Spirit Airlines (SAVEQ) 10-Q 23 Oct 19 2019 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Oct. 17, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-35186
Entity Registrant Name	SPIRIT AIRLINES, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	38-1747023
Entity Address, Address Line One	2800 Executive Way
Entity Address, City or Town	Miramar
Entity Address, State or Province	FL
Entity Address, Postal Zip Code	33025
City Area Code	954
Local Phone Number	447-7920
Title of 12(b) Security	Common Stock, $0.0001 par value
Security Exchange Name	NYSE
Trading Symbol	SAVE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		68,448,433
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001498710
Current Fiscal Year End Date	--12-31

Condensed Statements of Operati

Condensed Statements of Operations (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating revenues:
Revenues	$ 991,968	$ 904,330	$ 2,860,720	$ 2,460,239
Operating expenses:
Aircraft fuel	253,847	258,818	748,489	709,644
Salaries, wages and benefits	224,069	185,043	644,345	527,895
Landing fees and other rents	69,142	54,542	193,502	162,774
Aircraft rent	40,026	42,682	132,330	134,618
Depreciation and amortization	57,712	43,773	163,351	128,764
Distribution	39,160	37,868	115,481	103,496
Maintenance, materials and repairs	36,152	37,778	102,444	99,141
Special charges (credits)	0	(686)	0	88,656
Loss on disposal of assets	13,410	1,069	16,873	6,561
Other operating	133,769	98,318	367,482	283,841
Total operating expenses	867,287	759,205	2,484,297	2,245,390
Operating income	124,681	145,125	376,423	214,849
Other (income) expense:
Interest expense	25,138	21,925	75,375	60,272
Capitalized interest	(3,400)	(2,657)	(8,932)	(7,205)
Interest income	(6,292)	(4,776)	(20,282)	(13,272)
Other expense	222	302	599	623
Special charges, non-operating	0	1,744	0	90,357
Total other (income) expense	15,668	16,538	46,760	130,775
Income before income taxes	109,013	128,587	329,663	84,074
Provision for income taxes	25,549	31,107	75,622	20,262
Net income	$ 83,464	$ 97,480	$ 254,041	$ 63,812
Basic earnings per share	$ 1.22	$ 1.43	$ 3.71	$ 0.94
Diluted earnings per share	$ 1.22	$ 1.42	$ 3.71	$ 0.93
Passenger [Member]
Operating revenues:
Revenues	$ 973,353	$ 887,956	$ 2,805,848	$ 2,413,447
Other [Member]
Operating revenues:
Revenues	$ 18,615	$ 16,374	$ 54,872	$ 46,792

Condensed Statements of Compreh

Condensed Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 83,464	$ 97,480	$ 254,041	$ 63,812
Unrealized gain (loss) on short-term investment securities, net of deferred taxes of ($20), ($5), $47, and $21	(68)	(7)	161	70
Interest rate derivative loss reclassified into earnings, net of taxes of $17, $27, $63, and $66	57	52	157	172
Other comprehensive income (loss)	(11)	45	318	242
Comprehensive income	$ 83,453	$ 97,525	$ 254,359	$ 64,054

Condensed Statements of Compr_2

Condensed Statements of Comprehensive Income (Parenthetical) (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Tax effect of the unrealized gain (loss) on short-term investment securities	$ (20)	$ (5)	$ 47	$ 21
Loss reclassified from AOCI into earnings, tax	$ 17	$ 27	$ 63	$ 66

Condensed Balance Sheets (unaud

Condensed Balance Sheets (unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 935,678	$ 1,004,733
Short-term investment securities	104,792	102,789
Accounts receivable, net	71,372	47,660
Aircraft maintenance deposits, net	132,842	106,901
Income tax receivable	21,693	0
Prepaid expenses and other current assets	136,905	83,383
Total current assets	1,403,282	1,345,466
Property and equipment:
Flight equipment	3,549,087	3,257,215
Ground property and equipment	234,740	191,661
Less accumulated depreciation	(450,195)	(332,864)
Total property and equipment	3,333,632	3,116,012
Operating lease right-of-use assets	1,059,766	0
Pre-delivery deposits on flight equipment	330,951	236,775
Long-term aircraft maintenance deposits	79,361	138,738
Deferred heavy maintenance, net	328,109	249,010
Other long-term assets	40,113	79,456
Total assets	6,575,214	5,165,457
Current liabilities:
Accounts payable	41,915	39,320
Air traffic liability	361,218	291,981
Current maturities of long-term debt and finance leases	194,582	163,557
Current maturities of operating leases	117,376	0
Other current liabilities	337,685	339,677
Total current liabilities	1,052,776	834,535
Long-term debt and finance leases, less current maturities	1,968,901	2,024,774
Operating leases, less current maturities	915,977	0
Deferred income taxes	446,940	355,141
Deferred gains and other long-term liabilities	10,533	22,503
Shareholders’ equity:
Common stock	7	7
Additional paid-in-capital	379,354	371,225
Treasury stock, at cost	(72,372)	(67,016)
Retained earnings	1,873,973	1,625,481
Accumulated other comprehensive income (loss)	(875)	(1,193)
Total shareholders’ equity	2,180,087	1,928,504
Total liabilities and shareholders’ equity	$ 6,575,214	$ 5,165,457

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities:
Net income	$ 254,041	$ 63,812
Adjustments to reconcile net income to net cash provided by operations:
Losses reclassified from other comprehensive income	220	238
Share-based compensation	8,128	8,293
Allowance for doubtful accounts (recoveries)	0	(12)
Amortization of deferred gains and losses and debt issuance costs	6,540	6,508
Depreciation and amortization	163,351	128,764
Deferred income tax expense	91,688	21,243
Loss on disposal of assets	16,873	6,561
Special charges, non-operating	0	90,357
Changes in operating assets and liabilities:
Accounts receivable, net	(23,712)	(14,191)
Aircraft maintenance deposits, net	(14,955)	10,543
Prepaid income taxes	1,431	0
Other assets	(24,474)	(5,760)
Deferred heavy maintenance, net	(123,299)	(121,643)
Income tax receivable	(21,693)	(8,662)
Accounts payable	883	38,771
Air traffic liability	69,237	59,916
Other liabilities	(45,169)	23,896
Other	(693)	(136)
Net cash provided by operating activities	358,397	308,498
Investing activities:
Purchase of available-for-sale investment securities	(93,557)	(100,228)
Proceeds from the maturity of available-for-sale investment securities	92,395	99,134
Proceeds from sale of property and equipment	0	9,500
Pre-delivery deposits on flight equipment, net of refunds	(169,200)	(132,297)
Capitalized interest	(7,707)	(6,116)
Assets under construction for others	(7,591)	0
Purchase of property and equipment	(114,396)	(420,586)
Net cash used in investing activities	(300,056)	(550,593)
Financing activities:
Proceeds from issuance of long-term debt	94,706	518,171
Proceeds from stock options exercised	1	5
Payments on debt obligations	(125,914)	(93,225)
Payments on finance lease obligations	(95,608)	(205,566)
Reimbursement for assets under construction for others	5,389	0
Repurchase of common stock	(5,356)	(1,145)
Debt issuance costs	(614)	(3,284)
Net cash (used in) provided by financing activities	(127,396)	214,956
Net decrease in cash and cash equivalents	(69,055)	(27,139)
Cash and cash equivalents at beginning of period	1,004,733	800,849
Cash and cash equivalents at end of period	935,678	773,710
Cash payments for:
Interest, net of capitalized interest	59,840	35,977
Income taxes paid, net of refunds	8,288	3,366
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	141,019	0
Financing cash flows for finance leases	641	0
Non-cash transactions:
Capital expenditures funded by finance lease borrowings	96,371	144,106
Capital expenditures funded by operating lease borrowings	$ 189,487	$ 0

Condensed Statements of Shareho

Condensed Statements of Shareholders' Equity Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Restatement Adjustment [Member]Retained Earnings [Member]
Beginning balance at Dec. 31, 2017	$ 1,762,574	$ 7	$ 360,153	$ (65,854)	$ 1,469,732	$ (1,464)
Share-based compensation	3,075		3,075
Repurchase of common stock	(959)			(959)
Proceeds from options exercised	2		2
Changes in comprehensive income	35					35
Net income	(44,922)
Ending balance at Mar. 31, 2018	1,719,805	7	363,230	(66,813)	1,424,810	(1,429)
Beginning balance at Dec. 31, 2017	1,762,574	7	360,153	(65,854)	1,469,732	(1,464)
Changes in comprehensive income	242
Net income	63,812
Ending balance at Sep. 30, 2018	1,833,782	7	368,452	(66,999)	1,533,544	(1,222)
Beginning balance at Mar. 31, 2018	1,719,805	7	363,230	(66,813)	1,424,810	(1,429)
Share-based compensation	2,306		2,306
Repurchase of common stock	(27)			(27)
Proceeds from options exercised	0		0
Changes in comprehensive income	162					162
Net income	11,254
Ending balance at Jun. 30, 2018	1,733,500	7	365,536	(66,840)	1,436,064	(1,267)
Share-based compensation	2,912		2,912
Repurchase of common stock	(159)			(159)
Proceeds from options exercised	4		4
Changes in comprehensive income	45					45
Net income	97,480
Ending balance at Sep. 30, 2018	1,833,782	7	368,452	(66,999)	1,533,544	(1,222)
Beginning balance at Dec. 31, 2018	1,928,504	7	371,225	(67,016)	1,625,481	(1,193)
Share-based compensation	3,671		3,671
Repurchase of common stock	(5,223)			(5,223)
Proceeds from options exercised	0		0
Changes in comprehensive income	177					177
Net income	56,076
Ending balance at Mar. 31, 2019	1,977,656	7	374,896	(72,239)	1,676,008	(1,016)
Ending balance (Accounting Standards Update 2016-02) at Mar. 31, 2019							$ (5,549)
Beginning balance at Dec. 31, 2018	1,928,504	7	371,225	(67,016)	1,625,481	(1,193)
Changes in comprehensive income	318
Net income	254,041
Ending balance at Sep. 30, 2019	2,180,087	7	379,354	(72,372)	1,873,973	(875)
Beginning balance at Mar. 31, 2019	1,977,656	7	374,896	(72,239)	1,676,008	(1,016)
Share-based compensation	2,742		2,742
Repurchase of common stock	(25)			(25)
Proceeds from options exercised	1		1
Changes in comprehensive income	152					152
Net income	114,501
Ending balance at Jun. 30, 2019	2,095,027	7	377,639	(72,264)	1,790,509	(864)
Share-based compensation	1,715		1,715
Repurchase of common stock	(108)			(108)
Proceeds from options exercised	0		0
Changes in comprehensive income	(11)					(11)
Net income	83,464
Ending balance at Sep. 30, 2019	$ 2,180,087	$ 7	$ 379,354	$ (72,372)	$ 1,873,973	$ (875)

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements include the accounts of Spirit Airlines, Inc. (the "Company"). These unaudited condensed financial statements 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 audited annual financial statements prepared in accordance with U.S. generally accepted accounting principles ("GAAP") have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission for Form 10-Q. These unaudited interim condensed financial statements should be read in conjunction with the audited financial statements of the Company and notes thereto included in the Company's Annual Report on Form 10-K for the year ended December 31, 2018 filed with the Securities and Exchange Commission on February 13, 2019. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect both the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from these estimates.

Recent Accounting Developments

Recent Accounting Developments	9 Months Ended
	Sep. 30, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Developments	Recent Accounting Developments Recently Adopted Accounting Pronouncements Leases The Company adopted ASU No. 2016-02, "Leases (Topic 842)," effective January 1, 2019. The Company adopted Topic 842 utilizing the modified retrospective adoption method with an effective date of January 1, 2019 and elected the package of transition practical expedients for expired or existing contracts, which does not require reassessment of: (1) whether any of the Company's contracts are or contain leases, (2) lease classification and (3) initial direct costs. Therefore, the condensed financial statements for 2019 are presented under the new standard, while the comparative periods presented are not adjusted and continue to be reported in accordance with the Company's historical accounting policy. This standard requires all lessees to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, for all leases with a term greater than 12 months. The adoption of the new lease standard had a significant impact on the Company's condensed balance sheets due to the recognition of $1.0 billion of right-of-use assets for operating leases, $128.1 million of current maturities of operating leases and $895.1 million of operating leases, less current maturities. In addition, the Company recognized a $5.5 million cumulative effect adjustment, net of tax, to retained earnings. This adjustment was driven by the recognition of unamortized deferred gains and losses related to aircraft sale-leaseback transactions entered into in prior periods. Prior to the adoption of Topic 842, gains and losses on sale-leaseback transactions were generally deferred and recognized in income over the lease term. The accounting for finance leases is substantially unchanged. The adoption of Topic 842 did not have a significant impact on the Company's lease classification or a material impact on its statements of operations and liquidity. Additionally, the adoption of Topic 842 did not have a material impact on the Company’s debt-covenant compliance under its current agreements. Refer to Note 10, Leases for information regarding the Company's adoption of Topic 842 and the Company's undiscounted future lease payments and the timing of those payments. Recently Issued Accounting Pronouncements Not Yet Adopted Cloud Computing Arrangements In August 2018, the FASB issued ASU No. 2018-15, "Intangibles - Goodwill and Other - Internal-Use Software." This new standard requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance in Accounting Standards Codification ("ASC") 350-40, "Accounting for Internal-Use Software," to determine which implementation costs to capitalize as assets and amortize over the term of the hosting arrangement or expense as incurred. This standard is effective for the Company for fiscal years, and interim periods within those years, beginning January 1, 2020. Early adoption is permitted, including during an interim period. The Company has elected not to early adopt. Entities have the option to apply this standard prospectively to all implementation costs incurred after the date of adoption or retrospectively. The Company is evaluating this new standard, but does not expect it to have a significant impact on its financial statement presentation or results. Accounting for Credit Losses

Revenue

Revenue	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Revenue Disaggregation	Revenue Operating revenues is comprised of passenger revenues, which includes fare and non-fare revenues, and other revenues. The following table shows disaggregated operating revenues for the three and nine months ended September 30, 2019 and September 30, 2018 . Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (in thousands) Operating revenues: Fare $ 493,376 $ 476,660 $ 1,425,417 $ 1,258,904 Non-fare 479,977 411,296 1,380,431 1,154,543 Total passenger revenues 973,353 887,956 2,805,848 2,413,447 Other 18,615 16,374 54,872 46,792 Total operating revenues $ 991,968 $ 904,330 $ 2,860,720 $ 2,460,239 The Company is managed as a single business unit that provides air transportation for passengers. Operating revenues by geographic region as defined by the Department of Transportation ("DOT") are summarized below: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (in thousands) DOT—Domestic $ 880,868 $ 819,323 $ 2,526,016 $ 2,236,334 DOT—Latin America 111,100 85,007 334,704 223,905 Total $ 991,968 $ 904,330 $ 2,860,720 $ 2,460,239 The Company defers the amount for award travel obligation as part of loyalty deferred revenue within air traffic liability ("ATL") on the Company's condensed balance sheets and recognizes loyalty travel awards in passenger revenues as the mileage credits are used for travel or expire unused. As of September 30, 2019 and December 31, 2018 , the Company had ATL balances of $361.2 million and $292.0 million , respectively. The balance of the Company's ATL is expected to be recognized within 12 months of the respective balance sheet date.

Special Charges

Special Charges	9 Months Ended
	Sep. 30, 2019
Special Charges and Credits [Abstract]
Special Charges	Special Charges Special Charges (Credits), Operating During the nine months ended September 30, 2019 , the Company had no special charges (credits) within operating expenses in the statement of operations. During the first quarter of 2018, the Company negotiated and amended the collective bargaining agreement with the Air Line Pilots Association, International ("ALPA"), under the guidance of the National Mediation Board ("NMB"). In connection with the amended agreement, the Company recorded a one-time ratification incentive of $80.2 million , including payroll taxes, and an $8.5 million adjustment related to other contractual provisions. As a result, the Company recorded $88.7 million in special charges (credits) within operating expenses in the condensed statement of operations for the nine months ended September 30, 2018. Special Charges, Non-Operating During the nine months ended September 30, 2019 , the Company had no special charges, non-operating within other (income) expense in the statement of operations. During the nine months ended September 30, 2018 , the Company recorded $90.4 million in special charges, non-operating within other (income) expense in the statement of operations. During the first quarter of 2018, the Company entered into an aircraft purchase agreement for the purchase of 14 A319 aircraft previously operated under operating leases by the Company. The aggregate gross purchase price for the 14 aircraft was $285.0 million , and the price for each aircraft at the time of the sale was comprised of a cash payment net of the amount of maintenance reserves and security deposits for such aircraft held by the applicable lessor pursuant to the lease for such aircraft. The contract was deemed a lease modification, which resulted in a change of classification from operating leases to finance leases for the 14 aircraft. During the first quarter of 2018, the finance lease assets were recorded at the lower of cost or fair value of the aircraft within flight equipment on the condensed balance sheets. During the second quarter of 2018, the purchase of the 14

Loss on Disposal of Assets

Loss on Disposal of Assets	9 Months Ended
	Sep. 30, 2019
Discontinued Operations and Disposal Groups [Abstract]
Loss on Disposal of Assets	Loss on Disposal of Assets During the nine months ended September 30, 2019 , the Company recorded $16.9 million in loss on disposal of assets in the statement of operations. This loss on disposal of assets consists of $11.6 million related to the disposal of excess and obsolete inventory, $3.1 million related to the write-down of certain held-for-sale assets to fair value less cost to sell and $2.3 million related to the write-off of certain unrecoverable costs previously capitalized with a project to upgrade the Company's enterprise accounting software. This project was suspended in the third quarter of 2019 and the Company has elected to re-evaluate and pursue an alternative solution. Refer to Note 12, Fair Value Measurements for information regarding the Company's held-for-sale assets. These losses were partially offset by a $0.1 million gain on the sale-leaseback transaction for one aircraft in the period. Refer to Note 10, Leases for information regarding the Company's accounting policy on sale-leaseback transactions. During the nine months ended September 30, 2018 , the Company recorded $6.6 million in loss on disposal of assets in the statement of operations. During the second quarter of 2018, the Company sold 5 used engines for $9.5 million at a loss of $4.4 million . In addition, the Company wrote off $2.2 million

Earnings per Share

Earnings per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share The following table sets forth the computation of basic and diluted earnings (loss) per common share: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (in thousands, except per share amounts) Numerator Net income $ 83,464 $ 97,480 $ 254,041 $ 63,812 Denominator Weighted-average shares outstanding, basic 68,442 68,254 68,421 68,243 Effect of dilutive stock awards 103 249 140 103 Adjusted weighted-average shares outstanding, diluted 68,545 68,503 68,561 68,346 Earnings per share Basic earnings per common share $ 1.22 $ 1.43 $ 3.71 $ 0.94 Diluted earnings per common share $ 1.22 $ 1.42 $ 3.71 $ 0.93 Anti-dilutive weighted-average shares 136 5 141 192

Short-term Investment Securitie

Short-term Investment Securities	9 Months Ended
	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]	Short-term Investment Securities The Company's short-term investment securities are classified as available-for-sale and generally consist of U.S. Treasury and U.S. government agency securities with contractual maturities of 12 months or less. These securities are stated at fair value within current assets on the Company's condensed balance sheets. Realized gains and losses on sales of investments, if any, are reflected in non-operating income (expense) in the condensed statements of operations. As of September 30, 2019 and December 31, 2018 , the Company had $104.8 million and $102.8 million in short-term available-for-sale investment securities, respectively. During the nine months ended September 30, 2019 , these investments earned interest income at a weighted-average fixed rate of approximately 2.4% . For the three and nine months ended September 30, 2019 , an unrealized loss of $68 thousand and an unrealized gain of $161 thousand , net of deferred taxes of $20 thousand and $47 thousand , respectively, was recorded within accumulated other comprehensive income ("AOCI") related to these investment securities. For the three and nine months ended September 30, 2018 , an unrealized loss of $7 thousand and an unrealized gain of $70 thousand , net of deferred taxes of $5 thousand and $21 thousand , respectively, was recorded within AOCI related to these investment securities. The Company has not recognized any realized gains or losses related to these securities as the Company has not sold any of these securities. As of September 30, 2019 and December 31, 2018 , $87 thousand and $74 thousand

Accrued Liabilities

Accrued Liabilities	9 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities Other current liabilities as of September 30, 2019 and December 31, 2018 consist of the following: September 30, 2019 December 31, 2018 (in thousands) Salaries and wages $ 82,572 $ 82,900 Federal excise and other passenger taxes and fees payable 68,716 60,604 Airport obligations 65,351 52,029 Aircraft maintenance 30,113 59,805 Aircraft and facility lease obligations 21,807 15,149 Fuel 21,126 25,368 Interest payable 18,753 18,086 Other 29,247 25,736 Other current liabilities $ 337,685 $ 339,677

Financial Instruments and Risk

Financial Instruments and Risk Management	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments and Risk Management	Financial Instruments and Risk Management As part of the Company’s risk management program, the Company from time to time uses a variety of financial instruments to reduce its exposure to fluctuations in the price of jet fuel and in interest rates. The Company does not hold or issue derivative financial instruments for trading purposes. The Company may be exposed to credit losses in the event of nonperformance by counterparties to these financial instruments. The Company periodically reviews and seeks to mitigate exposure to the financial deterioration and nonperformance of any counterparty by monitoring the absolute exposure levels, each counterparty's credit ratings and the historical performance of the counterparties relating to hedge transactions. The credit exposure related to these financial instruments is limited to the fair value of contracts in a net receivable position at the reporting date. The Company also maintains security agreements that require the Company to post collateral if the value of selected instruments falls below specified mark-to-market thresholds. The Company records financial derivative instruments at fair value, which includes an evaluation of each counterparty's credit risk. As of September 30, 2019 , the Company did not hold any derivatives with requirements to post collateral. Fuel Derivative Instruments From time to time, the Company may enter into fuel derivative contracts in order to mitigate the risk of future volatility in fuel prices. The Company's fuel derivative contracts, if any, generally consist of United States Gulf Coast jet fuel swaps ("jet fuel swaps") and United States Gulf Coast jet fuel options ("jet fuel options"). Both jet fuel swaps and jet fuel options are used at times to protect the refining price risk between the price of crude oil and the price of refined jet fuel, and to manage the risk of increasing fuel prices. Fair value of the instruments is determined using standard option valuation models. The Company accounts for any fuel derivative contracts at fair value and recognizes them in the condensed balance sheets in prepaid expenses and other current assets or other current liabilities. The Company did not enter into any fuel derivative instruments during the nine months ended September 30, 2019 and 2018 , and did not have any outstanding fuel derivatives as of September 30, 2019 and December 31, 2018 . Historically, the Company has not elected hedge accounting on any fuel derivative instruments entered into and, as a result, changes in the fair value of fuel derivative contracts, if any, were recorded in aircraft fuel expense. Interest Rate Swaps From time to time, the Company may enter into interest rate swaps to fix the benchmark interest rate component of interest payments or for other reasons. These instruments limit the Company's exposure to changes in the benchmark interest rate in the period from the trade date through the date of maturity. Interest rate swaps may be designated as cash flow hedges. The Company generally accounts for interest rate swaps at fair value and recognizes them in the balance sheet in prepaid expenses and other current assets or other current liabilities with changes in fair value recorded within AOCI. As of September 30, 2019 and December 31, 2018 , the Company did not have any outstanding interest rate swaps. Realized gains and losses from cash flow hedges are recorded in the condensed statements of cash flows as a component of cash flows from operating activities. Subsequent to the issuance of each debt instrument, amounts remaining in AOCI are amortized over the life of the fixed-rate debt instrument. During the nine months ended September 30, 2019 and 2018 , there were no unrealized gains or losses recorded within AOCI related to these instruments as they settled in 2015. For the three and nine months ended September 30, 2019 , the Company reclassified interest rate swap losses of $57 thousand and $157 thousand , net of tax of $17 thousand and $63 thousand , respectively, into earnings. For the three and nine months ended September 30, 2018 , the Company reclassified interest rate swap losses of $52 thousand and $172 thousand , net of tax of $27 thousand and $66 thousand , respectively, into earnings. As of September 30, 2019 and December 31, 2018 , $1.0 million and $1.1 million , net of tax, respectively, remained in AOCI, related to these instruments.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases, Finance	Leases The Company leases aircraft, engines, airport terminals, maintenance and training facilities, aircraft hangars, commercial real estate, and office and computer equipment, among other items. Certain of these leases include provisions for variable lease payments which are based on several factors, including, but not limited to, relative leased square footage, enplaned passengers, and airports’ annual operating budgets. Due to the variable nature of the rates, these leases are not recorded on the Company's condensed balance sheets as a right-of-use asset and lease liability. Lease terms are generally 8 years to 18 years for aircraft and up to 30 years for other leased equipment and property. The Company adopted Topic 842 utilizing the modified retrospective adoption method with an effective date of January 1, 2019. The Company elected not to apply the recognition requirements in Topic 842 to short-term leases (i.e., leases of 12 months or less). Instead, a lessee may recognize the lease payments in profit or loss on a straight-line basis over the lease term. The Company elected this accounting policy for all classes of underlying assets. In addition, in accordance with Topic 842, variable lease payments in the period in which the obligation for those payments is incurred are not included in the recognition of a lease liability or right-of-use asset. Right-of-use assets represent the Company's right to use an underlying asset for the lease term and lease liabilities represent the Company's obligation to make lease payments arising from the lease. Right-of-use assets and liabilities are recognized at the lease commencement date based on the estimated present value of lease payments over the lease term. When available, the Company uses the rate implicit in the lease to discount lease payments to present value. However, the Company's leases generally do not provide a readily determinable implicit rate. Therefore, the Company estimates the incremental borrowing rate to discount lease payments based on information available at lease commencement. The Company uses publicly available data for instruments with similar characteristics when calculating its incremental borrowing rates. The Company has options to extend certain of its operating leases for an additional period of time and options to early terminate several of its operating leases. The lease term consists of the noncancellable period of the lease, periods covered by options to extend the lease if the Company is reasonably certain to exercise the option, periods covered by an option to terminate the lease if the Company is reasonably certain not to exercise the option and periods covered by an option to extend or not terminate the lease in which the exercise of the option is controlled by the lessor. The Company's lease agreements do not contain any residual value guarantees. The Company has elected to not separate non-lease components from the associated lease component for all underlying classes of assets with lease and non-lease components. As of September 30, 2019 , the Company had 47 aircraft financed under operating leases, with lease term expirations between 2022 and 2034 . In addition, as of September 30, 2019 , the Company had 11 spare engines financed under operating leases with lease term expiration dates ranging from 2019 to 2027 . One of the Company's leased aircraft has variable rent payments, which fluctuate based on changes in London Interbank Offered Rate ("LIBOR"). Prior to the adoption of Topic 842, the Company had entered into sale-leaseback transactions with third-party aircraft lessors for some of its leased aircraft and engines. Upon adoption of Topic 842, the Company recognized a $5.5 million cumulative effect adjustment, net of tax, to retained earnings driven by the recognition of unamortized deferred gains and losses related to aircraft sale-leaseback transactions entered into in prior periods. Prior to the adoption of Topic 842, gains and losses on sale-leaseback transactions were generally deferred and recognized in income over the lease term. Under Topic 842, gains and losses on sale-leaseback transactions, subject to adjustment for off-market terms, are recognized immediately and recorded within loss on disposal of assets on the Company's condensed statements of operations. During the nine months ended September 30, 2019 , the Company took delivery of two aircraft under secured debt arrangements, purchased five previously leased aircraft, and took delivery of five aircraft under operating leases. The Company also purchased two engines and purchased one previously leased engine. In addition, the Company entered into a sale-leaseback transaction for one aircraft in the period. With the sale-leaseback transaction, the Company recorded a gain of $0.1 million within loss on disposal of assets on the Company's condensed statements of operations. The sale-leaseback transaction had no off-market terms and therefore no such adjustment was recorded. Upon purchase off lease, the assets previously recorded in our operating lease right-of-use asset (in accordance with the adoption of Topic 842) were recorded within flight equipment on the Company's condensed balance sheets. Some of the Company’s aircraft and engine master lease agreements provide that the Company pays maintenance reserves to aircraft lessors to be held as collateral in advance of the Company’s required performance of major maintenance activities. A majority of these maintenance reserve payments are calculated based on a utilization measure, such as flight hours or cycles, while some maintenance reserve payments are fixed, time-based contractual amounts. Maintenance reserve payments that are probable of being recovered when the Company performs qualifying maintenance are recorded in aircraft maintenance deposits on the Company's condensed balance sheets. Fixed maintenance reserve payments that are not probable of being recovered are considered lease payments and are included in the right-of-use asset and lease liability. Maintenance reserve payments that are based on a utilization measure and are not probable of being recovered are considered variable lease payments that are recognized when they are probable of being incurred and are not included in the right-of-use asset and lease liability. Fixed maintenance reserve payments for the Company's aircraft and related flight equipment, including estimated amounts for contractual price escalations, are expected to be $0.7 million for the remainder of 2019 , $2.6 million in 2020 , $2.6 million in 2021 , $2.7 million in 2022 , $2.5 million in 2023 , and $0.5 million in 2024 and beyond . Some of the master lease agreements do not require that the Company pay maintenance reserves so long as the Company's cash balance does not fall below a certain level. As of September 30, 2019 , the Company is in full compliance with those requirements and does not anticipate having to pay reserves related to these master leases in the future. Under the terms of the lease agreements, the Company will continue to operate and maintain the aircraft. Payments under the majority of the lease agreements are fixed for the term of the lease. The lease agreements contain standard termination events, including termination upon a breach of the Company's obligations to make rental payments and upon any other material breach of the Company's obligations under the leases, and standard maintenance and return condition provisions. These return provisions are evaluated at inception of the lease and throughout the lease terms and are accounted for as either fixed or variable lease payments (depending on the nature of the lease return condition) when it is probable that such amounts will be incurred. When determining probability and estimated cost of lease return obligations, there are various other factors that need to be considered such as the contractual terms of the lease, the ability to swap engines or other aircraft components, current condition of the aircraft, the age of the aircraft at lease expiration, utilization of engines and other components, the extent of repairs needed at return, return locations, current configuration of the aircraft and cost of repairs and materials at the time of return. As a result of the different factors listed above, management assesses the need to accrue lease return costs throughout the lease as facts and circumstances warrant an assessment. The Company expects lease return costs and unrecoverable maintenance deposits will increase as individual aircraft lease agreements approach their respective termination dates and the Company begins to accrue the estimated cost of return conditions for the corresponding aircraft. Upon a termination of the lease due to a breach by the Company, the Company would be liable for standard contractual damages, possibly including damages suffered by the lessor in connection with remarketing the aircraft or while the aircraft is not leased to another party. Aircraft rent expense consists of monthly lease rents for aircraft and spare engines under the terms of the Company's aircraft and spare engine lease agreements recognized on a straight-line basis. Aircraft rent expense also includes maintenance reserves paid to aircraft lessors in advance of the performance of major maintenance activities that are not probable of being reimbursed and probable lease return condition obligations. The following table provides details of the Company's future minimum lease payments under finance lease liabilities and operating lease liabilities recorded on the Company's condensed balance sheets as of September 30, 2019 . The table does not include commitments that are contingent on events or other factors that are currently uncertain or unknown. Finance Leases Operating Leases Aircraft and Spare Engine Leases Property Facility Leases Other Total Operating and Finance Lease Obligations (in thousands) Remainder of 2019 $ 298 $ 45,009 $ 699 $ 145 $ 46,151 2020 780 175,661 2,417 517 179,375 2021 606 174,420 2,131 — 177,157 2022 578 176,203 1,528 — 178,309 2023 202 158,328 1,132 — 159,662 2024 and thereafter — 617,315 4,938 — 622,253 Total minimum lease payments $ 2,464 $ 1,346,936 $ 12,845 $ 662 $ 1,362,907 Less amount representing interest 233 323,560 3,509 21 327,323 Present value of minimum lease payments $ 2,231 $ 1,023,376 $ 9,336 $ 641 $ 1,035,584 Less current portion 814 114,777 2,041 558 118,190 Long-term portion $ 1,417 $ 908,599 $ 7,295 $ 83 $ 917,394 Commitments related to the Company's noncancellable short-term operating leases not recorded on the Company's condensed balance sheets are expected to be $0.5 million for the remainder of 2019 and none in 2020 and beyond . In June 2019, the Company entered into an aircraft sale agreement to acquire four A320 aircraft previously operated by the Company under operating leases. The contract was deemed a lease modification, which resulted in a change of classification from operating leases to finance leases for the four aircraft. The Company recorded a finance lease obligation of $94.9 million calculated as the present value of the remaining lease payments, including the final payment to purchase the aircraft and included within current maturities of long-term debt and finance leases on the Company's condensed balance sheets as of June 30, 2019. In addition, the Company recorded finance lease assets of $140.5 million , which include related amounts previously recorded as maintenance reserves and security deposits and included within flight equipment on the Company's condensed balance sheets as of June 30, 2019. During the third quarter of 2019, the purchase of the four aircraft was completed for an aggregate gross purchase price of $141.3 million , which was comprised of cash payments net of the amount of maintenance reserves and security deposits held by the previous lessor, and the related interest in the amount of $0.3 million was recognized within interest expense on the Company's condensed statements of operations for the nine months ended September 30, 2019 . These aircraft were recorded within flight equipment on the Company's condensed balance sheets. The remainder of the Company's finance lease obligations relate to leased computer and office equipment. Payments under these finance lease agreements are fixed for terms ranging from 3 to 5 years . Accounting for finance leases is substantially unchanged under Topic 842. Finance lease assets are recorded within property and equipment and the related liabilities are recorded within current maturities of long-term debt and finance leases and long-term debt and finance leases, less current maturities in the Company's condensed balance sheets. The table below presents information for lease costs related to the Company's finance and operating leases: Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 (in thousands) Finance lease cost Amortization of leased assets $ 135 $ 863 Interest of lease liabilities 302 641 Operating lease cost Operating lease cost (1) 39,590 137,943 Short-term lease cost (1) 4,218 11,176 Variable lease cost (1) 29,260 89,030 Total lease cost $ 73,505 $ 239,653 (1) Expenses are classified within aircraft rent and landing fees and other rents on the Company's condensed statements of operations. The table below presents lease-related terms and discount rates as of September 30, 2019 : September 30, 2019 Weighted-average remaining lease term Operating leases 9.7 years Finance leases 3.2 years Weighted-average discount rate Operating leases 6.48 % Finance leases 6.14 %
Leases, Operating	Leases The Company leases aircraft, engines, airport terminals, maintenance and training facilities, aircraft hangars, commercial real estate, and office and computer equipment, among other items. Certain of these leases include provisions for variable lease payments which are based on several factors, including, but not limited to, relative leased square footage, enplaned passengers, and airports’ annual operating budgets. Due to the variable nature of the rates, these leases are not recorded on the Company's condensed balance sheets as a right-of-use asset and lease liability. Lease terms are generally 8 years to 18 years for aircraft and up to 30 years for other leased equipment and property. The Company adopted Topic 842 utilizing the modified retrospective adoption method with an effective date of January 1, 2019. The Company elected not to apply the recognition requirements in Topic 842 to short-term leases (i.e., leases of 12 months or less). Instead, a lessee may recognize the lease payments in profit or loss on a straight-line basis over the lease term. The Company elected this accounting policy for all classes of underlying assets. In addition, in accordance with Topic 842, variable lease payments in the period in which the obligation for those payments is incurred are not included in the recognition of a lease liability or right-of-use asset. Right-of-use assets represent the Company's right to use an underlying asset for the lease term and lease liabilities represent the Company's obligation to make lease payments arising from the lease. Right-of-use assets and liabilities are recognized at the lease commencement date based on the estimated present value of lease payments over the lease term. When available, the Company uses the rate implicit in the lease to discount lease payments to present value. However, the Company's leases generally do not provide a readily determinable implicit rate. Therefore, the Company estimates the incremental borrowing rate to discount lease payments based on information available at lease commencement. The Company uses publicly available data for instruments with similar characteristics when calculating its incremental borrowing rates. The Company has options to extend certain of its operating leases for an additional period of time and options to early terminate several of its operating leases. The lease term consists of the noncancellable period of the lease, periods covered by options to extend the lease if the Company is reasonably certain to exercise the option, periods covered by an option to terminate the lease if the Company is reasonably certain not to exercise the option and periods covered by an option to extend or not terminate the lease in which the exercise of the option is controlled by the lessor. The Company's lease agreements do not contain any residual value guarantees. The Company has elected to not separate non-lease components from the associated lease component for all underlying classes of assets with lease and non-lease components. As of September 30, 2019 , the Company had 47 aircraft financed under operating leases, with lease term expirations between 2022 and 2034 . In addition, as of September 30, 2019 , the Company had 11 spare engines financed under operating leases with lease term expiration dates ranging from 2019 to 2027 . One of the Company's leased aircraft has variable rent payments, which fluctuate based on changes in London Interbank Offered Rate ("LIBOR"). Prior to the adoption of Topic 842, the Company had entered into sale-leaseback transactions with third-party aircraft lessors for some of its leased aircraft and engines. Upon adoption of Topic 842, the Company recognized a $5.5 million cumulative effect adjustment, net of tax, to retained earnings driven by the recognition of unamortized deferred gains and losses related to aircraft sale-leaseback transactions entered into in prior periods. Prior to the adoption of Topic 842, gains and losses on sale-leaseback transactions were generally deferred and recognized in income over the lease term. Under Topic 842, gains and losses on sale-leaseback transactions, subject to adjustment for off-market terms, are recognized immediately and recorded within loss on disposal of assets on the Company's condensed statements of operations. During the nine months ended September 30, 2019 , the Company took delivery of two aircraft under secured debt arrangements, purchased five previously leased aircraft, and took delivery of five aircraft under operating leases. The Company also purchased two engines and purchased one previously leased engine. In addition, the Company entered into a sale-leaseback transaction for one aircraft in the period. With the sale-leaseback transaction, the Company recorded a gain of $0.1 million within loss on disposal of assets on the Company's condensed statements of operations. The sale-leaseback transaction had no off-market terms and therefore no such adjustment was recorded. Upon purchase off lease, the assets previously recorded in our operating lease right-of-use asset (in accordance with the adoption of Topic 842) were recorded within flight equipment on the Company's condensed balance sheets. Some of the Company’s aircraft and engine master lease agreements provide that the Company pays maintenance reserves to aircraft lessors to be held as collateral in advance of the Company’s required performance of major maintenance activities. A majority of these maintenance reserve payments are calculated based on a utilization measure, such as flight hours or cycles, while some maintenance reserve payments are fixed, time-based contractual amounts. Maintenance reserve payments that are probable of being recovered when the Company performs qualifying maintenance are recorded in aircraft maintenance deposits on the Company's condensed balance sheets. Fixed maintenance reserve payments that are not probable of being recovered are considered lease payments and are included in the right-of-use asset and lease liability. Maintenance reserve payments that are based on a utilization measure and are not probable of being recovered are considered variable lease payments that are recognized when they are probable of being incurred and are not included in the right-of-use asset and lease liability. Fixed maintenance reserve payments for the Company's aircraft and related flight equipment, including estimated amounts for contractual price escalations, are expected to be $0.7 million for the remainder of 2019 , $2.6 million in 2020 , $2.6 million in 2021 , $2.7 million in 2022 , $2.5 million in 2023 , and $0.5 million in 2024 and beyond . Some of the master lease agreements do not require that the Company pay maintenance reserves so long as the Company's cash balance does not fall below a certain level. As of September 30, 2019 , the Company is in full compliance with those requirements and does not anticipate having to pay reserves related to these master leases in the future. Under the terms of the lease agreements, the Company will continue to operate and maintain the aircraft. Payments under the majority of the lease agreements are fixed for the term of the lease. The lease agreements contain standard termination events, including termination upon a breach of the Company's obligations to make rental payments and upon any other material breach of the Company's obligations under the leases, and standard maintenance and return condition provisions. These return provisions are evaluated at inception of the lease and throughout the lease terms and are accounted for as either fixed or variable lease payments (depending on the nature of the lease return condition) when it is probable that such amounts will be incurred. When determining probability and estimated cost of lease return obligations, there are various other factors that need to be considered such as the contractual terms of the lease, the ability to swap engines or other aircraft components, current condition of the aircraft, the age of the aircraft at lease expiration, utilization of engines and other components, the extent of repairs needed at return, return locations, current configuration of the aircraft and cost of repairs and materials at the time of return. As a result of the different factors listed above, management assesses the need to accrue lease return costs throughout the lease as facts and circumstances warrant an assessment. The Company expects lease return costs and unrecoverable maintenance deposits will increase as individual aircraft lease agreements approach their respective termination dates and the Company begins to accrue the estimated cost of return conditions for the corresponding aircraft. Upon a termination of the lease due to a breach by the Company, the Company would be liable for standard contractual damages, possibly including damages suffered by the lessor in connection with remarketing the aircraft or while the aircraft is not leased to another party. Aircraft rent expense consists of monthly lease rents for aircraft and spare engines under the terms of the Company's aircraft and spare engine lease agreements recognized on a straight-line basis. Aircraft rent expense also includes maintenance reserves paid to aircraft lessors in advance of the performance of major maintenance activities that are not probable of being reimbursed and probable lease return condition obligations. The following table provides details of the Company's future minimum lease payments under finance lease liabilities and operating lease liabilities recorded on the Company's condensed balance sheets as of September 30, 2019 . The table does not include commitments that are contingent on events or other factors that are currently uncertain or unknown. Finance Leases Operating Leases Aircraft and Spare Engine Leases Property Facility Leases Other Total Operating and Finance Lease Obligations (in thousands) Remainder of 2019 $ 298 $ 45,009 $ 699 $ 145 $ 46,151 2020 780 175,661 2,417 517 179,375 2021 606 174,420 2,131 — 177,157 2022 578 176,203 1,528 — 178,309 2023 202 158,328 1,132 — 159,662 2024 and thereafter — 617,315 4,938 — 622,253 Total minimum lease payments $ 2,464 $ 1,346,936 $ 12,845 $ 662 $ 1,362,907 Less amount representing interest 233 323,560 3,509 21 327,323 Present value of minimum lease payments $ 2,231 $ 1,023,376 $ 9,336 $ 641 $ 1,035,584 Less current portion 814 114,777 2,041 558 118,190 Long-term portion $ 1,417 $ 908,599 $ 7,295 $ 83 $ 917,394 Commitments related to the Company's noncancellable short-term operating leases not recorded on the Company's condensed balance sheets are expected to be $0.5 million for the remainder of 2019 and none in 2020 and beyond . In June 2019, the Company entered into an aircraft sale agreement to acquire four A320 aircraft previously operated by the Company under operating leases. The contract was deemed a lease modification, which resulted in a change of classification from operating leases to finance leases for the four aircraft. The Company recorded a finance lease obligation of $94.9 million calculated as the present value of the remaining lease payments, including the final payment to purchase the aircraft and included within current maturities of long-term debt and finance leases on the Company's condensed balance sheets as of June 30, 2019. In addition, the Company recorded finance lease assets of $140.5 million , which include related amounts previously recorded as maintenance reserves and security deposits and included within flight equipment on the Company's condensed balance sheets as of June 30, 2019. During the third quarter of 2019, the purchase of the four aircraft was completed for an aggregate gross purchase price of $141.3 million , which was comprised of cash payments net of the amount of maintenance reserves and security deposits held by the previous lessor, and the related interest in the amount of $0.3 million was recognized within interest expense on the Company's condensed statements of operations for the nine months ended September 30, 2019 . These aircraft were recorded within flight equipment on the Company's condensed balance sheets. The remainder of the Company's finance lease obligations relate to leased computer and office equipment. Payments under these finance lease agreements are fixed for terms ranging from 3 to 5 years . Accounting for finance leases is substantially unchanged under Topic 842. Finance lease assets are recorded within property and equipment and the related liabilities are recorded within current maturities of long-term debt and finance leases and long-term debt and finance leases, less current maturities in the Company's condensed balance sheets. The table below presents information for lease costs related to the Company's finance and operating leases: Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 (in thousands) Finance lease cost Amortization of leased assets $ 135 $ 863 Interest of lease liabilities 302 641 Operating lease cost Operating lease cost (1) 39,590 137,943 Short-term lease cost (1) 4,218 11,176 Variable lease cost (1) 29,260 89,030 Total lease cost $ 73,505 $ 239,653 (1) Expenses are classified within aircraft rent and landing fees and other rents on the Company's condensed statements of operations. The table below presents lease-related terms and discount rates as of September 30, 2019 : September 30, 2019 Weighted-average remaining lease term Operating leases 9.7 years Finance leases 3.2 years Weighted-average discount rate Operating leases 6.48 % Finance leases 6.14 %

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Aircraft-Related Commitments and Financing Arrangements The Company’s contractual purchase commitments consist primarily of aircraft and engine acquisitions through manufacturers and aircraft leasing companies. As of September 30, 2019 , the Company's aircraft orders consisted of the following: Airbus Third-Party Lessor A320neo A320ceo A320neo Total Remainder of 2019 7 2 0 9 2020 15 0 5 20 2021 20 0 7 27 42 2 12 56 As of September 30, 2019 , the Company has no contractual aircraft purchase commitments beyond 2021. The Company also has one spare engine order for a V2500 SelectTwo engine with International Aero Engines ("IAE") and six spare engine orders for PurePower PW1100G-JM engines with Pratt & Whitney. Spare engines are scheduled for delivery from 2020 through 2023 . Purchase commitments for these aircraft and engines, including estimated amounts for contractual price escalations and pre-delivery payments, are expected to be $308.1 million for the remainder of 2019 , $858.1 million in 2020 , $776.1 million in 2021 , $17.6 million in 2022 , $8.3 million in 2023 , and none in 2024 and beyond . As of September 30, 2019 , the Company has secured sale-leaseback financing commitments for five aircraft being delivered from Airbus in the remainder of 2019. As of September 30, 2019 , the Company does not have financing commitments in place for the remaining 37 Airbus aircraft on firm order, which are scheduled for delivery in the remainder of 2019 through 2021 . Aircraft rent commitments for future aircraft deliveries to be financed under direct leases from third-party lessors are expected to be approximately $0.8 million for the remainder of 2019, $15.0 million in 2020, $42.0 million in 2021, $47.8 million in 2022, $47.8 million in 2023, and $420.4 million in 2024 and beyond. In October 2019, the Company reached a memorandum of understanding with Airbus for the purchase of 100 new Airbus A320neo family aircraft with the option to purchase up to an additional 50 aircraft. The aircraft would be scheduled for delivery between 2022 and 2027. The memorandum is subject to finalization in the purchase agreement. Interest commitments related to the secured debt financing of 62 delivered aircraft as of September 30, 2019 are $22.7 million for the remainder of 2019 , $78.5 million in 2020 , $71.3 million in 2021 , $64.3 million in 2022 , $54.1 million in 2023 , and $157.9 million in 2024 and beyond . For principal commitments related to these financed aircraft, refer to Note 13, Debt and Other Obligations. The Company is contractually obligated to pay the following minimum guaranteed payments for its reservation system and other miscellaneous subscriptions and services as of September 30, 2019 : $3.4 million for the remainder of 2019 , $17.5 million in 2020 , $14.7 million in 2021 , $13.9 million in 2022 , $12.7 million in 2023 , and $60.1 million thereafter . During the first quarter of 2018, the Company entered into a contract renewal with its reservation system provider which expires in 2028. On October 17, 2019, the Company announced its intention to build a headquarter campus in Dania Beach, Florida of up to 500,000 square feet by 2022. The Company entered into an agreement in principle to secure the land and expects to have a finalized, definitive agreement by December 2019. The Company estimates the total capital outlay for the project will be approximately $250 million over 36 months. Litigation 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 believes the ultimate outcome of such lawsuits, proceedings and reviews will not, individually or in the aggregate, have a material adverse effect on its financial position, liquidity or results of operations. Credit Card Processing Arrangements The Company has agreements with organizations that process credit card transactions arising from the purchase of air travel, baggage charges, and other ancillary services by customers. As is standard in the airline industry, the Company's contractual arrangements with credit card processors permit them, under certain circumstances, to retain a holdback or other collateral, which the Company records as restricted cash, when future air travel and other future services are purchased via credit card transactions. The required holdback is the percentage of the Company's overall credit card sales that its credit card processors hold to cover refunds to customers if the Company fails to fulfill its flight obligations. The Company's credit card processors do not require the Company to maintain cash collateral provided that the Company satisfies certain liquidity and other financial covenants. Failure to meet these covenants would provide the processors the right to place a holdback resulting in a commensurate reduction of unrestricted cash. As of September 30, 2019 and December 31, 2018 , the Company was in compliance with such liquidity and other financial covenants in its credit card processing agreements and the processors were holding back no remittances. The maximum potential exposure to cash holdbacks by the Company's credit card processors, based upon advance ticket sales and $9 Fare Club memberships as of September 30, 2019 and December 31, 2018 , was $399.0 million and $321.0 million , respectively. Employees The Company has 5 union-represented employee groups that together represented approximately 80% of all employees as of September 30, 2019 . The table below sets forth the Company's employee groups and status of the collective bargaining agreements as of September 30, 2019 . Employee Groups Representative Amendable Date Percentage of Workforce Pilots Air Line Pilots Association, International ("ALPA") February 2023 26% Flight Attendants Association of Flight Attendants ("AFA-CWA") May 2021 46% Dispatchers Professional Airline Flight Control Association ("PAFCA") October 2023 1% Ramp Service Agents International Association of Machinists and Aerospace Workers ("IAMAW") June 2020 3% Passenger Service Agents Transport Workers Union of America ("TWU") NA 3% In August 2015 , the Company's collective bargaining agreement with its pilots, represented by ALPA, became amendable. In February 2018, the pilot group voted to approve a new five -year agreement with the Company. In connection with the new agreement, the Company recorded a one-time ratification incentive of $80.2 million , including payroll taxes, and an $8.5 million adjustment related to other contractual provisions. These amounts were recorded in special charges (credits) within operating expenses in the condensed statements of operations for the nine months ended September 30, 2018 . For additional information, refer to Note 4, Special Charges. In June 2018, the NMB notified the Company that the TWU filed an application seeking a representation election for the Company's passenger service agents. The NMB determined that a representation election would be held and the voting period for the election took place through September 4, 2018. The Company’s passenger service agents voted to be represented by the TWU, but the representation applies only to the Company’s Fort Lauderdale station where the Company has direct employees in the passenger service classification. The Company and the TWU began meeting in late October 2018 to negotiate an initial collective bargaining agreement. As of September 30, 2019 , the Company continued to negotiate with the TWU. The Company is self-insured for healthcare claims, up to a stop-loss amount for eligible participating employees and qualified dependent medical 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 $4.7 million and $4.4 million in health care claims as of September 30, 2019 and December 31, 2018 , respectively.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
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 the Company’s financial assets and liabilities. Fuel Derivative Instruments From time to time, the Company may enter into fuel derivative contracts in order to mitigate the risk of future volatility in fuel prices. The Company’s fuel derivative contracts generally consist of jet fuel swaps and jet fuel options. These instruments are valued using energy and commodity market data, which is derived by combining raw inputs with quantitative models and processes to generate forward curves and volatilities. The Company utilizes the market approach to measure fair value for its fuel derivative instruments, if any. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities. The Company has not historically elected hedge accounting on its fuel derivative instruments, if any. As a result, the Company would record the fair value adjustment of any fuel derivatives in the accompanying condensed statements of operations within aircraft fuel and on the condensed balance sheets within prepaid expenses and other current assets or other current liabilities, depending on whether the net fair value of the derivatives is in an asset or liability position as of the respective date. Fair values of any fuel derivative instruments are determined using standard option valuation models. The Company also considers counterparty risk and its own credit risk in its determination of all estimated fair values. The Company offsets fair value amounts recognized for any derivative instruments executed with the same counterparty under a master netting arrangement. The Company determines fair value of any jet fuel options utilizing an option pricing model based on inputs that are either readily available in public markets or can be derived from information available in publicly quoted markets. The Company has consistently applied these valuation techniques in all periods presented and believes it has obtained the most accurate information available for the types of derivative contracts it may hold. The fair value of the Company's jet fuel swaps, if any, are determined based on inputs that are readily available in public markets or can be derived from information available in publicly quoted markets; therefore, the Company categorizes these instruments as Level 2. Due to the fact that certain inputs utilized to determine the fair value of jet fuel options are unobservable (principally implied volatility), the Company categorizes these derivatives as Level 3. Implied volatility of a jet fuel option is the volatility of the price of the underlying commodity that is implied by the market price of the option based on an option pricing model. Thus, it is the volatility that when used in a particular pricing model yields a theoretical value for the option equal to the current market price of that option. Implied volatility, a forward-looking measure, differs from historical volatility because the latter is calculated from known past returns. At each balance sheet date, the Company substantiates and adjusts unobservable inputs. The Company routinely assesses the valuation model's sensitivity to changes in implied volatility. As of September 30, 2019 and December 31, 2018 , the Company had no outstanding jet fuel derivatives. Long-Term Debt The estimated fair value of the Company's term loan debt agreements and revolving credit facility have been determined to be Level 3 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 estimated fair value of the Company's publicly and non-publicly held EETC debt agreements has been determined to be Level 2 as the Company utilizes quoted market prices in markets with low trading volumes to estimate the fair value of its Level 2 long-term debt. The carrying amounts and estimated fair values of the Company's long-term debt at September 30, 2019 and December 31, 2018 were as follows: September 30, 2019 December 31, 2018 Fair Value Level Hierarchy Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value (in millions) Fixed-rate senior term loans $ 354.7 $ 378.0 $ 382.4 $ 373.6 Level 3 Fixed-rate junior term loans 24.6 25.3 31.1 31.1 Level 3 Fixed-rate term loans 660.0 699.6 625.1 600.1 Level 3 2015-1 EETC Class A 363.6 383.6 378.6 374.8 Level 2 2015-1 EETC Class B 76.0 78.8 80.0 78.1 Level 2 2015-1 EETC Class C 103.8 106.4 109.5 107.9 Level 2 2017-1 EETC Class AA 228.4 237.5 242.5 228.8 Level 2 2017-1 EETC Class A 76.1 78.4 80.8 76.6 Level 2 2017-1 EETC Class B 70.6 71.5 83.7 79.1 Level 2 2017-1 EETC Class C 85.5 88.0 85.5 84.2 Level 2 Revolving credit facility 160.0 160.0 135.3 135.3 Level 3 Total long-term debt $ 2,203.3 $ 2,307.1 $ 2,234.5 $ 2,169.6 Cash and Cash Equivalents Cash and cash equivalents at September 30, 2019 and December 31, 2018 are comprised of liquid money market funds and cash, and are categorized as Level 1 instruments. The Company maintains cash with various high-quality financial institutions. Short-term Investment Securities Short-term investment securities at September 30, 2019 and December 31, 2018 are classified as available-for-sale and generally consist of U.S. Treasury and U.S. government agency securities with contractual maturities of 12 months or less. The Company's short-term investment securities are categorized as Level 1 instruments, as the Company uses quoted market prices in active markets when determining the fair value of these securities. For additional information, refer to Note 7, Short-term Investment Securities. Assets Held for Sale The Company's assets held for sale consist of rotable aircraft parts. When long-lived assets are identified as held for sale and the required criteria are met, the Company reclassifies the assets from property and equipment to prepaid expenses and other current assets on the Company's condensed balance sheets and discontinues depreciation. The assets are measured at the lower of the carrying amount or fair value less cost to sell and a loss is recognized for any initial adjustment of the asset’s carrying amount to fair value less cost to sell. Such valuations include estimations of fair values and incremental direct costs to transact a sale. The fair value measurements for our held-for-sale assets were based on Level 3 inputs, which include information obtained from third-party valuation sources. During the third quarter of 2019, the Company recorded $2.3 million in assets held for sale at fair value less cost to sell. Assets and liabilities measured at gross fair value on a recurring basis are summarized below: Fair Value Measurements as of September 30, 2019 Total Level Level Level (in millions) Cash and cash equivalents $ 935.7 $ 935.7 $ — $ — Short-term investment securities 104.8 104.8 — — Assets held for sale 2.3 — — 2.3 Total assets $ 1,042.8 $ 1,040.5 $ — $ 2.3 Total liabilities $ — $ — $ — $ — Fair Value Measurements as of December 31, 2018 Total Level Level Level (in millions) Cash and cash equivalents $ 1,004.7 $ 1,004.7 $ — $ — Short-term investment securities 102.8 102.8 — — Total assets $ 1,107.5 $ 1,107.5 $ — $ — Total liabilities $ — $ — $ — $ — The Company had no transfers of assets or liabilities between any of the above levels during the periods ended September 30, 2019 and December 31, 2018 .

Debt and Other Obligations

Debt and Other Obligations	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt and Other Obligations	Debt and Other Obligations As of September 30, 2019 , the Company had outstanding non-public and public debt instruments. During the nine months ended September 30, 2019 , the Company incurred debt through fixed-rate term loans and a previously existing revolving credit facility described below. Fixed-rate term loans During 2018, the Company entered into a facility agreement, which as of September 30, 2019 , provided $70.0 million for two Airbus A320 aircraft delivered in 2019. The loans extended under the facility agreement are secured by a first-priority security interest on the individual aircraft. These loans have a term life of 12 years and amortize on a mortgage-style basis, which requires quarterly principal and interest payments. Revolving credit facility During 2018, the Company entered into a revolving credit facility for up to $160.0 million secured by the collateral assignment of certain of the Company's rights under the purchase agreement with Airbus. As of September 30, 2019 , collateralized amounts were related to 40 Airbus A320neo aircraft scheduled to be delivered between November 2019 and December 2021. The final maturity of the facility is December 30, 2020. As of September 30, 2019 , the Company had drawn $160.0 million on the facility which is included in long-term debt and finance leases, less current maturities on the Company's condensed balance sheets. The revolving credit facility bears variable interest based on LIBOR. Long-term debt is comprised of the following: As of As of September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 (in millions) (weighted-average interest rates) Fixed-rate senior term loans due through 2027 $ 354.7 $ 382.4 4.10 % 4.10 % Fixed-rate junior term loans due through 2022 24.6 31.1 6.90 % 6.90 % Fixed-rate loans due through 2031 660.0 625.1 3.48 % 3.88 % Fixed-rate class A 2015-1 EETC due through 2028 363.6 378.6 4.10 % 4.10 % Fixed-rate class B 2015-1 EETC due through 2024 76.0 80.0 4.45 % 4.45 % Fixed-rate class C 2015-1 EETC due through 2023 103.8 109.5 4.93 % 4.93 % Fixed-rate class AA 2017-1 EETC due through 2030 228.4 242.5 3.38 % 3.38 % Fixed-rate class A 2017-1 EETC due through 2030 76.1 80.8 3.65 % 3.65 % Fixed-rate class B 2017-1 EETC due through 2026 70.6 83.7 3.80 % 3.80 % Fixed-rate class C 2017-1 EETC due through 2023 85.5 85.5 5.11 % 5.11 % Revolving credit facility due in 2020 160.0 135.3 3.45 % 3.72 % Long-term debt 2,203.3 2,234.5 Less current maturities 193.7 162.8 Less unamortized discounts, net 42.0 47.7 Total $ 1,967.6 $ 2,024.0 The Company's debt financings are collateralized by first priority security interest in the individual aircraft being financed with the exception of the Company's revolving credit facility secured by the Company's rights under the purchase agreement with Airbus related to certain A320neo aircraft. During the three and nine months ended September 30, 2019 , the Company made scheduled principal payments of $40.1 million and $125.9 million , respectively, on its outstanding debt obligations. During the three and nine months ended September 30, 2018 , the Company made scheduled principal payments of $32.6 million and $93.2 million , respectively, on its outstanding debt obligations. At September 30, 2019 , long-term debt principal payments for the next five years and thereafter are as follows: September 30, 2019 (in millions) Remainder of 2019 $ 49.3 2020 221.1 2021 280.8 2022 164.3 2023 303.1 2024 and beyond 1,184.7 Total debt principal payments $ 2,203.3 Interest Expense Interest expense related to long-term debt and finance leases consists of the following: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (in thousands) Fixed-rate senior term loans $ 3,809 $ 4,195 $ 11,632 $ 12,769 Fixed-rate junior term loans 454 605 1,467 1,908 Fixed-rate term loans 6,517 4,844 19,151 14,636 Class A 2015-1 EETC 3,747 4,057 11,294 12,214 Class B 2015-1 EETC 850 939 2,570 2,881 Class C 2015-1 EETC 1,279 1,420 3,894 2,209 Class AA 2017-1 EETC 1,973 1,751 5,959 4,008 Class A 2017-1 EETC 711 631 2,148 1,445 Class B 2017-1 EETC 708 700 2,199 1,636 Class C 2017-1 EETC 1,104 934 3,275 1,400 Revolving credit facility 1,493 — 4,466 — Amortization of deferred financing costs 2,175 1,784 6,544 4,930 Commitment and other fees 281 49 400 182 Finance leases 37 16 376 54 Total $ 25,138 $ 21,925 $ 75,375 $ 60,272

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events In October 2019, the United States government imposed tariffs on certain imports from the European Union, including a 10% tariff on new Airbus aircraft and related parts. The Company is currently evaluating the impact of the tariffs on the cost and timing of future aircraft deliveries. Please refer to "Part II. Other Information—Item 1A. Risk Factors" for further discussion on this topic.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of accounting	The accompanying unaudited condensed financial statements include the accounts of Spirit Airlines, Inc. (the "Company"). These unaudited condensed financial statements 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 audited annual financial statements prepared in accordance with U.S. generally accepted accounting principles ("GAAP") have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission for Form 10-Q. These unaudited interim condensed financial statements should be read in conjunction with the audited financial statements of the Company and notes thereto included in the Company's Annual Report on Form 10-K for the year ended December 31, 2018
Use of estimates	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect both the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from these estimates.
Recent Accounting Developments	Recently Adopted Accounting Pronouncements Leases The Company adopted ASU No. 2016-02, "Leases (Topic 842)," effective January 1, 2019. The Company adopted Topic 842 utilizing the modified retrospective adoption method with an effective date of January 1, 2019 and elected the package of transition practical expedients for expired or existing contracts, which does not require reassessment of: (1) whether any of the Company's contracts are or contain leases, (2) lease classification and (3) initial direct costs. Therefore, the condensed financial statements for 2019 are presented under the new standard, while the comparative periods presented are not adjusted and continue to be reported in accordance with the Company's historical accounting policy. This standard requires all lessees to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, for all leases with a term greater than 12 months. The adoption of the new lease standard had a significant impact on the Company's condensed balance sheets due to the recognition of $1.0 billion of right-of-use assets for operating leases, $128.1 million of current maturities of operating leases and $895.1 million of operating leases, less current maturities. In addition, the Company recognized a $5.5 million cumulative effect adjustment, net of tax, to retained earnings. This adjustment was driven by the recognition of unamortized deferred gains and losses related to aircraft sale-leaseback transactions entered into in prior periods. Prior to the adoption of Topic 842, gains and losses on sale-leaseback transactions were generally deferred and recognized in income over the lease term. The accounting for finance leases is substantially unchanged. The adoption of Topic 842 did not have a significant impact on the Company's lease classification or a material impact on its statements of operations and liquidity. Additionally, the adoption of Topic 842 did not have a material impact on the Company’s debt-covenant compliance under its current agreements. Refer to Note 10, Leases for information regarding the Company's adoption of Topic 842 and the Company's undiscounted future lease payments and the timing of those payments. Recently Issued Accounting Pronouncements Not Yet Adopted Cloud Computing Arrangements In August 2018, the FASB issued ASU No. 2018-15, "Intangibles - Goodwill and Other - Internal-Use Software." This new standard requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance in Accounting Standards Codification ("ASC") 350-40, "Accounting for Internal-Use Software," to determine which implementation costs to capitalize as assets and amortize over the term of the hosting arrangement or expense as incurred. This standard is effective for the Company for fiscal years, and interim periods within those years, beginning January 1, 2020. Early adoption is permitted, including during an interim period. The Company has elected not to early adopt. Entities have the option to apply this standard prospectively to all implementation costs incurred after the date of adoption or retrospectively. The Company is evaluating this new standard, but does not expect it to have a significant impact on its financial statement presentation or results. Accounting for Credit Losses
Sale Leaseback Transactions	Prior to the adoption of Topic 842, gains and losses on sale-leaseback transactions were generally deferred and recognized in income over the lease term. Under Topic 842, gains and losses on sale-leaseback transactions, subject to adjustment for off-market terms, are recognized immediately and recorded within loss on disposal of assets on the Company's condensed statements of operations.
Leases	Aircraft rent expense consists of monthly lease rents for aircraft and spare engines under the terms of the Company's aircraft and spare engine lease agreements recognized on a straight-line basis. Aircraft rent expense also includes maintenance reserves paid to aircraft lessors in advance of the performance of major maintenance activities that are not probable of being reimbursed and probable lease return condition obligations.

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Schedule of Revenue Disaggregation	The following table shows disaggregated operating revenues for the three and nine months ended September 30, 2019 and September 30, 2018 . Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (in thousands) Operating revenues: Fare $ 493,376 $ 476,660 $ 1,425,417 $ 1,258,904 Non-fare 479,977 411,296 1,380,431 1,154,543 Total passenger revenues 973,353 887,956 2,805,848 2,413,447 Other 18,615 16,374 54,872 46,792 Total operating revenues $ 991,968 $ 904,330 $ 2,860,720 $ 2,460,239 Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (in thousands) DOT—Domestic $ 880,868 $ 819,323 $ 2,526,016 $ 2,236,334 DOT—Latin America 111,100 85,007 334,704 223,905 Total $ 991,968 $ 904,330 $ 2,860,720 $ 2,460,239

Earnings per Share (Tables)

Earnings per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Computation of basic and diluted earnings per common share	The following table sets forth the computation of basic and diluted earnings (loss) per common share: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (in thousands, except per share amounts) Numerator Net income $ 83,464 $ 97,480 $ 254,041 $ 63,812 Denominator Weighted-average shares outstanding, basic 68,442 68,254 68,421 68,243 Effect of dilutive stock awards 103 249 140 103 Adjusted weighted-average shares outstanding, diluted 68,545 68,503 68,561 68,346 Earnings per share Basic earnings per common share $ 1.22 $ 1.43 $ 3.71 $ 0.94 Diluted earnings per common share $ 1.22 $ 1.42 $ 3.71 $ 0.93 Anti-dilutive weighted-average shares 136 5 141 192

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	9 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Accrued liabilities included in other current liabilities	Other current liabilities as of September 30, 2019 and December 31, 2018 consist of the following: September 30, 2019 December 31, 2018 (in thousands) Salaries and wages $ 82,572 $ 82,900 Federal excise and other passenger taxes and fees payable 68,716 60,604 Airport obligations 65,351 52,029 Aircraft maintenance 30,113 59,805 Aircraft and facility lease obligations 21,807 15,149 Fuel 21,126 25,368 Interest payable 18,753 18,086 Other 29,247 25,736 Other current liabilities $ 337,685 $ 339,677

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Schedule of Operating Lease Maturities	The following table provides details of the Company's future minimum lease payments under finance lease liabilities and operating lease liabilities recorded on the Company's condensed balance sheets as of September 30, 2019 . The table does not include commitments that are contingent on events or other factors that are currently uncertain or unknown. Finance Leases Operating Leases Aircraft and Spare Engine Leases Property Facility Leases Other Total Operating and Finance Lease Obligations (in thousands) Remainder of 2019 $ 298 $ 45,009 $ 699 $ 145 $ 46,151 2020 780 175,661 2,417 517 179,375 2021 606 174,420 2,131 — 177,157 2022 578 176,203 1,528 — 178,309 2023 202 158,328 1,132 — 159,662 2024 and thereafter — 617,315 4,938 — 622,253 Total minimum lease payments $ 2,464 $ 1,346,936 $ 12,845 $ 662 $ 1,362,907 Less amount representing interest 233 323,560 3,509 21 327,323 Present value of minimum lease payments $ 2,231 $ 1,023,376 $ 9,336 $ 641 $ 1,035,584 Less current portion 814 114,777 2,041 558 118,190 Long-term portion $ 1,417 $ 908,599 $ 7,295 $ 83 $ 917,394
Schedule of Finance Lease Maturities	The following table provides details of the Company's future minimum lease payments under finance lease liabilities and operating lease liabilities recorded on the Company's condensed balance sheets as of September 30, 2019 . The table does not include commitments that are contingent on events or other factors that are currently uncertain or unknown. Finance Leases Operating Leases Aircraft and Spare Engine Leases Property Facility Leases Other Total Operating and Finance Lease Obligations (in thousands) Remainder of 2019 $ 298 $ 45,009 $ 699 $ 145 $ 46,151 2020 780 175,661 2,417 517 179,375 2021 606 174,420 2,131 — 177,157 2022 578 176,203 1,528 — 178,309 2023 202 158,328 1,132 — 159,662 2024 and thereafter — 617,315 4,938 — 622,253 Total minimum lease payments $ 2,464 $ 1,346,936 $ 12,845 $ 662 $ 1,362,907 Less amount representing interest 233 323,560 3,509 21 327,323 Present value of minimum lease payments $ 2,231 $ 1,023,376 $ 9,336 $ 641 $ 1,035,584 Less current portion 814 114,777 2,041 558 118,190 Long-term portion $ 1,417 $ 908,599 $ 7,295 $ 83 $ 917,394
Schedule of Lease Cost	The table below presents information for lease costs related to the Company's finance and operating leases: Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 (in thousands) Finance lease cost Amortization of leased assets $ 135 $ 863 Interest of lease liabilities 302 641 Operating lease cost Operating lease cost (1) 39,590 137,943 Short-term lease cost (1) 4,218 11,176 Variable lease cost (1) 29,260 89,030 Total lease cost $ 73,505 $ 239,653 (1) Expenses are classified within aircraft rent and landing fees and other rents on the Company's condensed statements of operations. The table below presents lease-related terms and discount rates as of September 30, 2019 : September 30, 2019 Weighted-average remaining lease term Operating leases 9.7 years Finance leases 3.2 years Weighted-average discount rate Operating leases 6.48 % Finance leases 6.14 %

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Operating Aircraft Leases	As of September 30, 2019 , the Company's aircraft orders consisted of the following: Airbus Third-Party Lessor A320neo A320ceo A320neo Total Remainder of 2019 7 2 0 9 2020 15 0 5 20 2021 20 0 7 27 42 2 12 56
Employee groups and status of the collective bargaining agreements	The table below sets forth the Company's employee groups and status of the collective bargaining agreements as of September 30, 2019 . Employee Groups Representative Amendable Date Percentage of Workforce Pilots Air Line Pilots Association, International ("ALPA") February 2023 26% Flight Attendants Association of Flight Attendants ("AFA-CWA") May 2021 46% Dispatchers Professional Airline Flight Control Association ("PAFCA") October 2023 1% Ramp Service Agents International Association of Machinists and Aerospace Workers ("IAMAW") June 2020 3% Passenger Service Agents Transport Workers Union of America ("TWU") NA 3%

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Carrying amount and estimated fair value, long-term debt	The carrying amounts and estimated fair values of the Company's long-term debt at September 30, 2019 and December 31, 2018 were as follows: September 30, 2019 December 31, 2018 Fair Value Level Hierarchy Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value (in millions) Fixed-rate senior term loans $ 354.7 $ 378.0 $ 382.4 $ 373.6 Level 3 Fixed-rate junior term loans 24.6 25.3 31.1 31.1 Level 3 Fixed-rate term loans 660.0 699.6 625.1 600.1 Level 3 2015-1 EETC Class A 363.6 383.6 378.6 374.8 Level 2 2015-1 EETC Class B 76.0 78.8 80.0 78.1 Level 2 2015-1 EETC Class C 103.8 106.4 109.5 107.9 Level 2 2017-1 EETC Class AA 228.4 237.5 242.5 228.8 Level 2 2017-1 EETC Class A 76.1 78.4 80.8 76.6 Level 2 2017-1 EETC Class B 70.6 71.5 83.7 79.1 Level 2 2017-1 EETC Class C 85.5 88.0 85.5 84.2 Level 2 Revolving credit facility 160.0 160.0 135.3 135.3 Level 3 Total long-term debt $ 2,203.3 $ 2,307.1 $ 2,234.5 $ 2,169.6
Schedule of assets and liabilities measured at fair value on a recurring basis	Assets and liabilities measured at gross fair value on a recurring basis are summarized below: Fair Value Measurements as of September 30, 2019 Total Level Level Level (in millions) Cash and cash equivalents $ 935.7 $ 935.7 $ — $ — Short-term investment securities 104.8 104.8 — — Assets held for sale 2.3 — — 2.3 Total assets $ 1,042.8 $ 1,040.5 $ — $ 2.3 Total liabilities $ — $ — $ — $ — Fair Value Measurements as of December 31, 2018 Total Level Level Level (in millions) Cash and cash equivalents $ 1,004.7 $ 1,004.7 $ — $ — Short-term investment securities 102.8 102.8 — — Total assets $ 1,107.5 $ 1,107.5 $ — $ — Total liabilities $ — $ — $ — $ —

Debt and Other Obligations (Tab

Debt and Other Obligations (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Schedule of Long-term Debt	Long-term debt is comprised of the following: As of As of September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 (in millions) (weighted-average interest rates) Fixed-rate senior term loans due through 2027 $ 354.7 $ 382.4 4.10 % 4.10 % Fixed-rate junior term loans due through 2022 24.6 31.1 6.90 % 6.90 % Fixed-rate loans due through 2031 660.0 625.1 3.48 % 3.88 % Fixed-rate class A 2015-1 EETC due through 2028 363.6 378.6 4.10 % 4.10 % Fixed-rate class B 2015-1 EETC due through 2024 76.0 80.0 4.45 % 4.45 % Fixed-rate class C 2015-1 EETC due through 2023 103.8 109.5 4.93 % 4.93 % Fixed-rate class AA 2017-1 EETC due through 2030 228.4 242.5 3.38 % 3.38 % Fixed-rate class A 2017-1 EETC due through 2030 76.1 80.8 3.65 % 3.65 % Fixed-rate class B 2017-1 EETC due through 2026 70.6 83.7 3.80 % 3.80 % Fixed-rate class C 2017-1 EETC due through 2023 85.5 85.5 5.11 % 5.11 % Revolving credit facility due in 2020 160.0 135.3 3.45 % 3.72 % Long-term debt 2,203.3 2,234.5 Less current maturities 193.7 162.8 Less unamortized discounts, net 42.0 47.7 Total $ 1,967.6 $ 2,024.0
Schedule of Maturities of Long-term Debt	At September 30, 2019 , long-term debt principal payments for the next five years and thereafter are as follows: September 30, 2019 (in millions) Remainder of 2019 $ 49.3 2020 221.1 2021 280.8 2022 164.3 2023 303.1 2024 and beyond 1,184.7 Total debt principal payments $ 2,203.3
Schedule of Interest Expense, Long-term Debt	Interest expense related to long-term debt and finance leases consists of the following: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (in thousands) Fixed-rate senior term loans $ 3,809 $ 4,195 $ 11,632 $ 12,769 Fixed-rate junior term loans 454 605 1,467 1,908 Fixed-rate term loans 6,517 4,844 19,151 14,636 Class A 2015-1 EETC 3,747 4,057 11,294 12,214 Class B 2015-1 EETC 850 939 2,570 2,881 Class C 2015-1 EETC 1,279 1,420 3,894 2,209 Class AA 2017-1 EETC 1,973 1,751 5,959 4,008 Class A 2017-1 EETC 711 631 2,148 1,445 Class B 2017-1 EETC 708 700 2,199 1,636 Class C 2017-1 EETC 1,104 934 3,275 1,400 Revolving credit facility 1,493 — 4,466 — Amortization of deferred financing costs 2,175 1,784 6,544 4,930 Commitment and other fees 281 49 400 182 Finance leases 37 16 376 54 Total $ 25,138 $ 21,925 $ 75,375 $ 60,272

Recent Accounting Developments

Recent Accounting Developments Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 1,059,766			$ 0
Current maturities of operating leases	117,376			0
Operating leases, less current maturities	$ 915,977			$ 0
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		$ 1,000,000
Current maturities of operating leases		128,100
Operating leases, less current maturities		$ 895,100
Restatement Adjustment [Member] | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets			$ (5,500)

Revenue (Details)

Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Air traffic liability	$ 361,218		$ 361,218		$ 291,981
Total operating revenues	991,968	$ 904,330	2,860,720	$ 2,460,239
DOT—Domestic [Member]
Disaggregation of Revenue [Line Items]
Total operating revenues	880,868	819,323	2,526,016	2,236,334
DOT—Latin America [Member]
Disaggregation of Revenue [Line Items]
Total operating revenues	111,100	85,007	334,704	223,905
Passenger [Member]
Disaggregation of Revenue [Line Items]
Total operating revenues	973,353	887,956	2,805,848	2,413,447
Fare [Member]
Disaggregation of Revenue [Line Items]
Total operating revenues	493,376	476,660	1,425,417	1,258,904
Non Fare [Member]
Disaggregation of Revenue [Line Items]
Total operating revenues	479,977	411,296	1,380,431	1,154,543
Other [Member]
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 18,615	$ 16,374	$ 54,872	$ 46,792

Special Charges (Details)

Special Charges (Details) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018aircraft	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)
Property, Plant and Equipment [Line Items]
Special charges, non-operating	$ 0	$ 1,744			$ 0	$ 90,357
Special Charges [Abstract]
Special charges (credits)	$ 0	$ (686)			$ 0	88,656
Airbus A319 [Member] | Capital Lease Obligations [Member]
Special Charges [Abstract]
Purchase price			$ 285,000
Number of aircrafts purchased | aircraft				14
Pilots [Member]
Special Charges [Abstract]
Ratification Incentive						80,200
Adjustments for contractual provisions						8,500
Special charges (credits)						$ 88,700

Loss on Disposal of Assets (Det

Loss on Disposal of Assets (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)aircraft_engine	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal of assets	$ 13,410	$ 1,069		$ 16,873	$ 6,561
Disposal of excess and obselete inventory			$ 2,200	11,600
Write-down of certain held-for-sale assets to fair value less cost to sell				3,100
Write-down of unrecoverable costs previously capitalized for enterprise accounting software project				2,300
Gain on sale-leaseback transaction				$ 100
Number of aircraft engines sold | aircraft_engine			5
V2500 SelectOne Engine
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of other property, plant, and equipment			$ 9,500
Loss on disposition of assets			$ 4,400

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator
Net income	$ 83,464	$ 114,501	$ 56,076	$ 97,480	$ 11,254	$ (44,922)	$ 254,041	$ 63,812
Denominator
Weighted-average shares outstanding, basic	68,442			68,254			68,421	68,243
Effect of dilutive stock awards	103			249			140	103
Adjusted weighted-average shares outstanding, diluted	68,545			68,503			68,561	68,346
Earnings per share
Basic earnings per common share	$ 1.22			$ 1.43			$ 3.71	$ 0.94
Diluted earnings per common share	$ 1.22			$ 1.42			$ 3.71	$ 0.93
Anti-dilutive weighted-average shares	136			5			141	192

Short-term Investment Securit_2

Short-term Investment Securities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Short-term investment securities	$ 104,792		$ 104,792		$ 102,789
Unrealized gain (loss), net of deferred taxes	(68)	$ (7)	161	$ 70
Tax effect of the unrealized gain (loss) on short-term investment securities	(20)	$ (5)	47	$ 21
Accumulated other comprehensive income (loss)	(875)		$ (875)		(1,193)
Available-for-sale Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Weighted-average fixed rate			2.40%
Accumulated other comprehensive income (loss)	$ 87		$ 87		$ 74

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Salaries and wages	$ 82,572	$ 82,900
Federal excise and other passenger taxes and fees payable	68,716	60,604
Airport obligations	65,351	52,029
Aircraft maintenance	30,113	59,805
Aircraft and facility lease obligations	21,807	15,149
Fuel	21,126	25,368
Interest payable	18,753	18,086
Other	29,247	25,736
Other current liabilities	$ 337,685	$ 339,677

Financial Instruments and Ris_2

Financial Instruments and Risk Management - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Derivative [Line Items]
Interest rate derivative losses reclassified into earnings	$ 57	$ 52	$ 157	$ 172
Loss reclassified from AOCI into earnings, tax	17	27	63	66
Accumulated other comprehensive loss	875		875		$ 1,193
Interest Rate Swap [Member]
Derivative [Line Items]
Accumulated other comprehensive loss	1,000		1,000		$ 1,100
Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Interest rate derivative losses reclassified into earnings	57	52	157	172
Loss reclassified from AOCI into earnings, tax	$ 17	$ 27	$ 63	$ 66

Leases Narrative (Details)

Leases Narrative (Details) $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended
	Jun. 30, 2019USD ($)aircraft	Sep. 30, 2019USD ($)aircraft_engineaircraft	Sep. 30, 2019USD ($)aircraft_engineaircraft	Jan. 01, 2019USD ($)
Lessee, Lease, Description [Line Items]
Operating lease not yet commenced, amount		$ 500	$ 500
Operating lease not yet commenced, amount, year two		0	0
Finance lease obligations		$ 2,231	2,231
Gain on sale-leaseback transaction			100
Airbus A320 [Member]
Lessee, Lease, Description [Line Items]
Interest of lease liabilities, purchased aircraft previously leased			$ 300
Number of aircrafts purchased. previously leased | aircraft		4
Property, plant and equipment, purchase price, aircraft previously leased		$ 141,300
Spare Engines
Lessee, Lease, Description [Line Items]
Number of leased assets financed under operating leases | aircraft_engine		11	11
Aircraft | A320 Family [Member]
Lessee, Lease, Description [Line Items]
Number of leased assets financed under operating leases | aircraft		47	47
Fixed Maintenance Reserve Payments, Aircraft and Related Flight Equipment
Lessee, Lease, Description [Line Items]
Committed expenditures, remainder of 2019		$ 700	$ 700
Committed expenditures, 2020		2,600	2,600
Committed expenditures, 2021		2,600	2,600
Committed expenditures, 2022		2,700	2,700
Committed expenditures, 2023		2,500	2,500
Committed expenditures, 2024 and beyond		$ 500	$ 500
Aircraft
Lessee, Lease, Description [Line Items]
Number of aircraft financed under operating leases with a variable rate | aircraft		1	1
Number of delivered aircraft financed with debt | aircraft			2
Number of previously leased aircraft or engine purchased off lease | aircraft			5
Sale Leaseback Transaction, Number of Spare Aircraft Engines | aircraft			1
Finance lease obligations	$ 94,900
Capital leases, lessee balance sheet, assets by major class, flight equipment, gross	$ 140,500
Aircraft | Minimum
Lessee, Lease, Description [Line Items]
Operating leases, term		8 years	8 years
Aircraft | Maximum
Lessee, Lease, Description [Line Items]
Operating leases, term		18 years	18 years
Spare Engines
Lessee, Lease, Description [Line Items]
Number of previously leased aircraft or engine purchased off lease | aircraft			1
Number of spare engines purchased | aircraft_engine			2
Other Leased Equipment and Property | Maximum
Lessee, Lease, Description [Line Items]
Operating leases, term		30 years	30 years
Leased Computer And Office Equipment | Minimum
Lessee, Lease, Description [Line Items]
Finance leases, term		3 years	3 years
Leased Computer And Office Equipment | Maximum
Lessee, Lease, Description [Line Items]
Finance leases, term		5 years	5 years
Accounting Standards Update 2016-02 | Restatement Adjustment [Member]
Lessee, Lease, Description [Line Items]
Cumulative effect of Topic 842 adjustment				$ (5,500)
Capital Lease Obligations [Member] | Airbus A320 [Member]
Lessee, Lease, Description [Line Items]
Number of aircrafts to be purchased | aircraft	4
Third Party Lessor [Member]
Lessee, Lease, Description [Line Items]
Number of delivered leased aircraft | aircraft			5

Leases Finance and Operating Le

Leases Finance and Operating Lease Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finance Leases
Remainder of 2019	$ 298
2020	780
2021	606
2022	578
2023	202
2024 and thereafter	0
Total minimum lease payments	2,464
Less amount representing interest	233
Present value of minimum lease payments	2,231
Less current portion	814
Long-term portion	1,417
Operating Leases
Less current portion	117,376	$ 0
Long-term portion	915,977	$ 0
Total Operating and Finance Lease Obligations
Remainder of 2019	46,151
2020	179,375
2021	177,157
2022	178,309
2023	159,662
2024 and thereafter	622,253
Total minimum lease payments	1,362,907
Less amount representing interest	327,323
Present value of minimum lease payments	1,035,584
Less current portion	118,190
Long-term portion	917,394
Aircraft and Spare Engine Leases
Operating Leases
Remainder of 2019	45,009
2020	175,661
2021	174,420
2022	176,203
2023	158,328
2024 and thereafter	617,315
Total minimum lease payments	1,346,936
Less amount representing interest	323,560
Present value of minimum lease payments	1,023,376
Less current portion	114,777
Long-term portion	908,599
Property Facility Leases
Operating Leases
Remainder of 2019	699
2020	2,417
2021	2,131
2022	1,528
2023	1,132
2024 and thereafter	4,938
Total minimum lease payments	12,845
Less amount representing interest	3,509
Present value of minimum lease payments	9,336
Less current portion	2,041
Long-term portion	7,295
Other
Operating Leases
Remainder of 2019	145
2020	517
2021	0
2022	0
2023	0
2024 and thereafter	0
Total minimum lease payments	662
Less amount representing interest	21
Present value of minimum lease payments	641
Less current portion	558
Long-term portion	$ 83

Leases Lease Costs (Details)

Leases Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Finance Lease, Cost [Abstract] (Deprecated 2019-01-31)
Amortization of leased assets	$ 135	$ 863
Interest of lease liabilities	302	641
Operating lease cost	39,590	137,943
Short-term lease cost	4,218	11,176
Variable lease cost	29,260	89,030
Total lease cost	$ 73,505	$ 239,653

Leases Weighted Average Lease T

Leases Weighted Average Lease Terms and Discount Rates (Details)	Sep. 30, 2019
Weighted-average remaining lease term
Operating leases	9 years 8 months 12 days
Finance leases	3 years 2 months 12 days
Weighted-average discount rate
Operating leases	6.48%
Finance leases	6.14%

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Aircraft Operating Leases (Details) $ in Millions	Sep. 30, 2019USD ($)aircraft
Long-term Purchase Commitment [Line Items]
Remainder of 2019	9
2020	20
2021	27
Future aircraft to be received	56
Airbus [Member] | A-320-Neo [Member]
Long-term Purchase Commitment [Line Items]
Remainder of 2019	7
2020	15
2021	20
Future aircraft to be received	42
Third Party Lessor [Member] | A320 Family [Member]
Long-term Purchase Commitment [Line Items]
Operating Leases Future Minimum Payments for Aircraft Scheduled for Delivery, Remainder of Fiscal Year | $	$ 0.8
Operating leases Future Minimum Payments for Aircraft, Due in Two Years | $	15
Operating leases Future Minimum Payments for Aircraft, Due in Three Years | $	42
Operating leases Future Minimum Payments for Aircraft, Due in Four Years | $	47.8
Operating leases Future Minimum Payments for Aircraft, Due in Five Years | $	47.8
Operating leases Future Minimum Payments for Aircraft, Due Thereafter | $	$ 420.4
Third Party Lessor [Member] | A-320 [Member]
Long-term Purchase Commitment [Line Items]
Remainder of 2019	2
2020	0
2021	0
Future aircraft to be received	2
Third Party Lessor [Member] | A-320-Neo [Member]
Long-term Purchase Commitment [Line Items]
Remainder of 2019	0
2020	5
2021	7
Future aircraft to be received	12

Commitments and Contingencies_2

Commitments and Contingencies - Aircraft-Related Commitments and Financing Arrangements (Details) $ in Millions	1 Months Ended	36 Months Ended
	Oct. 31, 2019aircraft	Sep. 30, 2022USD ($)	Sep. 30, 2019USD ($)ft²aircraft_engineaircraft
Interest Commitments
Area of Real Estate Property | ft²			500,000
Secured Debt [Member]
Interest Commitments
Interest commitments, remainder of 2019			$ 22.7
Interest commitments, 2020			78.5
Interest commitments, 2021			71.3
Interest commitments, 2022			64.3
Interest commitments, 2023			54.1
Interest commitments, 2024 and beyond			$ 157.9
2019 [Member] | Airbus [Member]
Committed Expenditures
Number of aircraft with secured sale-leaseback financing commitments scheduled for delivery | aircraft			5
2019-2021 [Member] [Member] | Airbus [Member]
Committed Expenditures
Number of aircraft without secured financing commitments scheduled for delivery | aircraft			37
Aircraft and Related Flight Equipment [Member]
Committed Expenditures
Committed expenditures, remainder of 2019			$ 308.1
Committed expenditures, 2020			858.1
Committed expenditures, 2021			776.1
Committed expenditures, 2022			17.6
Committed expenditures, 2023			8.3
Committed expenditures, 2024 and beyond			0
Non-aircraft Related Commitments [Member]
Committed Expenditures
Committed expenditures, remainder of 2019			3.4
Committed expenditures, 2020			17.5
Committed expenditures, 2021			14.7
Committed expenditures, 2022			13.9
Committed expenditures, 2023			12.7
Committed expenditures, 2024 and beyond			$ 60.1
V2500 SelectTWO Engine [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of spare aircraft engines ordered | aircraft_engine			1
PurePower PW1100G-JM Engine [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of spare aircraft engines ordered | aircraft_engine			6
A320 and A321 [Member]
Committed Expenditures
Number of delivered aircraft with secured debt financing commitments | aircraft			62
Forecast [Member] | A320 Family [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircrafts to be purchased | aircraft	100
Number of aircrafts to be purchased, optional | aircraft	50
Forecast [Member] | Real Estate Properties [Domain]
Interest Commitments
Payments to acquire real estate		$ 250

Commitments and Contingencies_3

Commitments and Contingencies - Credit Card Processing Arrangements (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Restricted cash holdbacks	$ 0	$ 0
Maximum Potential Exposure to Cash Holdbacks from Credit Card Processors	$ 399,000,000	$ 321,000,000

Commitments and Contingencies_4

Commitments and Contingencies - Employees (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 28, 2018	Sep. 30, 2019USD ($)employee_group	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)employee_group	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
Special charges (credits)		$ 0	$ (686)	$ 0	$ 88,656
Air Line Pilots Association, International [Member]
Concentration Risk [Line Items]
Term of collective bargaining agreement	5 years
Health Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Accrued health care claims		$ 4,700		$ 4,700		$ 4,400
Pilots [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Ratification Incentive					80,200
Adjustments for contractual provisions					8,500
Special charges (credits)					$ 88,700
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member]
Concentration Risk [Line Items]
Number of union-represented employee groups | employee_group		5		5
Company's employees covered under collective bargaining agreements (as a percent)				80.00%
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member] | Air Line Pilots Association, International [Member]
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)				26.00%
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member] | Association of Flight Attendants [Member]
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)				46.00%
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member] | Professional Airline Flight Control Association [Member]
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)				1.00%
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member] | International Association Of Machinists And Aerospace Workers (IAM) [Member]
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)				3.00%
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member] | Transport Workers Union [Member]
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)				3.00%

Fair Value Measurements - Long-

Fair Value Measurements - Long-term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Carrying Value	$ 2,203.3	$ 2,234.5
Senior Loans [Member]
Debt Instrument [Line Items]
Carrying Value	354.7	382.4
Junior Loans [Member]
Debt Instrument [Line Items]
Carrying Value	24.6	31.1
Fixed Rate Loan [Member]
Debt Instrument [Line Items]
Carrying Value	660	625.1
Equipment Notes, Series A 2015-1 [Member]
Debt Instrument [Line Items]
Carrying Value	363.6	378.6
Equipment Notes, Series B 2015-1 [Member]
Debt Instrument [Line Items]
Carrying Value	76	80
Equipment Notes, Series C 2015-1 [Member]
Debt Instrument [Line Items]
Carrying Value	103.8	109.5
Equipment Notes, Series AA 2017-1 [Member]
Debt Instrument [Line Items]
Carrying Value	228.4	242.5
Equipment Notes, Series A 2017-1 [Member]
Debt Instrument [Line Items]
Carrying Value	76.1	80.8
Equipment Notes, Series B 2017-1 [Member]
Debt Instrument [Line Items]
Carrying Value	70.6	83.7
Equipment Notes, Series C 2017-1 [Member]
Debt Instrument [Line Items]
Carrying Value	85.5	85.5
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Carrying Value	160	135.3
Estimated Fair Value [Member]
Debt Instrument [Line Items]
Estimated Fair Value	2,307.1	2,169.6
Estimated Fair Value [Member] | Level 3 [Member] | Senior Loans [Member]
Debt Instrument [Line Items]
Estimated Fair Value	378	373.6
Estimated Fair Value [Member] | Level 3 [Member] | Junior Loans [Member]
Debt Instrument [Line Items]
Estimated Fair Value	25.3	31.1
Estimated Fair Value [Member] | Level 3 [Member] | Fixed Rate Loan [Member]
Debt Instrument [Line Items]
Estimated Fair Value	699.6	600.1
Estimated Fair Value [Member] | Level 3 [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Estimated Fair Value	160	135.3
Estimated Fair Value [Member] | Level 2 [Member] | Equipment Notes, Series A 2015-1 [Member]
Debt Instrument [Line Items]
Estimated Fair Value	383.6	374.8
Estimated Fair Value [Member] | Level 2 [Member] | Equipment Notes, Series B 2015-1 [Member]
Debt Instrument [Line Items]
Estimated Fair Value	78.8	78.1
Estimated Fair Value [Member] | Level 2 [Member] | Equipment Notes, Series C 2015-1 [Member]
Debt Instrument [Line Items]
Estimated Fair Value	106.4	107.9
Estimated Fair Value [Member] | Level 2 [Member] | Equipment Notes, Series AA 2017-1 [Member]
Debt Instrument [Line Items]
Estimated Fair Value	237.5	228.8
Estimated Fair Value [Member] | Level 2 [Member] | Equipment Notes, Series A 2017-1 [Member]
Debt Instrument [Line Items]
Estimated Fair Value	78.4	76.6
Estimated Fair Value [Member] | Level 2 [Member] | Equipment Notes, Series B 2017-1 [Member]
Debt Instrument [Line Items]
Estimated Fair Value	71.5	79.1
Estimated Fair Value [Member] | Level 2 [Member] | Equipment Notes, Series C 2017-1 [Member]
Debt Instrument [Line Items]
Estimated Fair Value	$ 88	$ 84.2

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 935.7	$ 1,004.7
Short-term investment securities	104.8	102.8
Assets Held-for-sale, Long Lived, Fair Value Disclosure	2.3
Total assets	1,042.8	1,107.5
Total liabilities	0	0
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	935.7	1,004.7
Short-term investment securities	104.8	102.8
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0
Total assets	1,040.5	1,107.5
Total liabilities	0	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Short-term investment securities	0	0
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0
Total assets	0	0
Total liabilities	0	0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Short-term investment securities	0	0
Assets Held-for-sale, Long Lived, Fair Value Disclosure	2.3
Total assets	2.3	0
Total liabilities	$ 0	$ 0

Debt and Other Obligations (Det

Debt and Other Obligations (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)aircraft	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)aircraft	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Future Aircraft To Be Received | aircraft	56		56
Long-term debt	$ 2,203.3		$ 2,203.3		$ 2,234.5
Less current maturities	193.7		193.7		162.8
Less unamortized discounts, net	42		42		47.7
Total	1,967.6		1,967.6		2,024
Repayments of debt obligations	40.1	$ 32.6	125.9	$ 93.2
Senior Loans [Member]
Debt Instrument [Line Items]
Long-term debt	$ 354.7		$ 354.7		$ 382.4
Weighted-average interest rate	4.10%		4.10%		4.10%
Junior Loans [Member]
Debt Instrument [Line Items]
Long-term debt	$ 24.6		$ 24.6		$ 31.1
Weighted-average interest rate	6.90%		6.90%		6.90%
Fixed Rate Loan [Member]
Debt Instrument [Line Items]
Principal amount	$ 70		$ 70
Long-term debt	$ 660		$ 660		$ 625.1
Weighted-average interest rate	3.48%		3.48%		3.88%
Equipment Notes, Series A 2015-1 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 363.6		$ 363.6		$ 378.6
Weighted-average interest rate	4.10%		4.10%		4.10%
Equipment Notes, Series B 2015-1 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 76		$ 76		$ 80
Weighted-average interest rate	4.45%		4.45%		4.45%
Equipment Notes, Series C 2015-1 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 103.8		$ 103.8		$ 109.5
Weighted-average interest rate	4.93%		4.93%		4.93%
Equipment Notes, Series AA 2017-1 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 228.4		$ 228.4		$ 242.5
Weighted-average interest rate	3.38%		3.38%		3.38%
Equipment Notes, Series A 2017-1 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 76.1		$ 76.1		$ 80.8
Weighted-average interest rate	3.65%		3.65%		3.65%
Equipment Notes, Series B 2017-1 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 70.6		$ 70.6		$ 83.7
Weighted-average interest rate	3.80%		3.80%		3.80%
Equipment Notes, Series C 2017-1 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 85.5		$ 85.5		$ 85.5
Weighted-average interest rate	5.11%		5.11%		5.11%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term debt	$ 160		$ 160		$ 135.3
Weighted-average interest rate	3.45%		3.45%		3.72%
Fixed Rate Loan [Member] | Maximum
Debt Instrument [Line Items]
Long-term debt, term	12 years		12 years
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 160		$ 160
Airbus [Member] | Airbus A320 [Member] | Fixed Rate Loan [Member]
Debt Instrument [Line Items]
Number of delivered aircraft financed with debt | aircraft			2
Airbus [Member] | A-320-Neo [Member]
Debt Instrument [Line Items]
Future Aircraft To Be Received | aircraft	42		42
Airbus [Member] | A-320-Neo [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Future Aircraft To Be Received | aircraft	40		40

Debt and Other Obligations - Fu

Debt and Other Obligations - Future Maturities (Details) $ in Millions	Sep. 30, 2019USD ($)
Debt Disclosure [Abstract]
Remainder of 2019	$ 49.3
2020	221.1
2021	280.8
2022	164.3
2023	303.1
2024 and beyond	1,184.7
Total debt principal payments	$ 2,203.3

Debt and Other Obligations - In

Debt and Other Obligations - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Debt Instrument [Line Items]
Amortization of deferred financing costs	$ 2,175	$ 1,784	$ 6,544	$ 4,930
Interest Expense, Other	281	49	400	182
Total	25,138	21,925	75,375	60,272
Senior Loans [Member]
Debt Instrument [Line Items]
Interest expense, term loans	3,809	4,195	11,632	12,769
Junior Loans [Member]
Debt Instrument [Line Items]
Interest expense, term loans	454	605	1,467	1,908
Fixed Rate Loan [Member]
Debt Instrument [Line Items]
Interest expense, term loans	6,517	4,844	19,151	14,636
Equipment Notes, Series A 2015-1 [Member]
Debt Instrument [Line Items]
Interest expense, term loans	3,747	4,057	11,294	12,214
Equipment Notes, Series B 2015-1 [Member]
Debt Instrument [Line Items]
Interest expense, term loans	850	939	2,570	2,881
Equipment Notes, Series C 2015-1 [Member]
Debt Instrument [Line Items]
Interest expense, term loans	1,279	1,420	3,894	2,209
Equipment Notes, Series AA 2017-1 [Member]
Debt Instrument [Line Items]
Interest expense, term loans	1,973	1,751	5,959	4,008
Equipment Notes, Series A 2017-1 [Member]
Debt Instrument [Line Items]
Interest expense, term loans	711	631	2,148	1,445
Equipment Notes, Series B 2017-1 [Member]
Debt Instrument [Line Items]
Interest expense, term loans	708	700	2,199	1,636
Equipment Notes, Series C 2017-1 [Member]
Debt Instrument [Line Items]
Interest expense, term loans	1,104	934	3,275	1,400
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Interest expense, term loans	1,493	0	4,466	0
Finance Lease Obligations [Member]
Debt Instrument [Line Items]
Interest expense, term loans	$ 37	$ 16	$ 376	$ 54