 6 Warrant liability 39 18 Other current liabilities 46 30 Total other current liabilities $ 369 $ 267

Debt

Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Debt	Debt The Company’s debt obligations are as follows (in millions): March 31, 2021 December 31, 2020 Secured debt: Pre-delivery credit facility (1) $ 133 $ 141 Floating rate building note (2) 18 18 Treasury Loan (3) 150 150 Unsecured debt: Affinity card advance purchase of mileage credits (4) 15 15 PSP Promissory Notes (5) 45 33 Total debt 361 357 Less current maturities of long-term debt, net (110) (101) Less long-term debt acquisition costs and other discounts (9) (9) Long-term debt, net $ 242 $ 247 __________________ (1) The Company, through an affiliate, entered into the pre-delivery payment (“PDP”) facility with Citibank, N.A. in December 2014 (“PDP Financing Facility”). The PDP Financing Facility is collateralized by the Company’s purchase agreement for Airbus A320neo and A321neo aircraft through 2023 (see Note 10). On December 22, 2020, the PDP Financing Facility was amended and restated to reduce the commitment of Citibank, N.A., as initial lender, to $150 million, remove the ability to draw further unsecured borrowings and to provide collateral for the borrowings not secured by aircraft outstanding as of that date. During May 2021, the Company amended the facility to increase the total available capacity to $200 million and expanded the number of financial institution participants as lenders. Interest is paid every 90 days based on a three-month LIBOR, plus a margin for each individual tranche. The PDP Financing Facility consists of separate loans for each PDP aircraft. Each separate loan matures upon the earlier of (i) delivery of that aircraft to the Company by Airbus, (ii) the date one month following the last day of the scheduled delivery month of such aircraft and (iii) if there is a delay in delivery of aircraft, depending on the cause of the delivery delay, up to six months following the last day of the scheduled delivery month of such aircraft. The PDP Financing Facility will be repaid periodically according to the preceding sentence with the last scheduled delivery of aircraft contemplated in the PDP Financing Facility expected to be in the fourth quarter of 2023. (2) Represents a note with National Bank of Arizona related to the Company’s headquarters building. Under the terms of the agreement, the Company will repay outstanding principal balance in quarterly payments beginning in January 2022 until the maturity date in December 2023. On the maturity date, one final balloon payment will be made to cover all unpaid principal, accrued unpaid interest and other amounts due. The interest rate of one-month LIBOR plus a margin is payable monthly. (3) On September 28, 2020, the Company entered into the Treasury Loan with the Treasury for a term loan facility of up to $574 million. The Treasury Loan has a five-year term and includes an annual interest rate based on adjusted LIBOR plus 2.5%. Additional funding can be drawn on the loan through May 28, 2021 and includes a maximum of three total draws on the facility, and it can be prepaid at par at any time without incurring a penalty. The Treasury Loan is collateralized by the Company’s co-branded credit card arrangement. As part of any funding under the loan program, the Company is required to comply with the relevant provisions of the CARES Act, which will apply until one year after the loan is repaid in full. In conjunction with the Treasury Loan, the Company issued to the Treasury warrants to acquire the common stock of FGHI, which have a five-year term and are settled in cash or shares upon notice from the Treasury. Such warrants are included in other current liabilities on the Company’s condensed consolidated balance sheets. As of March 31, 2021, the Company had issued 2,358,090 warrants to the Treasury in conjunction with the Treasury Loan. (4) The Company entered into an agreement with Barclays in 2003 to provide for joint marketing, grant certain benefits to co-branded credit card holders (“Cardholders”), and allow Barclays to market using the Company’s customer database. Cardholders earn mileage credits under the Frontier Miles program and the Company sells mileage credits at agreed-upon rates to Barclays and earns fees from Barclays for the acquisition, retention and use of the co-branded credit card by consumers. In addition, Barclays will pre-purchase miles if the Company meets certain conditions precedent. On September 15, 2020 the Company entered into a new agreement with Barclays to amend and extend the agreement to 2029. The pre-purchased miles facility amount is to be reset on January 15 of each calendar year through and including January 15, 2028 based on the aggregate amount of fees payable by Barclays to the Company on a calendar year basis, up to an aggregate maximum facility amount of $200 million. The facility amount cannot be extended above $15 million until full extinguishment of the Treasury Loan. The Company pays interest on a monthly basis, which is based on a one-month LIBOR plus a margin. Beginning March 31, 2028, the facility will be repaid in 12 equal monthly installments. (5) On April 30, 2020, the Company executed the PSP Promissory Note with the Treasury as part of the original payroll support program in which the Company received a $33 million unsecured 10-year, low interest loan. Subsequently, as part of the PSP2 Agreement, in March 2021 the Company received an additional $12 million of proceeds with the same terms as the original PSP Promissory Note. The PSP Promissory Notes include an annual interest rate of 1.00% for the first five years and the Secured Overnight Financing Rate ("SOFR") plus 2.00% in the final five years. The loans can be prepaid at par any time without incurring a penalty. In conjunction with the PSP Promissory Notes, the Company issued to the Treasury warrants to acquire up to 625,784 shares of common stock of FGHI, which have a five-year term and are settled in cash or shares. Such warrants are included in other current liabilities on the Company’s condensed consolidated balance sheets. Cash payments for interest related to debt was $1 million and $2 million for the three months ended March 31, 2021 and 2020, respectively. The Company has issued standby letters of credit and surety bonds to various airport authorities and vendors that are collateralized by restricted cash and as of March 31, 2021 and December 31, 2020, the Company did not have any outstanding letters of credit that were drawn upon. As of March 31, 2021, future maturities of debt are payable as follows (in millions): March 31, 2021 Remainder of 2021 $ 79 2022 52 2023 20 2024 — 2025 150 Thereafter 60 Total debt principal payments $ 361

Operating Leases

Operating Leases	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Operating Leases	Operating LeasesThe Company leases property and equipment under operating leases. For leases with initial terms greater than 12 months, the related asset and obligation is recorded at the present value of lease payments over the term. Some leases include rental escalation clauses, renewal options, termination options, and/or other items that cause variability that are factored into the determination of lease payments when appropriate. The Company does not separate lease and non-lease components of contracts, except for certain flight training equipment, for which consideration is allocated between lease and non-lease components. Aircraft As of March 31, 2021, the Company leased 107 aircraft, all of which are under operating leases with remaining terms ranging from three months to 12 years. In addition, as of March 31, 2021, the Company leased 17 spare engines, which are all under operating leases. As of March 31, 2021, the remaining terms for engines included within right-of-use asset and lease liability range from five months to 12 years. During the three months ended March 31, 2021 and 2020, th e Company executed sale-leaseback transactions with third-party lessors for three new Airbus A320 family aircraft. Additionally, the Company completed a sale-leaseback transaction for one engine during the three months ended March 31, 2021 and did not complete any sale-leaseback transactions for engines during the three months ended March 31, 2020. All of the leases from the sale-leaseback transactions are accounted for as operating leases. During the three months ended March 31, 2021 a nd 2020, the Company acquired, through new operating leases, aircraft and engines totaling $120 million and $96 million, respectively, which are included in operating lease right-of-use assets on the condensed consolidated balance sheets and also recognized net sale-leaseback gains of $15 million and $17 million, respectively, from those sale-leaseback transactions which are included as a component of other operating expenses within the condensed consolidated statements of operations. In March 2020, the Company entered into two amendments with one lessor that were treated as one combined contract. One amendment extended the remaining lease terms on two aircraft from three In May 2021, the Company entered into an early termination and buyout agreement with one of its lessors for six aircraft that were previously owned by the Company, which stipulates that four A319 aircraft originally slated to be returned in December 2021 will be returned during the second and third quarters of 2021. The early returns of these aircraft will retire the remaining A319 aircraft in the Company’s fleet. As a result of this early termination and buyout arrangement the Company recorded a $6 million charge included as a component of rent expense within the condensed consolidated statements of operations for the three months ended March 31, 2021 related to the change in expected lease return obligations of which $4 million was related to the A319 aircraft returning in the second quarter. Aircraft Rent Expense and Maintenance Obligations Aircraft rent expense was $138 million and $103 million during the three months ended March 31, 2021 and 2020, respectively. Aircraft rent expense includes supplemental rent, which is made up of maintenance reserves paid or to be paid that are not probable of being reimbursed or are probable lease return condition obligations. Supplemental rent expense for maintenance-related reserves that were deemed non-recoverable during the years ended March 31, 2021 and 2020 totaled $1 million and less than $1 million, respectively. The portion of supplemental rent expense related to probable lease return condition obligations was $14 million and $4 million for March 31, 2021 and 2020, respectively. Additionally, c ertain of the Company’s aircraft and spare engine lease agreements require the Company to pay maintenance reserves to aircraft lessors to be held as collateral in advance of the Company’s required performance of major maintenance activities. As of March 31, 2021 and December 31, 2020, the Company had aircraft maintenance deposits that are expected to be recoverable of $92 million and $82 million, respectively, on its condensed consolidated balance sheets of which $6 million and less than $1 million, respectively, are included in accounts receivable, net as the eligible maintenance has been performed. The remaining $86 million and $82 million are included within aircraft maintenance deposits on the condensed consolidated balance sheets as of March 31, 2021 and December 31, 2020, respectively. A majority of these maintenance reserve payments are calculated based on a utilization measure, such as flight hours or cycles. Maintenance reserves collateralize the lessor for maintenance time run off the aircraft until the completion of the maintenance of the aircraft. As of March 31, 2021, fixed maintenance reserve payments for aircraft and spare engines, including estimated amounts for contractual price escalations, were expected to be approximately $3 million per year for the remainder of 2021 through 2025 and $11 million thereafter before consideration of reimbursements. Airport Facilities The Company’s facility leases are primarily for space at approximately 110 airports that are served and are primarily located in the United States. These leases are classified as operating leases and reflect the use of airport terminals, ticket counters, office space, cargo warehouses and maintenance facilities. Generally, this space is leased from government agencies that control the use of the airport. The majority of these leases are short-term in nature and renew on an evergreen basis. For these leases, the contractual term is used as the lease term. As of March 31, 2021, the remaining lease terms vary from one month to eight years. At the majority of the U.S. airports, the lease rates depend on airport operating costs or use of the facilities and are reset at least annually. Because of the variable nature of the rates, these leases are not recorded on the condensed consolidated balance sheets as a right-of-use asset and lease liability. Other Ground Property and Equipment The Company leases certain other assets such as flight training equipment, building space, and various other equipment. Certain of the Company’s leases for other assets are deemed to contain fixed rental payments and, as such, are classified as operating leases and are recorded on the condensed consolidated balance sheets as a right-of-use asset and liability. The remaining lease terms range from one month to eight years as of March 31, 2021. Lessor Concessions In response to the COVID-19 pandemic, beginning in 2020, the Company was granted payment deferrals on leases included in the Company’s right-of-use assets for certain aircraft and engines from lessors along with airport facilities and other vendors that are not included in the Company’s right-of-use assets. As these deferred payments are made, the Company will recognize the deferred payments in aircraft rent or station operations, as applicable, in the condensed consolidated statements of operations. These deferrals decreased operating cash flows and unfavorably impacted the Company’s results of operations by $11 million for the three months ended March 31, 2021, including a $19 million unfavorable impact to aircraft rent and an $8 million favorable impact to station operations. As of March 31, 2021, the Company has $22 million of rent payment deferrals that have yet to be recognized, including $12 million and $10 million related to aircraft rent expense and station operations, respectively, which will be recognized throughout the rest of 2021 and future years as such amounts are paid. Lease Costs The table below presents certain information related to lease costs for operating leases during the three months ended March 31, 2021 and 2020 (in millions): Three Months Ended March 31, 2021 2020 Operating lease cost (1) $ 107 $ 98 Variable lease cost (1) 65 45 Total lease costs $ 172 $ 143 ______________ (1) Expenses are included within aircraft rent, station operations, maintenance materials and repairs and other operating in the Company’s condensed consolidated statements of operations. During the three months ended March 31, 2021 a nd 2020, the Company paid cash of $108 million and $99 million, respectively, for amounts included in the measurement of lease liabilities.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation During the three months ended March 31, 2021 and 2020, the Company recognized $3 million and $2 million, respectively, in stock-based compensation expense, which is included as a component of salaries, wages and benefits within the condensed consolidated statements of operations. Stock Options and Restricted Awards In April 2014, FGHI approved the 2014 Equity Incentive Plan (the “2014 Plan”). Under the terms of the 2014 Plan, 38 million shares of FGHI common stock are reserved for issuance. Concurrently with the Company’s initial public offering on April 1, 2021, the Company approved the 2021 Incentive Award Plan (the “2021 Plan”), which reserved 7 million shares of FGHI common stock, as well as the 11 million issued awards from the 2014 Plan that are still outstanding plus any subsequently forfeited awards or awards that lapse unexercised after April 1, 2021, to be available for future issuances of stock-based compensation awards to be granted to members of the Board of Directors and certain employees and consultants. Additionally, shares available for issuance under the 2021 Plan will be subject to an annual increase on the first day of each fiscal year beginning in 2022 and ending in 2031, equal to the lesser of (A) one percent (1%) of the shares of stock outstanding on the last day of the immediately preceding fiscal year and (B) such smaller number of shares of stock as determined by the Company’s Board of Directors; provided, however, that no more than 30 million shares of stock may be issued upon the exercise of incentive stock options. There were no options granted during the three months ended March 31, 2020 and 2021. In connection with the Company initial public offering, 640,121 of vested stock options were exercised with a weig hted average stock price of $0.64 per share during the three months ended March 31, 2021. The weighted average exercise price of outstanding options as of March 31, 2021 was $2.02 per share. During the three months ended March 31, 2021, 695,742 restricted stock units were issued with a weighted average grant date fair value of $13.84 per share and an aggregate fair value of $10 million. Additionally, during the three months ended March 31, 2021, the Company withheld 146,490 restricted stock units with a weighted average grant date fair value of $10.98 per share to cover employee taxes upon award vesting.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Flight Equipment Commitments As of March 31, 2021, the Company’s firm aircraft and engine orders consisted of the following: A320neo A321neo Total Engines Year Ending Remainder of 2021 10 — 10 2 2022 9 5 14 4 2023 — 19 19 2 2024 — 19 19 2 2025 17 8 25 3 Thereafter 50 16 66 9 Total 86 67 153 22 During December 2017, the Company entered into an amendment to the previously existing master purchase agreement with Airbus. Pursuant to the amendment, the Company had a commitment to purchase an incremental 100 A320neo and 34 A321neo aircraft (“incremental aircraft”) which were scheduled to be delivered through 2026. During July 2019, the Company entered into an amendment to the previously existing master purchase agreement that included the conversion of 15 A320neo aircraft to A321neo aircraft and, in December 2020, the Company entered into an amendment to convert an additional 18 A320neo aircraft to A321neo aircraft, each of which also updated the timing of original scheduled delivery dates as reflected in the table above. A dditionally, the Company entered into an amendment that allows it the option to convert 18 A320neo aircraft to A321XLR aircraft and therefore, the conversion is not reflected in the table above. The amended agreements provide for varying purchase incentives, which have been allocated proportionally and are accounted for as an offsetting reduction to the cost of the backlog aircraft and incremental aircraft. As a result, cash paid for backlog aircraft will be more than the associated capitalized cost of the aircraft and results in the recognition of a deferred purchase incentive within other assets on the condensed consolidated balance sheets, which will ultimately be offset by the lower cash payments in connection with the purchase of the incremental aircraft. On April 13, 2020, the Company entered into an agreement with Pratt & Whitney for a purchase commitment to supply all engines and the related maintenance services for the Company’s incremental order book. These deliveries will begin in 2022 and are expected to occur through 2027. In addition, Pratt & Whitney will supply a certain number of spare engines from 2022 through 2029. These commitments are reflected within the table above and in the future commitments below. As of March 31, 2021, purchase commitments for these aircraft and engines, including estimated amounts for contractual price escalations and PDPs, were approximately $522 million in the remainder of 2021, $765 million in 2022, $1,095 million in 2023, $1,144 million in 2024, $1,422 million in 2025 and $3,906 million thereafter. Litigation and Other Contingencies On March 12, 2021, the DOT advised the Company that it was in receipt of information indicating that the Company had failed to comply with certain DOT consumer protection requirements relating to consumer refund and credit practices and requested that the Company provide certain information to the DOT. The DOT request for information is focused on the Company’s refund practices on Frontier initiated flight cancellations and/or significant changes in flights as a result of the COVID-19 pandemic. The Company is fully cooperating with the DOT request. The Company is subject to commercial litigation claims and to administrative and regulatory proceedings and reviews that may be asserted or maintained from time to time. The Company regularly evaluates the status of such matters to assess whether a loss is probable and reasonably estimable in determining whether an accrual is appropriate. Furthermore, in determining whether disclosure is appropriate, the Company evaluates each matter to assess if there is at least a reasonable possibility that a loss or additional losses may have been incurred and whether an estimate of possible loss or range of loss can be made. The Company believes the ultimate outcome of such lawsuits, proceedings, and reviews will not, individually or in the aggregate, have a material adverse effect on its condensed consolidated financial position, liquidity, or results of operations and that the Company’s current accruals cover matters where loss is deemed probable and can be reasonably estimated. The ultimate outcome of legal actions is unpredictable and can be subject to significant uncertainties, and it is difficult to determine whether any loss is probable or even possible. Additionally, it is also difficult to estimate the amount of loss and there may be matters for which a loss is probable or reasonably possible but not currently estimable. Thus, actual losses may be in excess of any recorded liability or the range of reasonably possible loss. Employees The Company has seven union-represented employee groups that together represent approximately 87% of all employees at March 31, 2021. The table below sets forth the Company’s employee groups and status of the collective bargaining agreements as of March 31, 2021: Percentage of Workforce Employee Group Representative Amendable Date March 31, 2021 Pilots Air Line Pilots Association (ALPA) January 2024 32% Flight Attendants Association of Flight Attendants (AFA-CWA) May 2024 51% Aircraft Technicians International Brotherhood of Teamsters (IBT) March 2024 2% Aircraft Appearance IBT October 2023 <1% Material Specialists IBT March 2022 <1% Dispatchers Transport Workers Union (TWU) December 2021 <1% Maintenance Control IBT October 2023 <1% The Company is self-insured for health care claims, subject to a stop-loss policy, for eligible participating employees and qualified dependent medical and dental claims, subject to deductibles and limitations. The Company’s liabilities for claims incurred but not reported are determined based on an estimate of the ultimate aggregate liability for claims incurred. The estimate is calculated from actual claim rates and adjusted periodically as necessary. The Company has accrued $4 million for health care claims estimated to be incurred but not yet paid as of March 31, 2021 and December 31, 2020, which is included as a component of other current liabilities on the condensed consolidated balance sheets. General Indemnifications The Company has various leases with respect to real property as well as various agreements among airlines relating to fuel consortia or fuel farms at airports. Under some of these contracts, the Company is party to joint and several liability regarding environmental damages. Under others, where the Company is a member of an LLC or other entity that contracts directly with the airport operator, liabilities are borne through the fuel consortia structure. The Company’s aircraft, services, equipment lease and sale and financing agreements typically contain provisions requiring us, as the lessee, obligor or recipient of services, to indemnify the other parties to those agreements, including certain of those parties’ related persons, against virtually any liabilities that might arise from the use or operation of the aircraft or such other equipment. The Company believes that its insurance would cover most of its exposure to liabilities and related indemnities associated with the commercial real estate leases and aircraft, services, equipment lease and sale and financing agreements described above. Certain of the Company’s aircraft and other financing transactions include provisions that require payments to preserve an expected economic return to the lenders if that economic return is diminished due to certain changes in law or regulations. In certain of these financing transactions and other agreements, the Company also bears the risk of certain changes in tax laws that would subject payments to non-U.S. entities to withholding taxes.

Net Earnings (Loss) per Share

Net Earnings (Loss) per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Net Earnings (Loss) per Share	Net Earnings (Loss) per ShareBasic and diluted earnings (loss) per share are computed pursuant to the two-class method. Under the two-class method, the Company attributes net income to common stock and other participating rights (including those with vested share-based awards). Basic net earnings (loss) per share is calculated by taking net income, less earnings allocated to participating rights, divided by the basic weighted average common stock outstanding. Diluted net earnings (loss) per share is calculated using the more dilutive of the treasury-stock method and the two-class method. The following table sets forth the computation of net earnings (loss) per share on a basic and diluted basis pursuant to the two-class method for the periods indicated (in millions, except for share and per share data): Three months ended March 31, 2021 2020 Basic: Net income (loss) $ (91) $ (64) Less: net income attributable to participating rights — — Net income (loss) attributable to common stockholders $ (91) $ (64) Weighted average common shares outstanding, basic 199,482,701 199,187,260 Net earnings (loss) per share, basic $ (0.46) $ (0.32) Diluted: Net income (loss) $ (91) $ (64) Less: net income attributable to participating rights — — Net income (loss) attributable to common stockholders $ (91) $ (64) Weighted-average common shares outstanding, basic 199,482,701 199,187,260 Effect of dilutive potential common shares — — Weighted average common shares outstanding, diluted 199,482,701 199,187,260 Net earnings (loss) per share, diluted $ (0.46) $ (0.32)

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Under ASC 820, Fair Value Measurements and Disclosures , disclosures relating to how fair value is determined for assets and liabilities are required, and a hierarchy for which these assets and liabilities must be grouped is established, based on significant levels of inputs, as follows: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The Company utilizes several valuation techniques in order to assess the fair value of its financial assets and liabilities. Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents as of March 31, 2021 and December 31, 2020 were comprised of liquid money market funds, time deposits and cash, and are categorized as Level 1 instruments. The Company maintains cash with various high-quality financial institutions. Within restricted cash, the Company also maintains certificates of deposit that secure certain letters of credit issued for workers’ compensation claim reserves and certain airport authorities. Cash, cash equivalents and restricted cash are carried at cost, which management believes approximates fair value. Warrants The estimated fair value of the warrants issued in conjunction with the loans from the CARES Act, described in Note 2 , was determined to be Level 3 measurement. The primary inputs to the warrant valuation are driven by FGHI’s share price as well as assumptions about the expected share price volatility and estimated term the warrants will remain outstanding. These inputs are largely impacted by internal forecasts, discount rates and other internal assumptions as well as assumptions used by the participating underwriters to establish the initial offering price related to the Company’s IPO, which were unobservable as of March 31, 2021. For the three months ended March 31, 2021, the Company’s warrant liability increased by $21 million, which was driven by mark to market adjustments of $20 million and $1 million of additional warrants issued in conjunction with PSP2 funding obtained during the three months ended March 31, 2021. Debt The estimated fair value of the Company’s debt agreements has been determined to be Level 3 measurement, as certain inputs used to determine the fair value of these agreements are unobservable. The Company utilizes a discounted cash flow method to estimate the fair value of the Level 3 long-term debt. The carrying amounts and estimated fair values of the Company’s debt are as follows (in millions): March 31, 2021 December 31, 2020 Carrying Estimated Fair Value Carrying Value Estimated Fair Value Secured debt: Pre-delivery credit facility $ 133 $ 131 $ 141 $ 139 Floating rate building note 18 18 18 18 Treasury Loan 150 153 150 148 Unsecured debt: Affinity card advance purchase of mileage credits 15 14 15 11 PSP Promissory Note 45 35 33 25 Total debt $ 361 $ 351 $ 357 $ 341 The tables below present disclosures about the fair value of assets and liabilities measured at fair value on a recurring basis in the Company’s financial statements (in millions): Fair Value Measurements as of March 31, 2021 Total Level 1 Level 2 Level 3 Cash and cash equivalents $ 429 $ 429 $ — $ — Warrants $ 39 $ — $ — $ 39 Fair Value Measurements as of December 31, 2020 Total Level 1 Level 2 Level 3 Cash and cash equivalents $ 378 $ 378 $ — $ — Warrants $ 18 $ — $ — $ 18

Related Parties

Related Parties	3 Months Ended
	Mar. 31, 2021
Related Party Transactions [Abstract]
Related Parties	Related Parties Management Services The Company pays a quarterly fee to Indigo Partners for management services, plus expense reimbursements and the annual fees of each member of the Company’s board of directors that is affiliated with Indigo Partners. Indigo Partners manages an investment fund that is the controlling stockholder in FGHI. The Company paid Indigo Partners $1 million and less than $1 million of management fees, expense reimbursements, and director compensation for the three months ended March 31, 2021 and 2020, respectively. Codeshare Arrangement The Company entered into a codeshare agreement with Controladora Vuela Compañía de Aviación, S.A.B. de C.V. (an airline based in Mexico doing business as Volaris) during 2018, under which sales began in July 2018. Two of the Company’s directors are members of the board of directors of Volaris. Indigo Partners holds approximately 18% of the total outstanding Common Stock shares of Volaris.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of PresentationThe condensed consolidated financial statements have been prepared in accordance with the accounting principles generally accepted in the United States (“GAAP”)
Consolidation, Policy	Basis of PresentationThe condensed consolidated financial statements have been prepared in accordance with the accounting principles generally accepted in the United States (“GAAP”) and include the accounts of Frontier Group Holdings, Inc. (“FGHI” or the “Company”) and its wholly-owned direct and indirect subsidiaries, including Frontier Airlines Holdings, Inc. (“FAH”) and Frontier Airlines, Inc. (“Frontier”). All wholly-owned subsidiaries are consolidated, with all intercompany transactions and balances being eliminated. Prior to December 3, 2013, FAH was a wholly-owned subsidiary of Republic Airways Holdings, Inc. (“Republic”). On December 3, 2013, FGHI, formerly known as Falcon Acquisition Group, Inc., purchased from Republic all of FAH’s common stock for $52 million in cash and assumed all of its obligations. As a result of the acquisition, all of FAH’s assets and liabilities were remeasured to fair value as of the acquisition date.
Use of Estimates	Use of EstimatesThe preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities in the financial statements and accompanying notes. Actual results could differ from those estimates.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes (“ASU 2019-12”). ASU 2019-12 simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740 and also enhances the existing guidance for consistent application of Topic 740. The new guidance is effective for annual periods beginning after December 15, 2020 and interim reporting periods within those reporting periods. The Company adopted the new standard as of January 1, 2021, which did not have a material impact on the Company’s results of operations or financial position as of the adoption date. In August 2020, the FASB issued ASU 2020-06, Accounting for Convertible Instrument and Contracts in an Entity’s Own Equity (“ASU 2020-06”). ASU 2020-06 simplifies the accounting and measurement of convertible instruments and also adds disclosure requirements. Further, ASU 2020-06 simplifies the settlement assessment performed to determine whether a contract in the Company’s own equity qualifies for equity classification. The Company early adopted the standard effective January 1, 2021 using the modified retrospective approach, which did not have a material impact on the Company’s results of operations or financial position as of the adoption date. Given the Company’s IPO in April 2021, and based in part on the provisions of ASU 2020-06, warrants issued in conjunction with the CARES Act that may be settled in the Company’s own equity if publicly traded, are expected to be treated as equity classified awards post IPO.
Frequent Flyer Program	Frequent Flyer Program The Company’s Frontier Miles frequent flyer program provides frequent flyer travel awards to program members based on accumulated mileage credits. Mileage credits are generally accumulated as a result of travel, purchases using the co-branded credit card and purchases from other participating partners. The Company defers revenue for mileage credits earned by passengers under its Frontier Miles program based on the equivalent ticket value (“ETV”) a passenger receives by redeeming mileage credits for a ticket rather than paying cash.
Operating Leases	The Company leases property and equipment under operating leases. For leases with initial terms greater than 12 months, the related asset and obligation is recorded at the present value of lease payments over the term. Some leases include rental escalation clauses, renewal options, termination options, and/or other items that cause variability that are factored into the determination of lease payments when appropriate. The Company does not separate lease and non-lease components of contracts, except for certain flight training equipment, for which consideration is allocated between lease and non-lease components.
Fair Value Measurement	Under ASC 820, Fair Value Measurements and Disclosures , disclosures relating to how fair value is determined for assets and liabilities are required, and a hierarchy for which these assets and liabilities must be grouped is established, based on significant levels of inputs, as follows: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The Company utilizes several valuation techniques in order to assess the fair value of its financial assets and liabilities. Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents as of March 31, 2021 and December 31, 2020 were comprised of liquid money market funds, time deposits and cash, and are categorized as Level 1 instruments. The Company maintains cash with various high-quality financial institutions. Within restricted cash, the Company also maintains certificates of deposit that secure certain letters of credit issued for workers’ compensation claim reserves and certain airport authorities. Cash, cash equivalents and restricted cash are carried at cost, which management believes approximates fair value. Warrants The estimated fair value of the warrants issued in conjunction with the loans from the CARES Act, described in Note 2 , was determined to be Level 3 measurement. The primary inputs to the warrant valuation are driven by FGHI’s share price as well as assumptions about the expected share price volatility and estimated term the warrants will remain outstanding. These inputs are largely impacted by internal forecasts, discount rates and other internal assumptions as well as assumptions used by the participating underwriters to establish the initial offering price related to the Company’s IPO, which were unobservable as of March 31, 2021. For the three months ended March 31, 2021, the Company’s warrant liability increased by $21 million, which was driven by mark to market adjustments of $20 million and $1 million of additional warrants issued in conjunction with PSP2 funding obtained during the three months ended March 31, 2021. Debt

Revenue Recognition (Tables)

Revenue Recognition (Tables)	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	Disaggregated operating revenues are as follows (in millions) Three Months Ended March 31, 2021 2020 Passenger revenues: Fare $ 100 $ 219 Non-fare passenger revenues: Baggage 67 109 Service fees 62 141 Seat selection 24 43 Other 9 16 Total non-fare passenger revenue 162 309 Total passenger revenues 262 528 Other revenues 9 16 Total operating revenues $ 271 $ 544
Revenue by Geographic Region	Operating revenues by principal geographic region, as defined by the U.S. Department of Transportation (the “DOT”), are as follows (in millions): Three Months Ended March 31, 2021 2020 Domestic $ 259 $ 500 Latin America 12 44 Total operating revenues $ 271 $ 544

Other Current Assets (Tables)

Other Current Assets (Tables)	3 Months Ended
	Mar. 31, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Other Current Assets	Other current assets consist of the following (in millions): March 31, 2021 December 31, 2020 Prepaid expenses $ 17 $ 24 Income tax receivable 161 161 Passenger and other taxes receivable 20 26 Other 25 15 Total other current assets $ 223 $ 226

Financial Derivative Instrume_2

Financial Derivative Instruments and Risk Management (Tables)	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Effect of Fuel and Interest Rate Derivative Instruments Reflected in Aircraft Fuel and Rent Expense	The following table summarizes the effect of fuel and interest rate derivative instruments reflected in aircraft fuel and rent expense, respectively, in the condensed consolidated statements of operations (in millions): Three Months Ended March 31, 2021 2020 Derivatives designated as cash flow hedges Losses on fuel derivative contracts $ — $ (13) Derivatives not designated as cash flow hedges Losses on fuel derivative contracts $ — $ (56)
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss)	The following table presents the net of tax impact of the overall effectiveness of derivative instruments designated as cash flow hedging instruments in the condensed consolidated statements of comprehensive income (loss) (in millions): Three Months Ended March 31, 2021 2020 Derivatives designated as cash flow hedges Fuel derivative contract losses – net of tax impact $ — $ (26) Fuel derivative losses reclassified to earnings due to de-designation – net of tax impact — 9 Interest rate derivative contract losses – net of tax impact — (9) Total $ — $ (26)

Other Current Liabilities (Tabl

Other Current Liabilities (Tables)	3 Months Ended
	Mar. 31, 2021
Other Liabilities Disclosure [Abstract]
Schedule of Other Current Liabilities	Other current liabilities consist of the following (in millions): March 31, 2021 December 31, 2020 Salaries, wages and benefits $ 85 $ 97 Current portion of phantom equity units (Note 9) 26 — Station obligations 44 33 Leased aircraft return costs 14 20 Aircraft maintenance 36 22 Passenger and other taxes and fees payable 63 41 Fuel liabilities 16 6 Warrant liability 39 18 Other current liabilities 46 30 Total other current liabilities $ 369 $ 267

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Schedule of Debt Obligations	The Company’s debt obligations are as follows (in millions): March 31, 2021 December 31, 2020 Secured debt: Pre-delivery credit facility (1) $ 133 $ 141 Floating rate building note (2) 18 18 Treasury Loan (3) 150 150 Unsecured debt: Affinity card advance purchase of mileage credits (4) 15 15 PSP Promissory Notes (5) 45 33 Total debt 361 357 Less current maturities of long-term debt, net (110) (101) Less long-term debt acquisition costs and other discounts (9) (9) Long-term debt, net $ 242 $ 247 __________________ (1) The Company, through an affiliate, entered into the pre-delivery payment (“PDP”) facility with Citibank, N.A. in December 2014 (“PDP Financing Facility”). The PDP Financing Facility is collateralized by the Company’s purchase agreement for Airbus A320neo and A321neo aircraft through 2023 (see Note 10). On December 22, 2020, the PDP Financing Facility was amended and restated to reduce the commitment of Citibank, N.A., as initial lender, to $150 million, remove the ability to draw further unsecured borrowings and to provide collateral for the borrowings not secured by aircraft outstanding as of that date. During May 2021, the Company amended the facility to increase the total available capacity to $200 million and expanded the number of financial institution participants as lenders. Interest is paid every 90 days based on a three-month LIBOR, plus a margin for each individual tranche. The PDP Financing Facility consists of separate loans for each PDP aircraft. Each separate loan matures upon the earlier of (i) delivery of that aircraft to the Company by Airbus, (ii) the date one month following the last day of the scheduled delivery month of such aircraft and (iii) if there is a delay in delivery of aircraft, depending on the cause of the delivery delay, up to six months following the last day of the scheduled delivery month of such aircraft. The PDP Financing Facility will be repaid periodically according to the preceding sentence with the last scheduled delivery of aircraft contemplated in the PDP Financing Facility expected to be in the fourth quarter of 2023. (2) Represents a note with National Bank of Arizona related to the Company’s headquarters building. Under the terms of the agreement, the Company will repay outstanding principal balance in quarterly payments beginning in January 2022 until the maturity date in December 2023. On the maturity date, one final balloon payment will be made to cover all unpaid principal, accrued unpaid interest and other amounts due. The interest rate of one-month LIBOR plus a margin is payable monthly. (3) On September 28, 2020, the Company entered into the Treasury Loan with the Treasury for a term loan facility of up to $574 million. The Treasury Loan has a five-year term and includes an annual interest rate based on adjusted LIBOR plus 2.5%. Additional funding can be drawn on the loan through May 28, 2021 and includes a maximum of three total draws on the facility, and it can be prepaid at par at any time without incurring a penalty. The Treasury Loan is collateralized by the Company’s co-branded credit card arrangement. As part of any funding under the loan program, the Company is required to comply with the relevant provisions of the CARES Act, which will apply until one year after the loan is repaid in full. In conjunction with the Treasury Loan, the Company issued to the Treasury warrants to acquire the common stock of FGHI, which have a five-year term and are settled in cash or shares upon notice from the Treasury. Such warrants are included in other current liabilities on the Company’s condensed consolidated balance sheets. As of March 31, 2021, the Company had issued 2,358,090 warrants to the Treasury in conjunction with the Treasury Loan. (4) The Company entered into an agreement with Barclays in 2003 to provide for joint marketing, grant certain benefits to co-branded credit card holders (“Cardholders”), and allow Barclays to market using the Company’s customer database. Cardholders earn mileage credits under the Frontier Miles program and the Company sells mileage credits at agreed-upon rates to Barclays and earns fees from Barclays for the acquisition, retention and use of the co-branded credit card by consumers. In addition, Barclays will pre-purchase miles if the Company meets certain conditions precedent. On September 15, 2020 the Company entered into a new agreement with Barclays to amend and extend the agreement to 2029. The pre-purchased miles facility amount is to be reset on January 15 of each calendar year through and including January 15, 2028 based on the aggregate amount of fees payable by Barclays to the Company on a calendar year basis, up to an aggregate maximum facility amount of $200 million. The facility amount cannot be extended above $15 million until full extinguishment of the Treasury Loan. The Company pays interest on a monthly basis, which is based on a one-month LIBOR plus a margin. Beginning March 31, 2028, the facility will be repaid in 12 equal monthly installments.
Schedule of Maturities of Long-term Debt	As of March 31, 2021, future maturities of debt are payable as follows (in millions): March 31, 2021 Remainder of 2021 $ 79 2022 52 2023 20 2024 — 2025 150 Thereafter 60 Total debt principal payments $ 361

Operating Leases (Tables)

Operating Leases (Tables)	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Schedule of Lease Costs	The table below presents certain information related to lease costs for operating leases during the three months ended March 31, 2021 and 2020 (in millions): Three Months Ended March 31, 2021 2020 Operating lease cost (1) $ 107 $ 98 Variable lease cost (1) 65 45 Total lease costs $ 172 $ 143 ______________

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Long-term Purchase Commitment	As of March 31, 2021, the Company’s firm aircraft and engine orders consisted of the following: A320neo A321neo Total Engines Year Ending Remainder of 2021 10 — 10 2 2022 9 5 14 4 2023 — 19 19 2 2024 — 19 19 2 2025 17 8 25 3 Thereafter 50 16 66 9 Total 86 67 153 22
Multiemployer Plan	The table below sets forth the Company’s employee groups and status of the collective bargaining agreements as of March 31, 2021: Percentage of Workforce Employee Group Representative Amendable Date March 31, 2021 Pilots Air Line Pilots Association (ALPA) January 2024 32% Flight Attendants Association of Flight Attendants (AFA-CWA) May 2024 51% Aircraft Technicians International Brotherhood of Teamsters (IBT) March 2024 2% Aircraft Appearance IBT October 2023 <1% Material Specialists IBT March 2022 <1% Dispatchers Transport Workers Union (TWU) December 2021 <1% Maintenance Control IBT October 2023 <1%

Net Earnings (Loss) per Share (

Net Earnings (Loss) per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule Of Earnings Per Share Basic And Diluted	The following table sets forth the computation of net earnings (loss) per share on a basic and diluted basis pursuant to the two-class method for the periods indicated (in millions, except for share and per share data): Three months ended March 31, 2021 2020 Basic: Net income (loss) $ (91) $ (64) Less: net income attributable to participating rights — — Net income (loss) attributable to common stockholders $ (91) $ (64) Weighted average common shares outstanding, basic 199,482,701 199,187,260 Net earnings (loss) per share, basic $ (0.46) $ (0.32) Diluted: Net income (loss) $ (91) $ (64) Less: net income attributable to participating rights — — Net income (loss) attributable to common stockholders $ (91) $ (64) Weighted-average common shares outstanding, basic 199,482,701 199,187,260 Effect of dilutive potential common shares — — Weighted average common shares outstanding, diluted 199,482,701 199,187,260 Net earnings (loss) per share, diluted $ (0.46) $ (0.32)

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments	The carrying amounts and estimated fair values of the Company’s debt are as follows (in millions): March 31, 2021 December 31, 2020 Carrying Estimated Fair Value Carrying Value Estimated Fair Value Secured debt: Pre-delivery credit facility $ 133 $ 131 $ 141 $ 139 Floating rate building note 18 18 18 18 Treasury Loan 150 153 150 148 Unsecured debt: Affinity card advance purchase of mileage credits 15 14 15 11 PSP Promissory Note 45 35 33 25 Total debt $ 361 $ 351 $ 357 $ 341
Schedule of Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis	The tables below present disclosures about the fair value of assets and liabilities measured at fair value on a recurring basis in the Company’s financial statements (in millions): Fair Value Measurements as of March 31, 2021 Total Level 1 Level 2 Level 3 Cash and cash equivalents $ 429 $ 429 $ — $ — Warrants $ 39 $ — $ — $ 39 Fair Value Measurements as of December 31, 2020 Total Level 1 Level 2 Level 3 Cash and cash equivalents $ 378 $ 378 $ — $ — Warrants $ 18 $ — $ — $ 18

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Basis of Presentation (Details) $ in Millions	Dec. 03, 2013USD ($)	Mar. 31, 2021reportableSegmentairport
Number of airports served | airport		110
Number of reportable segments | reportableSegment		1
Frontier Airlines Holdings, Inc.
Acquisition of outstanding Republic stock | $	$ 52

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Initial Public Offering (Details) - USD ($) $ / shares in Units, $ in Millions	Apr. 06, 2021	Mar. 31, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Common shares outstanding after initial public offering (in shares)		200,416,799	199,438,098
Deferred offering costs		$ 6
Subsequent Event
Class of Stock [Line Items]
Common shares outstanding after initial public offering (in shares)	215,416,799
IPO | Subsequent Event
Class of Stock [Line Items]
Common stock issued and sold (in shares)	15,000,000
Common stock issued (in dollars per share)	$ 19
Proceeds from initial public offering, net of underwriting discounts and offering expenses	$ 271
Public Stock Offering - Shares From Existing Shareholders | Subsequent Event
Class of Stock [Line Items]
Common stock issued and sold (in shares)	15,000,000
Over-Allotment Option | Subsequent Event
Class of Stock [Line Items]
Common stock issued and sold (in shares)	4,500,000

Impact of COVID-19 - Impact of

Impact of COVID-19 - Impact of the COVID-19 Pandemic (Details)	3 Months Ended
	Mar. 31, 2021
Unusual or Infrequent Items, or Both [Abstract]
Increase in passenger volume from fourth quarter of 2020	14.00%

Impact of COVID-19 - COVID-19 R

Impact of COVID-19 - COVID-19 Relief Funding (Details) $ / shares in Units, $ in Thousands

Apr. 29, 2021USD ($)$ / sharesshares

Jan. 15, 2021

Sep. 28, 2020USD ($)draw

Apr. 30, 2020

Apr. 29, 2021USD ($)$ / sharesshares

Mar. 31, 2021USD ($)$ / sharesshares

Mar. 31, 2021USD ($)$ / sharesshares

Mar. 31, 2020USD ($)

Sep. 30, 2021USD ($)

Sep. 30, 2020USD ($)$ / sharesshares

Sep. 30, 2021USD ($)

Sep. 30, 2020USD ($)$ / sharesshares

Dec. 31, 2020USD ($)

Unusual Risk or Uncertainty [Line Items]

Mark to market adjustment on warrant

$ 20,000

$ 0

Long-term debt, gross

$ 361,000

361,000

$ 357,000

Employee retention credit

11,000

Less long-term debt acquisition costs and other discounts

9,000

9,000

9,000

Warrant liability

$ 39,000

$ 39,000

$ 18,000

Warrants outstanding, term

5 years

5 years

Total debt

$ 361,000

$ 361,000

Effective tax rate

19.50%

37.90%

PSP1 Promissory Note

Unusual Risk or Uncertainty [Line Items]

Deferred financing costs

$ 1,000

The Coronavirus Aid, Relief, and Economic Security Act | PSP1 Promissory Note

Unusual Risk or Uncertainty [Line Items]

Funding received

$ 211,000

Proceeds from Payroll Support Program grant

$ 178,000

The Coronavirus Aid, Relief, and Economic Security Act | Consolidated Appropriations Act of 2021 - PSP 2

Unusual Risk or Uncertainty [Line Items]

Funding received

$ 140,000

Proceeds from Payroll Support Program grant

$ 128,000

The Coronavirus Aid, Relief, and Economic Security Act | Other Current Assets | Consolidated Appropriations Act of 2021 - PSP 2

Unusual Risk or Uncertainty [Line Items]

Proceeds from Payroll Support Program grant

3,000

The Coronavirus Aid, Relief, and Economic Security Act | CARES Act, Credits | Consolidated Appropriations Act of 2021 - PSP 2

Unusual Risk or Uncertainty [Line Items]

Proceeds from Payroll Support Program grant

$ 125,000

Subsequent Event | The Coronavirus Aid, Relief, and Economic Security Act | Consolidated Appropriations Act of 2021 - PSP 2

Unusual Risk or Uncertainty [Line Items]

Funding received

$ 21,000

Proceeds from Payroll Support Program grant

$ 15,000

Subsequent Event | The American Rescue Plan Act | PSP3 Promissory Note Warrants

Unusual Risk or Uncertainty [Line Items]

Funding received

$ 150,000

Proceeds from Payroll Support Program grant

$ 135,000

PSP Promissory Note Warrants

Unusual Risk or Uncertainty [Line Items]

Exercise price of warrants (in dollars per share) | $ / shares

$ 6.36

$ 6.36

PSP Promissory Note Warrants | PSP1 Promissory Note

Unusual Risk or Uncertainty [Line Items]

Warrants to acquire common stock (in shares) | shares

522,576

522,576

Exercise price of warrants (in dollars per share) | $ / shares

$ 6.36

$ 6.36

PSP2 Promissory Note Warrants | Consolidated Appropriations Act of 2021 - PSP 2

Unusual Risk or Uncertainty [Line Items]

Warrants to acquire common stock (in shares) | shares

103,208

103,208

Exercise price of warrants (in dollars per share) | $ / shares

$ 11.65

$ 11.65

PSP2 Promissory Note Warrants | Subsequent Event | Consolidated Appropriations Act of 2021 - PSP 2

Unusual Risk or Uncertainty [Line Items]

Warrants to acquire common stock (in shares) | shares

54,105

54,105

Exercise price of warrants (in dollars per share) | $ / shares

$ 11.65

$ 11.65

PSP3 Promissory Note Warrants | Subsequent Event | PSP3 Promissory Note Warrants

Unusual Risk or Uncertainty [Line Items]

Warrants to acquire common stock (in shares) | shares

79,961

79,961

Exercise price of warrants (in dollars per share) | $ / shares

$ 18,850,000

$ 18,850,000

CARES Act Credit Agreement, Warrants

Unusual Risk or Uncertainty [Line Items]

Warrants to acquire common stock (in shares) | shares

2,358,090

2,358,090

Warrants outstanding, term

5 years

5 years

5 years

Unsecured Debt | Consolidated Appropriations Act of 2021 - PSP 2

Unusual Risk or Uncertainty [Line Items]

Unsecured low interest loan amount

$ 12,000

Less long-term debt acquisition costs and other discounts

1,000

$ 1,000

Unsecured Debt | PSP1 Promissory Note

Unusual Risk or Uncertainty [Line Items]

Unsecured low interest loan amount

$ 33,000

Term of grant

10 years

Unsecured Debt | Consolidated Appropriations Act of 2021 - PSP 2

Unusual Risk or Uncertainty [Line Items]

Unsecured low interest loan amount

12,000

Term of grant

10 years

Unsecured Debt | Consolidated Appropriations Act of 2021 - PSP 2 | Subsequent Event

Unusual Risk or Uncertainty [Line Items]

Unsecured low interest loan amount

$ 6,000

Unsecured Debt | PSP3 Promissory Note | Subsequent Event

Unusual Risk or Uncertainty [Line Items]

Unsecured low interest loan amount

$ 15,000

Term of grant

10 years

Line of Credit | CARES Credit Agreement

Unusual Risk or Uncertainty [Line Items]

Term of grant

5 years

Term loan amount

$ 574,000

Long-term debt, gross

$ 150,000

$ 150,000

Number of draws available | draw

3

Revenue Recognition - Additiona

Revenue Recognition - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Capitalized Contract Cost [Line Items]
Air traffic liability	$ 230,000		$ 135,000
Customer rights to book future travel	44,000
Passenger revenue recongnized	$ 10,000	$ 9,000
Passenger
Capitalized Contract Cost [Line Items]
Air traffic liability recognized as passenger revenue	41.00%

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregated Operating Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 271,000	$ 544,000
Total passenger revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	262,000	528,000
Fare
Disaggregation of Revenue [Line Items]
Total operating revenues	100,000	219,000
Total non-fare passenger revenue
Disaggregation of Revenue [Line Items]
Total operating revenues	162,000	309,000
Baggage
Disaggregation of Revenue [Line Items]
Total operating revenues	67,000	109,000
Service fees
Disaggregation of Revenue [Line Items]
Total operating revenues	62,000	141,000
Seat selection
Disaggregation of Revenue [Line Items]
Total operating revenues	24,000	43,000
Other
Disaggregation of Revenue [Line Items]
Total operating revenues	9,000	16,000
Other
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 9,000	$ 16,000

Revenue Recognition - Operating

Revenue Recognition - Operating Revenues by Principal Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 271,000	$ 544,000
Domestic
Disaggregation of Revenue [Line Items]
Total operating revenues	259,000	500,000
Latin America
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 12,000	$ 44,000

Other Current Assets (Details)

Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses	$ 17,000	$ 24,000
Income tax receivable	161,000	161,000
Passenger and other taxes receivable	20,000	26,000
Other	25,000	15,000
Total other current assets	$ 223,000	$ 226,000

Financial Derivative Instrume_3

Financial Derivative Instruments and Risk Management - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021USD ($)aircraft	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Derivative [Line Items]
Losses from de-designated derivative positions	$ 0	$ (56,000,000)
Derivative, other current assets	1,000,000		$ 1,000,000
Derivative, other current liabilities	$ 1,000,000		$ 1,000,000
Minimum
Derivative [Line Items]
Interest rate risk, time period between agreements	7 years
Maximum
Derivative [Line Items]
Interest rate risk, time period between agreements	9 years
Interest Rate Swap
Derivative [Line Items]
Cost of swap	$ 0	4,000,000
Interest rate exposure on aircraft rent payments	$ 327,000,000
Number of aircraft payments hedged | aircraft	8
Unrealized losses from cash flow hedges net of adjustment for dedesignation of fuel hedges, net of deferred tax benefit	$ 11,000,000
Fuel Derivative Contracts
Derivative [Line Items]
Losses from de-designated derivative positions	0	$ (56,000,000)
Notional amount	$ 0

Financial Derivative Instrume_4

Financial Derivative Instruments and Risk Management - Effect of Fuel and Interest Rate Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative [Line Items]
Losses on fuel derivative contracts	$ 0	$ (56,000)
Fuel Derivative Contracts
Derivative [Line Items]
Losses on fuel derivative contracts	0	(13,000)
Losses on fuel derivative contracts	$ 0	$ (56,000)

Financial Derivative Instrume_5

Financial Derivative Instruments and Risk Management - Net of Tax Impact of the Overall Effectiveness of Derivative Instruments Designated as Cash Flow Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative [Line Items]
Derivative contract losses, net of tax impact	$ 0	$ (26,000)
Fuel Derivative Contracts
Derivative [Line Items]
Fuel derivative contract losses – net of tax impact	0	(26,000)
Fuel derivative losses reclassified to earnings due to de-designation – net of tax impact	0	9,000
Interest Rate Swap
Derivative [Line Items]
Fuel derivative contract losses – net of tax impact	$ 0	$ (9,000)

Other Current Liabilities (Deta

Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Other Liabilities Disclosure [Abstract]
Salaries, wages and benefits	$ 85,000	$ 97,000
Current portion of phantom equity units	26,000	0
Station obligations	44,000	33,000
Leased aircraft return costs	14,000	20,000
Aircraft maintenance	36,000	22,000
Passenger and other taxes and fees payable	63,000	41,000
Fuel liabilities	16,000	6,000
Other current liabilities	46,000	30,000
Total other current liabilities	$ 369,000	$ 267,000

Debt - Schedule of Debt Obligat

Debt - Schedule of Debt Obligations (Details) $ in Thousands	Apr. 29, 2021USD ($)	Jan. 15, 2021	Sep. 28, 2020USD ($)draw	Apr. 30, 2020	Mar. 31, 2021USD ($)shares	Mar. 31, 2021USD ($)shares	Sep. 30, 2020USD ($)	May 31, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 22, 2020USD ($)	Sep. 15, 2020USD ($)
Debt Instrument [Line Items]
Long-term debt, gross					$ 361,000	$ 361,000			$ 357,000
Less current maturities of long-term debt, net					(110,000)	(110,000)			(101,000)
Less long-term debt acquisition costs and other discounts					(9,000)	(9,000)			(9,000)
Long-term debt, net					$ 242,000	$ 242,000			247,000
Warrants outstanding, term					5 years	5 years
CARES Act Credit Agreement, Warrants
Debt Instrument [Line Items]
Warrants to acquire common stock (in shares) | shares					2,358,090	2,358,090
Warrants outstanding, term			5 years		5 years	5 years
Payroll Support Program Promissory Note, CARES Act, Warrant
Debt Instrument [Line Items]
Warrants to acquire common stock (in shares) | shares					625,784	625,784
Warrants outstanding, term				5 years
Secured Debt | Pre-delivery credit facility
Debt Instrument [Line Items]
Long-term debt, gross					$ 133,000	$ 133,000			141,000
Amount of unsecured borrowings available										$ 150,000
Secured Debt | Pre-delivery credit facility | Subsequent Event
Debt Instrument [Line Items]
Amount of unsecured borrowings available								$ 200,000
Secured Debt | Floating rate building note
Debt Instrument [Line Items]
Long-term debt, gross					18,000	18,000			18,000
Secured Debt | CARES Credit Agreement
Debt Instrument [Line Items]
Long-term debt, gross					150,000	150,000			150,000
Unsecured Debt | Affinity card advance purchase of mileage credits
Debt Instrument [Line Items]
Long-term debt, gross					15,000	15,000			15,000
Amount of unsecured borrowings available											$ 200,000
Unsecured Debt | PSP Promissory Note
Debt Instrument [Line Items]
Long-term debt, gross					$ 45,000	$ 45,000			$ 33,000
Interest rate					1.00%	1.00%
Interest rate period						5 years
Unsecured Debt | PSP Promissory Note | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Debt Instrument [Line Items]
Debt instrument, variable interest rate						2.00%
Unsecured Debt | PSP1 Promissory Note
Debt Instrument [Line Items]
Loan term				10 years
Unsecured low interest loan amount							$ 33,000
Unsecured Debt | Consolidated Appropriations Act of 2021 - PSP 2
Debt Instrument [Line Items]
Loan term		10 years
Unsecured low interest loan amount					$ 12,000
Unsecured Debt | Consolidated Appropriations Act of 2021 - PSP 2 | Subsequent Event
Debt Instrument [Line Items]
Unsecured low interest loan amount	$ 6,000
Line of Credit | CARES Credit Agreement
Debt Instrument [Line Items]
Long-term debt, gross					$ 150,000	$ 150,000
Amount of unsecured borrowings available			$ 574,000
Loan term			5 years
Number of draws available | draw			3
Period of compliance			1 year
Line of Credit | CARES Credit Agreement | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, variable interest rate			2.50%

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Debt Disclosure [Abstract]
Interest paid	$ 1,000	$ 2,000

Debt - Schedule of Maturity (De

Debt - Schedule of Maturity (Details) $ in Thousands	Mar. 31, 2021USD ($)
Debt Disclosure [Abstract]
Remainder of 2021	$ 79,000
2022	52,000
2023	20,000
2024	0
2025	150,000
Thereafter	60,000
Total debt principal payments	$ 361,000

Operating Leases - Aircraft (De

Operating Leases - Aircraft (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)aircraftaircraftEngine	Mar. 31, 2020USD ($)aircraftaircraftEngineamendment	May 12, 2021aircraft	Feb. 28, 2020
Lessee, Lease, Description [Line Items]
Gains recognized on sale-leaseback transactions	$ 15,000	$ 17,000
Number of amendments | amendment		2
Number of aircraft renewed | aircraft		2
Length of contract		5 years		3 years
Return of previously unrecoverable maintenance expense		$ 17,000
Aircraft rent	$ 138,000	$ 103,000
Subsequent Event
Lessee, Lease, Description [Line Items]
Number of aircraft terminated | aircraft			6
Aircraft
Lessee, Lease, Description [Line Items]
Number of leases | aircraft	107
Aircraft | Minimum
Lessee, Lease, Description [Line Items]
Remaining lease terms	3 months
Aircraft | Maximum
Lessee, Lease, Description [Line Items]
Remaining lease terms	12 years
Aircraft Engine
Lessee, Lease, Description [Line Items]
Number of leases | aircraftEngine	17
Aircraft Engine | Aircraft Sale Leaseback
Lessee, Lease, Description [Line Items]
Number of sale-leaseback transactions | aircraftEngine	1	0
Aircraft Engine | Minimum
Lessee, Lease, Description [Line Items]
Remaining lease terms	5 months
Aircraft Engine | Maximum
Lessee, Lease, Description [Line Items]
Remaining lease terms	12 years
Aircraft and Aircraft Engines
Lessee, Lease, Description [Line Items]
Acquired aircraft and engines through operating leases	$ 120,000	$ 96,000
Gains recognized on sale-leaseback transactions	$ 15,000	$ 17,000
A-320 | Aircraft | Aircraft Sale Leaseback
Lessee, Lease, Description [Line Items]
Number of sale-leaseback transactions | aircraft	3	3
A-319
Lessee, Lease, Description [Line Items]
Charge related to early termination of lease	$ 6,000
A-319 | Subsequent Event
Lessee, Lease, Description [Line Items]
Number of aircraft terminated | aircraft			4
A-319, To Be Returned In Q2
Lessee, Lease, Description [Line Items]
Charge related to early termination of lease	$ (4,000)

Operating Leases - Aircraft Ren

Operating Leases - Aircraft Rent Expense and Maintenance Obligations (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Leases [Abstract]
Aircraft rent expense	$ 138	$ 103
Supplemental rent expense for maintenance-related reserves deemed non-recoverable	1	1
Supplemental rent expense related to probable lease return condition obligations	14	$ 4
Aircraft maintenance deposits expected to be recoverable	92		$ 82
Aircraft maintenance deposits expected to be recoverable, eligible maintenance performed	6		1
Aircraft maintenance deposits	86		$ 82
Maintenance reserve payments, due remainder of fiscal year	3
Maintenance reserve payments, due in year one	3
Maintenance reserve payments, due in year two	3
Maintenance reserve payments, due in year three	3
Maintenance reserve payments, due in year four	3
Maintenance reserve payments, due after year four	$ 11

Operating Leases - Airport Faci

Operating Leases - Airport Facilities (Details)	3 Months Ended
	Mar. 31, 2021airport
Lessee, Lease, Description [Line Items]
Number of airports served	110
Minimum | Airport Facility
Lessee, Lease, Description [Line Items]
Remaining lease terms	1 month
Maximum | Airport Facility
Lessee, Lease, Description [Line Items]
Remaining lease terms	8 years

Operating Leases - Other Ground

Operating Leases - Other Ground Property and Equipment (Details) - Other Ground Property And Equipment	Mar. 31, 2021
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease terms	1 month
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease terms	8 years

Operating Leases - Lessor Conce

Operating Leases - Lessor Concessions (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Lessee, Lease, Description [Line Items]
Deferrals related to leases	$ (11,000)
Deferrals related to leases, yet to be recognized	22,000
Aircraft Rental
Lessee, Lease, Description [Line Items]
Deferrals related to leases	(19,000)
Deferrals related to leases, yet to be recognized	12,000
Station Operations
Lessee, Lease, Description [Line Items]
Deferrals related to leases	8,000
Deferrals related to leases, yet to be recognized	$ 10,000

Operating Leases - Lease Cost (

Operating Leases - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Operating lease cost	$ 107,000	$ 98,000
Variable lease cost	65,000	45,000
Total lease costs	$ 172,000	$ 143,000

Operating Leases - Additional I

Operating Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Cash paid for amounts included in measurement of lease liabilities	$ 108	$ 99

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock-based compensation expense	$ 3	$ 2

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Options and Restricted Awards (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 01, 2021	Mar. 31, 2021	Mar. 31, 2020	Apr. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)		0	0
Stock option exercise (in shares)		640,121
Weighted average stock price (in dollars per share)		$ 0.64
Weighted average exercise price of outstanding options (in dollars per share)		$ 2.02
2014 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)				38,000,000
2021 Equity Incentive Plan | Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)	7,000,000
Common stock issued (in shares)	11,000,000
Maximum number of shares of stock that may be issued upon the exercise of incentive stock options	1.00%
Maximum number of shares of stock that may be issued upon the exercise of incentive stock options (in shares)	30,000,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units issued (in shares)		695,742
Weighted average grant date fair value (in dollars per share)		$ 13.84
Aggregate fair value		$ 10,000
Shares withheld to cover employee taxes on vested restricted stock units (in shares)		146,490
Weighted average grant date fair value (in dollars per share)		$ 10.98

Stock-Based Compensation - Liab

Stock-Based Compensation - Liability-Classified Awards (Details) - USD ($) $ in Thousands	1 Months Ended
	Mar. 31, 2020	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Current portion of phantom equity units		$ 26,000	$ 0
Phantom Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Associated liability, previous				$ 137,000
Associated liability	$ 111,000
Current portion of phantom equity units		$ 26,000
Noncurrent portion of phantom equity units			$ 26,000

Commitments and Contingencies -

Commitments and Contingencies - Aircraft and Engine Orders (Details)	1 Months Ended	3 Months Ended
	Dec. 31, 2017aircraft	Mar. 31, 2021aircraftEngineaircraft
Air Transportation Equipment
Long-term Purchase Commitment [Line Items]
Remainder of 2021		10
2022		14
2023		19
2024		19
2025		25
Thereafter		66
Total		153
Aircraft Engine
Long-term Purchase Commitment [Line Items]
Remainder of 2021 | aircraftEngine		2
2022 | aircraftEngine		4
2023 | aircraftEngine		2
2024 | aircraftEngine		2
2025 | aircraftEngine		3
Thereafter | aircraftEngine		9
Total | aircraftEngine		22
A-320-Neo | Air Transportation Equipment
Long-term Purchase Commitment [Line Items]
Remainder of 2021		10
2022		9
2023		0
2024		0
2025		17
Thereafter		50
Total	100	86
A321neo | Air Transportation Equipment
Long-term Purchase Commitment [Line Items]
Remainder of 2021		0
2022		5
2023		19
2024		19
2025		8
Thereafter		16
Total	34	67

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Dec. 31, 2017aircraft	Mar. 31, 2021USD ($)aircraftaircraftEngineemployee_group	Dec. 31, 2020USD ($)aircraft	Jul. 31, 2019aircraft
Long-term Purchase Commitment [Line Items]
Purchase commitments for aircraft and engines, remainder of 2021		$ 522,000
Purchase commitments for aircraft and engines, 2022		765,000
Purchase commitments for aircraft and engines, 2023		1,095,000
Purchase commitments for aircraft and engines, 2024		1,144,000
Purchase commitments for aircraft and engines, 2025		1,422,000
Purchase commitments for aircraft and engines, thereafter		$ 3,906,000
Number of union-represented employee groups | employee_group		7
Amount of employees represented by unions		87.00%
Accrued liabilities for health care claims		$ 4,000	$ 4,000
Aircraft Engine
Long-term Purchase Commitment [Line Items]
Number of aircraft agreed to purchase | aircraftEngine		22
Air Transportation Equipment
Long-term Purchase Commitment [Line Items]
Number of aircraft agreed to purchase | aircraft		153
Air Transportation Equipment | A-320-Neo
Long-term Purchase Commitment [Line Items]
Number of aircraft agreed to purchase | aircraft	100	86
Number of aircraft eligible for conversion | aircraft			18	15
Air Transportation Equipment | A321neo
Long-term Purchase Commitment [Line Items]
Number of aircraft agreed to purchase | aircraft	34	67
Number of aircraft eligible for conversion | aircraft			18

Commitments and Contingencies_3

Commitments and Contingencies - Collective Bargaining Agreements (Details)	3 Months Ended
	Mar. 31, 2021
Multiemployer Plan [Line Items]
Amount of employees represented by unions	87.00%
Pilots
Multiemployer Plan [Line Items]
Amount of employees represented by unions	32.00%
Flight Attendants
Multiemployer Plan [Line Items]
Amount of employees represented by unions	51.00%
Aircraft Technicians
Multiemployer Plan [Line Items]
Amount of employees represented by unions	2.00%
Aircraft Appearance
Multiemployer Plan [Line Items]
Amount of employees represented by unions	1.00%
Material Specialists
Multiemployer Plan [Line Items]
Amount of employees represented by unions	1.00%
Dispatchers
Multiemployer Plan [Line Items]
Amount of employees represented by unions	1.00%
Maintenance Control
Multiemployer Plan [Line Items]
Amount of employees represented by unions	1.00%

Net Earnings (Loss) per Share_2

Net Earnings (Loss) per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Basic:
Net income (loss)	$ (91,000)	$ (64,000)
Less: net income attributable to participating rights	0	0
Net income (loss) attributable to common stockholders	$ (91,000)	$ (64,000)
Weighted average common shares outstanding, basic (in shares)	199,482,701	199,187,260
Net earnings (loss) per share, basic (in dollars per share)	$ (0.46)	$ (0.32)
Diluted:
Less: net income attributable to participating rights	$ 0	$ 0
Net income (loss) attributable to common stockholders	$ (91,000)	$ (64,000)
Effect of dilutive potential common shares	0	0
Weighted average common shares outstanding, diluted (in shares)	199,482,701	199,187,260
Net earnings (loss) per share, diluted (in dollars per share)	$ (0.46)	$ (0.32)

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mark to market adjustment on warrant	$ 20,000	$ 0
Less long-term debt acquisition costs and other discounts	9,000		$ 9,000
PSP Promissory Note
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Increase to warrant liability	$ 21,000

Fair Value Measurements - Carry

Fair Value Measurements - Carrying Amounts and Estimated Fair Values of the Company’s Debt (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Mark to market adjustment on warrant	$ 20,000	$ 0
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, fair value	361,000		$ 357,000
Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, fair value	351,000		341,000
Pre-delivery credit facility | Carrying Value | Secured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, fair value	133,000		141,000
Pre-delivery credit facility | Estimated Fair Value | Secured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, fair value	131,000		139,000
Floating rate building note | Carrying Value | Secured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, fair value	18,000		18,000
Floating rate building note | Estimated Fair Value | Secured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, fair value	18,000		18,000
Treasury Loan | Carrying Value | Secured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, fair value	150,000		150,000
Treasury Loan | Estimated Fair Value | Secured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, fair value	153,000		148,000
Affinity card advance purchase of mileage credits | Carrying Value | Unsecured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, fair value	15,000		15,000
Affinity card advance purchase of mileage credits | Estimated Fair Value | Unsecured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, fair value	14,000		11,000
PSP Promissory Note
Fair Value Disclosures [Abstract]
Increase to warrant liability	21,000
PSP Promissory Note | Carrying Value | Unsecured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, fair value	45,000		33,000
PSP Promissory Note | Estimated Fair Value | Unsecured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, fair value	$ 35,000		$ 25,000

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Assets and Liabilities Measured at Fair Value (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 429,000	$ 378,000
Warrants	39,000	18,000
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	429,000	378,000
Warrants	0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Warrants	0	0
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Warrants	$ 39,000	$ 18,000

Related Parties (Details)

Related Parties (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Aug. 31, 2018	Mar. 31, 2021USD ($)director	Mar. 31, 2020USD ($)
Indigo Partners | Controladora Vuela Compañía de Aviación, S.A.B. de C.V.
Related Party Transaction [Line Items]
Outstanding shares of common stock held		18.00%
Affiliated Entity | Indigo Partners
Related Party Transaction [Line Items]
Management fees, expense reimbursements, and director compensation | $		$ 1,000	$ 1,000
Affiliated Entity | Controladora Vuela Compañía de Aviación, S.A.B. de C.V.
Related Party Transaction [Line Items]
Number of company directors | director		2
Affiliated Entity | Controladora Vuela Compañía de Aviación, S.A.B. de C.V. | Codeshare Arrangement
Related Party Transaction [Line Items]
Effective period of codeshare agreements	3 years