Spirit Airlines (SAVEQ) 10-Q 25 Oct 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Oct. 18, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Entity Registrant Name	SPIRIT AIRLINES, INC.
Entity Central Index Key	1,498,710
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		69,322,496

Condensed Statements Of Operati

Condensed Statements Of Operations (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating revenues:
Passenger	$ 331,004	$ 319,812	$ 900,031	$ 901,851
Non-ticket	290,325	255,029	843,574	719,766
Total operating revenues	621,329	574,841	1,743,605	1,621,617
Operating expenses:
Aircraft fuel	121,844	115,899	321,018	356,232
Salaries, wages and benefits	120,190	95,081	349,530	281,175
Aircraft rent	49,367	53,525	151,433	159,440
Landing fees and other rents	39,345	34,577	114,096	98,487
Distribution	25,565	23,074	73,190	65,920
Maintenance, materials and repairs	30,443	21,473	72,010	61,904
Depreciation and amortization	25,304	19,628	73,370	51,630
Other operating	66,277	54,151	197,833	156,071
Loss on disposal of assets	423	290	1,166	1,300
Special charges (credits)	7,355	(76)	31,609	673
Total operating expenses	486,113	417,622	1,385,255	1,232,832
Operating income	135,216	157,219	358,350	388,785
Other (income) expense:
Interest expense	11,362	5,951	29,588	13,182
Capitalized interest	(3,067)	(3,030)	(9,163)	(8,392)
Interest income	(1,222)	(233)	(4,235)	(544)
Other expense	180	166	407	282
Total other (income) expense	7,253	2,854	16,597	4,528
Income before income taxes	127,963	154,365	341,753	384,257
Provision for income taxes	46,581	57,251	125,367	141,437
Net income	$ 81,382	$ 97,114	$ 216,386	$ 242,820
Basic earnings per share (in dollars per share)	$ 1.17	$ 1.35	$ 3.06	$ 3.35
Diluted earnings per share (in dollars per share)	$ 1.17	$ 1.35	$ 3.05	$ 3.34

Condensed Statements of Compreh

Condensed Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 81,382	$ 97,114	$ 216,386	$ 242,820
Unrealized gain (loss) on interest rate derivative instruments, net of deferred taxes of $0, ($320), $0 and ($511)	0	(553)	0	(909)
Unrealized gain (loss) on investment securities, net of deferred taxes of $3, $0, $3 and $0	4	0	4	0
Interest rate swap losses reclassified into earnings, net of taxes of $32, $15, $97 and $15	56	25	170	25
Other comprehensive income (loss)	60	(528)	174	(884)
Comprehensive income	$ 81,442	$ 96,586	$ 216,560	$ 241,936

Condensed Statements of Compre4

Condensed Statements of Comprehensive Income (Parenthetical) (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Unrealized gain (loss) on interest rate derivative instruments, tax	$ 0	$ (320)	$ 0	$ (511)
Available-for-sale Securities, Income Tax Expense on Change in Unrealized Holding Gain (Loss)	3	0	3	0
Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion, Tax	$ 32	$ 15	$ 97	$ 15

Condensed Balance Sheets (unaud

Condensed Balance Sheets (unaudited) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 825,904	$ 803,632
Investment securities	100,083	0
Accounts receivable, net	35,892	28,266
Aircraft maintenance deposits	87,105	73,415
Prepaid income taxes	6,060	72,278
Prepaid expenses and other current assets	48,455	48,749
Total current assets	1,103,499	1,026,340
Property and equipment:
Flight equipment	1,386,310	834,927
Ground property and equipment	109,451	74,814
Less accumulated depreciation	(105,653)	(65,524)
Total property and equipment	1,390,108	844,217
Deposits on flight equipment purchase contracts	272,690	286,837
Long-term aircraft maintenance deposits	198,426	206,485
Deferred heavy maintenance, net	79,878	89,127
Other long-term assets	85,024	77,539
Total assets	3,129,625	2,530,545
Current liabilities:
Accounts payable	29,906	17,043
Air traffic liability	238,793	216,831
Current maturities of long-term debt	84,443	49,637
Other current liabilities	217,779	182,729
Total current liabilities	570,921	466,240
Long-term debt, less current maturities	894,809	596,693
Long-term deferred income taxes	299,231	221,481
Deferred gains and other long-term liabilities	20,108	20,821
Shareholders’ equity:
Common stock	7	7
Additional paid-in-capital	549,375	544,277
Treasury stock, at cost	(218,572)	(116,182)
Retained earnings	1,015,140	798,754
Accumulated other comprehensive loss	(1,394)	(1,546)
Total shareholders’ equity	1,344,556	1,225,310
Total liabilities and shareholders’ equity	$ 3,129,625	$ 2,530,545

Condensed Statements Of Cash Fl

Condensed Statements Of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities:
Net income	$ 216,386	$ 242,820
Adjustments to reconcile net income to net cash provided by operations:
Unrealized losses on open derivative contracts, net	0	2,239
Losses reclassified from other comprehensive income	267	0
Equity-based compensation	5,503	6,999
Allowance for doubtful accounts	213	7
Amortization of deferred gains and losses	3,837	730
Depreciation and amortization	73,370	51,630
Deferred income tax expense	77,627	63,960
Loss on disposal of assets	1,166	1,300
Lease termination cost	31,609	0
Changes in operating assets and liabilities:
Accounts receivable	(7,840)	(10,374)
Aircraft maintenance deposits	(38,299)	(17,488)
Prepaid income taxes	66,218	0
Long-term deposits and other assets	(43,252)	(44,294)
Accounts payable	(7,044)	2,340
Air traffic liability	21,684	56,960
Other liabilities	38,596	12,161
Net cash provided by operating activities	440,041	368,990
Investing activities:
Proceeds from sale of property and equipment	50	0
Capitalized interest	(7,032)	(2,707)
Pre-delivery deposits for flight equipment, net of refunds	(109,260)	(87,658)
Purchase of investment securities	(100,076)	0
Purchase of property and equipment	(447,455)	(451,799)
Net cash used in investing activities	(663,773)	(542,164)
Financing activities:
Proceeds from issuance of long-term debt	378,569	416,000
Proceeds from stock options exercised	92	32
Payments on debt and capital lease obligations	(29,663)	(16,609)
Proceeds from sale and leaseback transactions	0	7,300
Excess tax benefit (deficiency) from equity-based compensation	(497)	8,818
Repurchase of common stock	(102,390)	(112,162)
Debt issuance costs	(107)	(14,092)
Net cash provided by financing activities	246,004	289,287
Net increase in cash and cash equivalents	22,272	116,113
Cash and cash equivalents at beginning of period	803,632	632,784
Cash and cash equivalents at end of period	825,904	748,897
Cash payments for:
Interest, net of capitalized interest	26,025	3,851
Income taxes paid, net of refunds	$ (18,169)	$ 95,135

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2016
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 that management believes are necessary to fairly present the financial position, results of operations and cash flows of the Company for the respective periods presented. Certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with 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 Annual Report on Form 10-K for the year ended December 31, 2015 filed with the Securities and Exchange Commission on February 17, 2016. 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. The interim results reflected in the unaudited condensed financial statements are not necessarily indicative of the results that may be expected for other interim periods or for the full year. Certain prior period amounts have been reclassified to conform to the current year's presentation.

Recent Accounting Developments

Recent Accounting Developments	9 Months Ended
	Sep. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Developments	Recent Accounting Developments Revenue from Contracts with Customers In May 2014, the Financial Accounting Standards Board (the FASB) issued Accounting Standards Update (ASU) No. 2014-09, (ASU 2014-09), "Revenue from Contracts with Customers." The objective of ASU 2014-09 is to establish a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers. ASU 2014-09 will supersede most of the existing revenue recognition guidance, including industry-specific guidance. The core principle of ASU 2014-09 is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 applies to all contracts with customers except those that are within the scope of other topics in the FASB Accounting Standards Codification. The new guidance is effective for the Company in the first quarter of 2018. Early adoption is permitted, but not before the first quarter of 2017. Entities have the option to use either a full retrospective or modified approach to adopt ASU 2014-09. The Company is currently evaluating the new guidance and has neither determined the full impact this standard may have on its financial statements nor decided upon the planned method of adoption. While the Company is still evaluating the impact, it expects the accounting for its frequent flier program to be impacted as ASU 2014-09 will no longer allow use of the incremental cost method when recording revenue related to the Company's loyalty programs. The Company also expects the classification and timing of recognition of certain ancillary fees to be impacted by adoption of ASU 2014-09. Financial Instruments In January 2016, the FASB issued ASU 2016-01, “Financial Instruments – Overall (Subtopic 825-10).” ASU 2016-01 makes several modifications to Subtopic 825-10 including the elimination of the available-for-sale classification of equity investments, and requires equity investments with readily determinable fair values to be measured at fair value with changes in fair value recognized in net income. ASU 2016-01 is effective for interim and annual periods beginning after December 15, 2017 and is not expected to have a material impact on the Company’s financial statements. Leases In February 2016, the FASB issued ASU No. 2016-02, "Leases (Topic 842)." This standard will require all leases with durations greater than twelve months to be recognized on the balance sheet and is effective for the Company in the first quarter of 2019, with early adoption permitted. The Company is currently evaluating the new guidance and believes adoption of this standard will have a significant impact on its balance sheets although adoption is not expected to significantly change the recognition, measurement or presentation of lease expenses within the statements of operations and cash flows. See Note 8, Commitments and Contingencies for information regarding the Company's undiscounted future lease payments and the timing of those payments. Share-Based Compensation In March 2016, the FASB issued ASU No. 2016-09, "Improvements to Employee Share-Based Payment Accounting," which simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification on the statement of cash flows. The new guidance is effective for the Company in the first quarter of 2017, with early adoption permitted. The Company is in the process of evaluating the impact of adoption of this guidance on its financial statements.

Special Charges

Special Charges	9 Months Ended
	Sep. 30, 2016
Special Charges and Credits [Abstract]
Special Charges	Special Charges During the three months ended September 30, 2016 , the Company purchased three A319 aircraft which were formerly financed under operating lease agreements. The purchase price for the 3 aircraft was $58.8 million , comprised of a cash payment of $58.1 million and the application of security deposits held by the previous lessor of $0.7 million . The Company estimated the fair value of the aircraft to be $38.2 million and has recorded the 3 purchased aircraft within flight equipment on the condensed balance sheets. The Company determined the valuation of the aircraft based on a third-party appraisal considering the condition of each aircraft (a Level 3 measurement). The Company recognized $7.4 million as a cost of terminating the leases within special charges on the condensed statement of operations, made up of the excess of the purchase price paid over the fair value of the aircraft, less previously expensed supplemental rent and other non-cash items of $13.2 million . During the nine months ended September 30, 2016 , the Company purchased six A319 aircraft which were formerly financed under operating lease agreements. The purchase price for the 6 aircraft was $124.7 million , comprised of cash payments of $91.9 million and the application of maintenance and security deposits held by the previous lessors of $32.8 million . The Company estimated the fair value of the aircraft to be $79.4 million and has recorded the 6 purchased aircraft within flight equipment on the condensed balance sheets. The Company determined the valuation of the aircraft based on a third-party appraisal considering the condition of each aircraft (a Level 3 measurement). The Company recognized $31.6 million as a cost of terminating the leases within special charges on the condensed statement of operations, made up of the excess of the purchase price paid over the fair value of the aircraft, less previously expensed supplemental rent and other non-cash items of $13.7 million .

Earnings per Share

Earnings per Share	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share The following table sets forth the computation of basic and diluted earnings per common share: Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 (in thousands, except per share amounts) Numerator Net income $ 81,382 $ 97,114 $ 216,386 $ 242,820 Denominator Weighted-average shares outstanding, basic 69,727 71,738 70,689 72,432 Effect of dilutive stock awards 81 146 143 248 Adjusted weighted-average shares outstanding, diluted 69,808 71,884 70,832 72,680 Net income per share Basic earnings per common share $ 1.17 $ 1.35 $ 3.06 $ 3.35 Diluted earnings per common share $ 1.17 $ 1.35 $ 3.05 $ 3.34 Anti-dilutive weighted-average shares 122 57 87 47

Investment Securities

Investment Securities	9 Months Ended
	Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities The Company's investment securities consist of available-for-sale asset-backed securities with contractual maturities of twelve months or less. These securities are stated at fair value within current assets on the Company's balance sheet. Realized gains and losses on sales of investments, if any, are reflected in nonoperating income (expense) in the statements of operations. Unrealized gains and losses on investment securities are reflected as a component of accumulated other comprehensive income, (AOCI). During the third quarter of 2016, the Company invested $100 million in available-for-sale investment securities, earning interest income at a weighted-average fixed rate of approximately 1.2% . For the three and nine months ended September 30, 2016 , an unrealized gain of $4 thousand , net of deferred taxes of $3 thousand , 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 transacted any sales of these securities.

Accrued Liabilities

Accrued Liabilities	9 Months Ended
	Sep. 30, 2016
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities Other current liabilities as of September 30, 2016 and December 31, 2015 consist of the following: September 30, 2016 December 31, 2015 (in thousands) Salaries and wages $ 45,696 $ 34,123 Federal excise and other passenger taxes and fees payable 41,452 38,254 Aircraft maintenance 39,393 21,688 Airport obligations 36,788 30,849 Interest payable 14,796 12,355 Fuel 11,225 7,084 Aircraft and facility lease obligations 11,117 24,014 Other 17,312 14,362 Other current liabilities $ 217,779 $ 182,729

Financial Instruments and Risk

Financial Instruments and Risk Management	9 Months Ended
	Sep. 30, 2016
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 may use a variety of financial instruments to reduce its exposure to fluctuations in the price of jet fuel and interest rates. The Company does not hold or issue derivative financial instruments for trading purposes. The Company is 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 absolute exposure levels, credit ratings, and historical performance of counterparties relating to derivative 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. Fuel Derivative Instruments The Company's fuel derivative contracts 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 its fuel derivative contracts at fair value and recognizes them in the balance sheet in prepaid expenses and other current assets or other current liabilities. The Company did not enter into any fuel derivative instruments during the three and nine months ended September 30, 2016 . The Company did not elect hedge accounting on any fuel derivative instruments entered into during the three and nine months ended September 30, 2015 and, as a result, changes in the fair value of these fuel derivative contracts are recorded in aircraft fuel expense. During the three and nine months ended September 30, 2016 , the Company did not pay any premiums to acquire jet fuel options. During the three and nine months ended September 30, 2015 , the Company paid $0.3 million and $2.5 million in premiums to acquire jet fuel options, respectively. The following table summarizes the components of aircraft fuel expense for the three and nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 (in thousands) Into-plane fuel cost $ 121,844 $ 114,081 $ 321,018 $ 349,549 Realized losses (gains) related to fuel derivative contracts, net — 1,736 — 8,575 Unrealized losses (gains) related to fuel derivative contracts, net — 82 — (1,892 ) Aircraft fuel $ 121,844 $ 115,899 $ 321,018 $ 356,232 Any premiums and settlements received or paid on fuel derivative contracts are reflected in the accompanying statements of cash flows in net cash provided by operating activities. As of September 30, 2016 and December 31, 2015 , the Company did not have any outstanding fuel derivatives and had no fuel hedging activity for the three and nine months ended September 30, 2016 . Interest Rate Swaps During 2015, the Company settled six forward interest rate swaps that were designed to fix the benchmark interest rate component of interest payments on the debt related to three Airbus A321 aircraft, which the Company took delivery of during the third quarter of 2015. These instruments limited the Company's exposure to changes in the benchmark interest rate in the period from the trade date through the date of maturity. The interest rate swaps were designated as cash flow hedges. The Company 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 accumulated other comprehensive income (AOCI). As of September 30, 2016 and December 31, 2015 , the Company did not have any outstanding interest rate swaps. Realized gains and losses from cash flow hedges are recorded in the statement 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. For the three and nine months ended September 30, 2016 , 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, 2015 , an unrealized loss of $0.6 million and $0.9 million , net of deferred taxes of $0.3 million and $0.5 million , respectively, was recorded within AOCI related to these instruments. For the three and nine months ended September 30, 2016 , the Company reclassified interest rate swap losses of $56 thousand and $170 thousand , net of tax of $32 thousand and $97 thousand , into earnings, respectively. For the three and nine months ended September 30, 2015 , the Company reclassified interest rate swap losses of $25 thousand , net of tax of $15 thousand , into earnings. As of September 30, 2016 and December 31, 2015 , $1.4 million and $1.5 million , net of tax, remained in AOCI related to these instruments.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2016
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, 2016 , the Company's aircraft orders consisted of the following: Airbus Third-Party Lessor A320ceo A320neo A321ceo A320neo Total remainder of 2016 — — 1 5 6 2017 4 — 11 — 15 2018 5 4 5 — 14 2019 1 12 — — 13 2020 — 16 — — 16 2021 — 18 — — 18 10 50 17 5 82 On April 27, 2016 , the Company entered into an amendment to the Airbus A320 Family Purchase Agreement, by and between the Company and Airbus S.A.S., dated May 5, 2004 (Airbus Amendment) which included the conversion of ten Airbus A321neo orders to Airbus A320neo orders. The Company also has four spare engine orders for V2500 SelectOne engines with International Aero Engines (IAE) and nine spare engine orders for PurePower PW1100G-JM engines with Pratt & Whitney. Spare engines are scheduled for delivery from 2016 through 2023 . Purchase commitments for these aircraft and spare engines, including estimated amounts for contractual price escalations and pre-delivery payments, are estimated to be approximately $104 million for the remainder of 2016 , $659 million in 2017 , $650 million in 2018 , $679 million in 2019 , $823 million in 2020 , and $803 million in 2021 and beyond . The Company has secured debt financing commitments of $38.7 million for 1 aircraft scheduled for delivery in the remainder of 2016 and $38.5 million for 1 aircraft scheduled for delivery in 2017. See Note 10, Long-Term Debt - 2015-1 EETCs. In addition, the Company has secured financing for five aircraft to be leased directly from a third party, scheduled for delivery in 2016. The Company does not have financing commitments in place for the remaining 75 Airbus aircraft currently on firm order, which are scheduled for delivery in 2017 through 2021 . Interest commitments related to the secured debt financing of 13 delivered aircraft as of September 30, 2016 are approximately $16.1 million for the remainder of 2016 , $40.6 million in 2017 , $36.8 million in 2018 , $33.3 million in 2019 , $29.7 million in 2020 , and $118.3 million in 2021 and beyond . For principal commitments related to these financed aircraft, refer to Note 10, Long-Term Debt. Principal and interest commitments related to the Company's future secured debt financing of 2 undelivered aircraft as of September 30, 2016 are approximately $1.6 million for the remainder of 2016 , $11.6 million in 2017 , $8.1 million in 2018 , $7.4 million in 2019 , $7.1 million in 2020 , and $65.7 million in 2021 and beyond . As of September 30, 2016 , the Company had a fleet consisting of 89 A320 family aircraft. During the nine months ended September 30, 2016 , the Company took delivery of ten aircraft financed under secured debt arrangements and purchased six previously leased aircraft. For further discussion on the six previously leased aircraft, refer to Note 3, Special Charges. These aircraft are capitalized within flight equipment and generally have depreciable lives of 25 years and estimated residual values of 10% . As of September 30, 2016 , the Company had 55 aircraft and 11 spare engines financed under operating leases with lease term expiration dates ranging from 2017 to 2029 . The Company entered into sale and leaseback transactions with third-party aircraft lessors for the majority of these aircraft and engine leases. Deferred losses resulting from these sale and leaseback transactions are included in other long-term assets on the accompanying balance sheet. Deferred losses are recognized as an increase to rent expense on a straight-line basis over the term of the respective operating leases. Deferred gains are included in deferred credits and other long-term liabilities on the accompanying balance sheet. Deferred gains are recognized as a decrease to rent expense on a straight-line basis over the term of the respective operating leases. 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 supplemental rent expense when it is probable that such amounts will be incurred. 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. Future minimum lease payments under noncancellable operating leases with initial or remaining terms in excess of one year at September 30, 2016 were as follows: Operating Leases Aircraft and Spare Engine Leases Property Facility Leases Total Operating Lease Obligations (in thousands) remainder of 2016 $ 50,986 $ 10,824 $ 61,810 2017 194,607 34,988 229,595 2018 177,717 34,714 212,431 2019 158,818 30,312 189,130 2020 150,842 19,111 169,953 2021 and thereafter 520,857 60,513 581,370 Total minimum lease payments $ 1,253,827 $ 190,462 $ 1,444,289 Aircraft rent expense consists of all minimum lease payments under the terms of the Company's aircraft and spare engine lease agreements recognized on a straight-line basis. Aircraft rent expense also includes supplemental rent. Supplemental rent is made up of maintenance reserves paid or expected to be paid to aircraft lessors in advance of the performance of major maintenance activities that are not probable of being reimbursed and probable return condition obligations. The Company expects supplemental rent to 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. Some of the Company’s master lease agreements provide that the Company pay maintenance reserves to aircraft lessors to be held as collateral in advance of the Company’s required performance of major maintenance activities. Substantially all 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 contractual amounts. Fixed maintenance reserve payments for these aircraft and related flight equipment, including estimated amounts for contractual price escalations, are expected to be $1.8 million for the remainder of 2016 , $6.6 million in 2017 , $5.6 million in 2018 , $4.2 million in 2019 , $3.9 million in 2020 , and $10.2 million in 2021 and beyond . These lease agreements provide that maintenance reserves are reimbursable to the Company upon completion of the maintenance event in an amount equal to either (1) the amount of the maintenance reserves held by the lessor associated with the specific maintenance event or (2) the qualifying costs related to the specific maintenance event. 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, 2016 , the Company was in full compliance with those requirements and does not anticipate having to pay reserves related to these master leases in the future. In July 2015, the Company executed an upgrade service agreement with Airbus Americas Customer Services Inc. (Airbus) to reconfigure the seating and increase capacity in 40 of the Company’s existing A320 aircraft from 178 to 182 seats (reconfiguration). The reconfiguration of the aircraft commenced in the first quarter of 2016 and is expected to be completed during the fourth quarter of 2017. The cost of the reconfiguration is expected to be approximately $0.6 million per aircraft and purchase commitments for the reconfiguration kits are estimated to be approximately $5.0 million for the remainder of 2016, $8.7 million in 2017 and none thereafter . In September 2015, the Company executed a lease agreement with Wayne County Airport Authority (the Authority), which owns and operates Detroit Metropolitan Wayne County Airport (DTW). Under the lease agreement, the Company leases a 10 -acre site, adjacent to the airfield at DTW, in order to construct, operate and maintain an approximately 126,000 -square-foot hangar facility (the project). The project allows for the development of a maintenance hangar in order to fulfill the requirements of the Company's growing fleet and to reduce dependence on third-party facilities and contract line maintenance. The lease agreement has a 30 -year term with 2 10 -year extension options. Upon termination of the lease, ownership will automatically pass to the Authority. The Company estimates it will complete the project during the fourth quarter of 2016 at a cost of approximately $32 million . The Company will depreciate all capitalized costs related to the project over the lesser of the useful life of the asset or the lease term. The Company is contractually obligated to pay the following minimum guaranteed payments for its reservation system, data center and advertising media as of September 30, 2016 : $1.4 million for the remainder of 2016 , $5.2 million in 2017 , $3.8 million in 2018 , $0.2 million in 2019 , $0.2 million in 2020 , and $0.0 million in 2021 and beyond . The Company's current agreement with its reservation system provider expires in 2018. 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 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 if 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, 2016 and December 31, 2015 , 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, 2016 and December 31, 2015 , was $281.4 million and $250.2 million , respectively. Employees The Company has 4 union-represented employee groups that together represented approximately 72% of all employees at September 30, 2016 . The table below sets forth the Company's employee groups and status of the collective bargaining agreements as of September 30, 2016 . Employee Groups Representative Amendable Date Percentage of Workforce Pilots Air Line Pilots Association, International (ALPA) August 2015 26% Flight Attendants Association of Flight Attendants (AFA-CWA) May 2021 42% Dispatchers Transport Workers Union (TWU) August 2018 1% Ramp Service Agents International Association of Machinists and Aerospace Workers (IAMAW) June 2020 3% In March 2016, under the supervision of the National Mediation Board (NMB), the Company and AFA-CWA reached a tentative agreement for a five -year contract with the Company's flight attendants. In May 2016, the flight attendants voted to approve the new five -year contract with the Company. In connection with this agreement, the Company paid a $9.6 million ratification incentive payment to the flight attendants recorded within salaries, wages and benefits in the statement of operations. In August 2015, the Company's collective bargaining agreement with its pilots, represented by ALPA, became amendable. In June 2016, ALPA requested the services of the National Mediation Board (NMB) to facilitate negotiations for an amended agreement and the Company joined ALPA in the request. The NMB has assigned a mediator and the parties continue to meet and work toward a new agreement with the guidance of the mediator. Under the RLA, the parties' current agreement remains in effect until an amended agreement is reached. In July 2014, certain ramp service agents directly employed by the Company voted to be represented by the IAMAW. In May 2015, the Company entered into a five -year interim collective bargaining agreement with the IAMAW, covering material economic terms. In June 2016, the Company and the IAMAW reached an agreement on the remaining terms of the collective bargaining agreement, which is amendable in June 2020 . As of September 30, 2016 , ramp service agents represented by the IAMAW service 1 of the 56 airports where the Company operates. The Company is self-insured for health care 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 $4.6 million and $3.7 million in health care claims as of September 30, 2016 and December 31, 2015 , respectively.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2016
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 does not elect hedge accounting on its fuel derivative instruments. As a result, the Company records the fair value adjustment of its fuel derivatives in the accompanying statement of operations within aircraft fuel and on the balance sheet 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 the 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 derivative instruments executed with the same counterparty under a master netting arrangement. The Company determines fair value of 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 holds. The fair value of the Company's jet fuel swaps is determined based on inputs that are readily available in public markets or can be derived from information available in publicly quoted markets; therefore, the Company 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. Based on the Company's assessment of the valuation model's sensitivity to changes in implied volatility, it concluded that holding other inputs constant, a significant increase (decrease) in implied volatility would result in a significantly higher (lower) fair value measurement for the Company's aircraft fuel derivatives. As of September 30, 2016 and December 31, 2015 , the Company had no outstanding fuel derivatives. Long-Term Debt The estimated fair value of the Company's non-publicly held debt agreements has 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 held debt agreements has been determined to be Level 2, as the Company utilizes quoted market prices to estimate the fair value of its public long-term debt. The carrying amounts and estimated fair values of the Company's long-term debt at September 30, 2016 and December 31, 2015 were as follows: September 30, 2016 December 31, 2015 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Fair value level hierarchy (in millions) Senior long-term debt $ 460.1 $ 477.4 $ 484.2 $ 477.8 Level 3 Junior long-term debt 48.9 50.5 54.3 54.6 Level 3 Class A enhanced equipment trust certificates 394.8 402.7 95.8 94.8 Level 2 Class B enhanced equipment trust certificates 104.5 106.1 25.0 25.2 Level 2 Total long-term debt $ 1,008.3 $ 1,036.7 $ 659.3 $ 652.4 Cash and Cash Equivalents Cash and cash equivalents at September 30, 2016 and December 31, 2015 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. Investment Securities Investment securities at September 30, 2016 are comprised of short-term available-for-sale securities and are categorized as Level 1 instruments, as the Company uses quoted market prices in active markets when determining the fair value of these securities. As of December 31, 2015 , the Company had no outstanding investment securities. Assets and liabilities measured at gross fair value on a recurring basis are summarized below: Fair Value Measurements as of September 30, 2016 Total Level Level Level (in millions) Cash and cash equivalents $ 825.9 $ 825.9 $ — $ — Investment securities $ 100.1 $ 100.1 $ — $ — Total assets $ 926.0 $ 926.0 $ — $ — Total liabilities $ — $ — $ — $ — Fair Value Measurements as of December 31, 2015 Total Level Level Level (in millions) Cash and cash equivalents $ 803.6 $ 803.6 $ — $ — Total assets $ 803.6 $ 803.6 $ — $ — Total liabilities $ — $ — $ — $ — The Company had no transfers of assets or liabilities between any of the above levels during the periods ended September 30, 2016 and December 31, 2015 . The Company's Valuation Group, which reports to the Chief Financial Officer, is made up of individuals from the Company's Treasury and Corporate Accounting departments. The Valuation Group is responsible for the execution of the Company's valuation policies and procedures. The Valuation Group compares the results of the Company's internally developed valuation methods with counterparty reports at each balance sheet date, assesses the Company's valuation methods for accurateness and identifies any needs for modification.

Long-term Debt Long-term Debt

Long-term Debt Long-term Debt	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Long-term Debt	Long-Term Debt As of September 30, 2016 , the Company has issued non-public and public debt instruments. The Company's indebtedness includes the 2014 Framework Agreement, the 2015 Facility Agreements and the 2015-1 EETCs, as defined in the Company's Form 10-K for the year ended December 31, 2015 . 2015-1 EETCs In August 2015, the Company created two separate pass-through trusts, which issued approximately $576.6 million aggregate face amount of Series 2015-1 Class A and Class B enhanced equipment trust certificates (EETCs) in connection with the financing of 15 aircraft. Each class of certificates represents a fractional undivided interest in the respective pass-through trusts and is not an obligation of the Company. The proceeds from the issuance of these certificates are initially held in escrow by a depositary and, upon satisfaction of certain terms and conditions, are released and used to purchase equipment notes which are issued by the Company and secured by the Company's aircraft. As of September 30, 2016 , $499.3 million of the proceeds from the sale of the 2015-1 EETCs had been used to purchase equipment notes in connection with the financing of 3 Airbus A320 aircraft and 10 Airbus A321 aircraft. The remaining two aircraft are scheduled for delivery between November 2016 and January 2017. The Company evaluated whether the pass-through trusts formed are variable interest entities (VIEs) required to be consolidated by the Company under applicable accounting guidance. The Company determined that the pass-through trusts are VIEs and that it does not have a variable interest in the pass-through trusts. Based on this analysis, the Company determined that it is not required to consolidate these pass-through trusts. Long-term debt is comprised of the following: As of Three Months Ended September 30, Nine Months Ended September 30, September 30, 2016 December 31, 2015 2016 2015 2016 2015 (in millions) (weighted-average interest rates) Fixed-rate senior term loans due through 2027 $ 460.1 $ 484.2 4.10 % 4.10 % 4.10 % 4.10 % Fixed-rate junior term loans due through 2022 48.9 54.3 6.90 % 6.90 % 6.90 % 6.90 % Fixed-rate class A enhanced equipment trust certificates due through 2028 394.8 95.8 4.03 % N/A 4.03 % N/A Fixed-rate class B enhanced equipment trust certificates due through 2024 104.5 25.0 4.38 % N/A 4.38 % N/A Long-term debt $ 1,008.3 $ 659.3 Less current maturities 84.4 49.6 Less unamortized discounts, net 29.1 13.0 Total $ 894.8 $ 596.7 During the three and nine months ended September 30, 2016 , the Company made scheduled principal payments of $10.0 million and $29.6 million on its outstanding debt obligations, respectively. During the three and nine months ended September 30, 2015 , the Company made scheduled principal payments of $7.6 million and $15.8 million on its outstanding debt obligations, respectively. At September 30, 2016 , long-term debt principal payments for the next five years and thereafter were as follows: September 30, 2016 (in millions) remainder of 2016 $ 34.7 2017 84.6 2018 80.4 2019 79.1 2020 77.3 2021 and thereafter 652.2 Total debt principal payments $ 1,008.3 Interest Expense Interest expense related to long-term debt consisted of the following: Three Months Ended September 30 Nine Months Ended September 30, 2016 2015 2016 2015 (in thousands) Senior term loans $ 4,917 $ 4,639 $ 14,929 $ 10,260 Junior term loans 879 926 2,721 2,023 Class A enhanced equipment trust certificates 3,538 — 7,419 — Class B enhanced equipment trust certificates 1,015 — 2,124 — Commitment fees 32 — 97 — Amortization of debt discounts 979 340 2,289 729 Total $ 11,360 $ 5,905 $ 29,579 $ 13,012

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2016
Subsequent Events [Abstract]
Subsequent Event	Subsequent Events In October 2016, the Company took delivery of two A320neos, the first US based carrier to take delivery and service such aircraft. These aircraft are financed under operating lease agreements.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2016
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 that management believes are necessary to fairly present the financial position, results of operations and cash flows of the Company for the respective periods presented. Certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with 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 Annual Report on Form 10-K for the year ended December 31, 2015 filed with the Securities and Exchange Commission on February 17, 2016.
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	Revenue from Contracts with Customers In May 2014, the Financial Accounting Standards Board (the FASB) issued Accounting Standards Update (ASU) No. 2014-09, (ASU 2014-09), "Revenue from Contracts with Customers." The objective of ASU 2014-09 is to establish a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers. ASU 2014-09 will supersede most of the existing revenue recognition guidance, including industry-specific guidance. The core principle of ASU 2014-09 is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 applies to all contracts with customers except those that are within the scope of other topics in the FASB Accounting Standards Codification. The new guidance is effective for the Company in the first quarter of 2018. Early adoption is permitted, but not before the first quarter of 2017. Entities have the option to use either a full retrospective or modified approach to adopt ASU 2014-09. The Company is currently evaluating the new guidance and has neither determined the full impact this standard may have on its financial statements nor decided upon the planned method of adoption. While the Company is still evaluating the impact, it expects the accounting for its frequent flier program to be impacted as ASU 2014-09 will no longer allow use of the incremental cost method when recording revenue related to the Company's loyalty programs. The Company also expects the classification and timing of recognition of certain ancillary fees to be impacted by adoption of ASU 2014-09. Financial Instruments In January 2016, the FASB issued ASU 2016-01, “Financial Instruments – Overall (Subtopic 825-10).” ASU 2016-01 makes several modifications to Subtopic 825-10 including the elimination of the available-for-sale classification of equity investments, and requires equity investments with readily determinable fair values to be measured at fair value with changes in fair value recognized in net income. ASU 2016-01 is effective for interim and annual periods beginning after December 15, 2017 and is not expected to have a material impact on the Company’s financial statements. Leases In February 2016, the FASB issued ASU No. 2016-02, "Leases (Topic 842)." This standard will require all leases with durations greater than twelve months to be recognized on the balance sheet and is effective for the Company in the first quarter of 2019, with early adoption permitted. The Company is currently evaluating the new guidance and believes adoption of this standard will have a significant impact on its balance sheets although adoption is not expected to significantly change the recognition, measurement or presentation of lease expenses within the statements of operations and cash flows. See Note 8, Commitments and Contingencies for information regarding the Company's undiscounted future lease payments and the timing of those payments. Share-Based Compensation In March 2016, the FASB issued ASU No. 2016-09, "Improvements to Employee Share-Based Payment Accounting," which simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification on the statement of cash flows. The new guidance is effective for the Company in the first quarter of 2017, with early adoption permitted. The Company is in the process of evaluating the impact of adoption of this guidance on its financial statements.

Earnings per Share (Tables)

Earnings per Share (Tables)	9 Months Ended
	Sep. 30, 2016
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 per common share: Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 (in thousands, except per share amounts) Numerator Net income $ 81,382 $ 97,114 $ 216,386 $ 242,820 Denominator Weighted-average shares outstanding, basic 69,727 71,738 70,689 72,432 Effect of dilutive stock awards 81 146 143 248 Adjusted weighted-average shares outstanding, diluted 69,808 71,884 70,832 72,680 Net income per share Basic earnings per common share $ 1.17 $ 1.35 $ 3.06 $ 3.35 Diluted earnings per common share $ 1.17 $ 1.35 $ 3.05 $ 3.34 Anti-dilutive weighted-average shares 122 57 87 47

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	9 Months Ended
	Sep. 30, 2016
Payables and Accruals [Abstract]
Accrued liabilities included in other current liabilities	Other current liabilities as of September 30, 2016 and December 31, 2015 consist of the following: September 30, 2016 December 31, 2015 (in thousands) Salaries and wages $ 45,696 $ 34,123 Federal excise and other passenger taxes and fees payable 41,452 38,254 Aircraft maintenance 39,393 21,688 Airport obligations 36,788 30,849 Interest payable 14,796 12,355 Fuel 11,225 7,084 Aircraft and facility lease obligations 11,117 24,014 Other 17,312 14,362 Other current liabilities $ 217,779 $ 182,729

Financial Instruments and Ris21

Financial Instruments and Risk Management (Tables)	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Components of aircraft fuel expense	The following table summarizes the components of aircraft fuel expense for the three and nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 (in thousands) Into-plane fuel cost $ 121,844 $ 114,081 $ 321,018 $ 349,549 Realized losses (gains) related to fuel derivative contracts, net — 1,736 — 8,575 Unrealized losses (gains) related to fuel derivative contracts, net — 82 — (1,892 ) Aircraft fuel $ 121,844 $ 115,899 $ 321,018 $ 356,232

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Operating Aircraft Leases	As of September 30, 2016 , the Company's aircraft orders consisted of the following: Airbus Third-Party Lessor A320ceo A320neo A321ceo A320neo Total remainder of 2016 — — 1 5 6 2017 4 — 11 — 15 2018 5 4 5 — 14 2019 1 12 — — 13 2020 — 16 — — 16 2021 — 18 — — 18 10 50 17 5 82
Future minimum lease payments under noncancelable operating leases	Future minimum lease payments under noncancellable operating leases with initial or remaining terms in excess of one year at September 30, 2016 were as follows: Operating Leases Aircraft and Spare Engine Leases Property Facility Leases Total Operating Lease Obligations (in thousands) remainder of 2016 $ 50,986 $ 10,824 $ 61,810 2017 194,607 34,988 229,595 2018 177,717 34,714 212,431 2019 158,818 30,312 189,130 2020 150,842 19,111 169,953 2021 and thereafter 520,857 60,513 581,370 Total minimum lease payments $ 1,253,827 $ 190,462 $ 1,444,289
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, 2016 . Employee Groups Representative Amendable Date Percentage of Workforce Pilots Air Line Pilots Association, International (ALPA) August 2015 26% Flight Attendants Association of Flight Attendants (AFA-CWA) May 2021 42% Dispatchers Transport Workers Union (TWU) August 2018 1% Ramp Service Agents International Association of Machinists and Aerospace Workers (IAMAW) June 2020 3%

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2016
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, 2016 and December 31, 2015 were as follows: September 30, 2016 December 31, 2015 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Fair value level hierarchy (in millions) Senior long-term debt $ 460.1 $ 477.4 $ 484.2 $ 477.8 Level 3 Junior long-term debt 48.9 50.5 54.3 54.6 Level 3 Class A enhanced equipment trust certificates 394.8 402.7 95.8 94.8 Level 2 Class B enhanced equipment trust certificates 104.5 106.1 25.0 25.2 Level 2 Total long-term debt $ 1,008.3 $ 1,036.7 $ 659.3 $ 652.4
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, 2016 Total Level Level Level (in millions) Cash and cash equivalents $ 825.9 $ 825.9 $ — $ — Investment securities $ 100.1 $ 100.1 $ — $ — Total assets $ 926.0 $ 926.0 $ — $ — Total liabilities $ — $ — $ — $ — Fair Value Measurements as of December 31, 2015 Total Level Level Level (in millions) Cash and cash equivalents $ 803.6 $ 803.6 $ — $ — Total assets $ 803.6 $ 803.6 $ — $ — Total liabilities $ — $ — $ — $ —

Long-term Debt (Tables)

Long-term Debt (Tables)	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Schedule of Long-term Debt	Long-term debt is comprised of the following: As of Three Months Ended September 30, Nine Months Ended September 30, September 30, 2016 December 31, 2015 2016 2015 2016 2015 (in millions) (weighted-average interest rates) Fixed-rate senior term loans due through 2027 $ 460.1 $ 484.2 4.10 % 4.10 % 4.10 % 4.10 % Fixed-rate junior term loans due through 2022 48.9 54.3 6.90 % 6.90 % 6.90 % 6.90 % Fixed-rate class A enhanced equipment trust certificates due through 2028 394.8 95.8 4.03 % N/A 4.03 % N/A Fixed-rate class B enhanced equipment trust certificates due through 2024 104.5 25.0 4.38 % N/A 4.38 % N/A Long-term debt $ 1,008.3 $ 659.3 Less current maturities 84.4 49.6 Less unamortized discounts, net 29.1 13.0 Total $ 894.8 $ 596.7
Schedule of Maturities of Long-term Debt	At September 30, 2016 , long-term debt principal payments for the next five years and thereafter were as follows: September 30, 2016 (in millions) remainder of 2016 $ 34.7 2017 84.6 2018 80.4 2019 79.1 2020 77.3 2021 and thereafter 652.2 Total debt principal payments $ 1,008.3
Schedule of Interest Expense, Long-term Debt	Interest expense related to long-term debt consisted of the following: Three Months Ended September 30 Nine Months Ended September 30, 2016 2015 2016 2015 (in thousands) Senior term loans $ 4,917 $ 4,639 $ 14,929 $ 10,260 Junior term loans 879 926 2,721 2,023 Class A enhanced equipment trust certificates 3,538 — 7,419 — Class B enhanced equipment trust certificates 1,015 — 2,124 — Commitment fees 32 — 97 — Amortization of debt discounts 979 340 2,289 729 Total $ 11,360 $ 5,905 $ 29,579 $ 13,012

Special Charges (Details)

Special Charges (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016USD ($)aircraft	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)aircraft	Sep. 30, 2015USD ($)
Property, Plant and Equipment [Line Items]
Payments for Purchase of Other Assets			$ 447,455	$ 451,799
Special charges (credits)	$ 7,355	$ (76)	$ 31,609	$ 673
Aircraft [Member]
Property, Plant and Equipment [Line Items]
Number of Previously Leased Aircraft Purchased | aircraft			6
Airbus A319 [Member] | Aircraft [Member]
Property, Plant and Equipment [Line Items]
Number of Previously Leased Aircraft Purchased | aircraft	3		6
Payments to Acquire Equipment on Lease	$ 58,800		$ 124,700
Payments for Purchase of Other Assets	58,100		91,900
Noncash or Part Noncash Acquisition, Description	700		32,800
Fair Value of Assets Acquired	38,200		79,400
Special charges (credits)	7,355		31,648
Operating Leases, Rent Expense, Supplemental, Maintenance Reserves	$ 13,200		$ 13,700

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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Numerator
Net income	$ 81,382	$ 97,114	$ 216,386	$ 242,820
Denominator
Weighted-average shares outstanding, basic (in shares)	69,727	71,738	70,689	72,432
Effect of dilutive stock awards (in shares)	81	146	143	248
Adjusted weighted-average shares outstanding, diluted (in shares)	69,808	71,884	70,832	72,680
Net income per share
Basic earnings per common share (in dollars per share)	$ 1.17	$ 1.35	$ 3.06	$ 3.35
Diluted earnings per common share (in dollars per share)	$ 1.17	$ 1.35	$ 3.05	$ 3.34
Anti-dilutive weighted-average shares	122	57	87	47

Investment Securities (Details)

Investment Securities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Investment securities	$ 100,083		$ 100,083		$ 0
Weighted-average fixed rate	1.20%
Unrealized gain on investment securities, net of deferred taxes	$ 4	$ 0	4	$ 0
Deferred taxes on unrealized gain on investment securities	$ 3	$ 0	$ 3	$ 0

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Salaries and wages	$ 45,696	$ 34,123
Salaries and wages	41,452	38,254
Aircraft maintenance	36,788	30,849
Interest payable	39,393	21,688
Fuel	14,796	12,355
Aircraft and facility lease obligations	11,225	7,084
Airport obligations	11,117	24,014
Other	17,312	14,362
Other current liabilities	$ 217,779	$ 182,729

Financial Instruments and Ris29

Financial Instruments and Risk Management (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Into-plane fuel cost	$ 121,844	$ 114,081	$ 321,018	$ 349,549
Realized losses (gains) related to fuel derivative contracts, net	0	1,736	0	8,575
Unrealized losses (gains) related to fuel derivative contracts, net	0	82	0	(1,892)
Aircraft fuel	$ 121,844	$ 115,899	$ 321,018	$ 356,232

Financial Instruments and Ris30

Financial Instruments and Risk Management - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)aircraftderivative_instrument
Derivative [Line Items]
Unrealized loss on interest rate derivative instruments	$ 0	$ 553	$ 0	$ 909
Unrealized gain (loss) on interest rate derivative instruments, tax	0	(320)	0	(511)
Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion, Tax	32	15	97	15
Accumulated other comprehensive loss	(1,394)		(1,394)		$ (1,546)
Airbus A321 [Member] | 2015 [Member]
Derivative [Line Items]
Number of aircraft protected by interest rate derivatives schedule for delivery | aircraft					3
Commodity Option [Member]
Derivative [Line Items]
Payments for Premiums on Fuel Option Derivatives		300		2,500
Interest Rate Swap [Member]
Derivative [Line Items]
Number of interest rate derivatives settled | derivative_instrument					6
Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Unrealized loss on interest rate derivative instruments		600		900
Unrealized gain (loss) on interest rate derivative instruments, tax		300		500
Loss reclassified from AOCI into earnings	56	25	170	25
Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion, Tax	$ 32	$ 15	$ 97	$ 15

Commitments and Contingencies -

Commitments and Contingencies - Aircraft Contractual Purchase Commitments (Details)	Sep. 30, 2016aircraft
Long-term Purchase Commitment [Line Items]
Future Aircraft To Be Received, Remainder of Fiscal Year	6
Future Aircraft To Be Received, in Two Years	15
Future Aircraft To Be Received, in Three Years	14
Future Aircraft To Be Received, in Four Years	13
Future Aircraft To Be Received, in Five Years	16
Future Aircraft To Be Received, in Six Years	18
Future Aircraft To Be Received	82
Airbus [Member] | A320 [Member]
Long-term Purchase Commitment [Line Items]
Future Aircraft To Be Received, Remainder of Fiscal Year	0
Future Aircraft To Be Received, in Two Years	4
Future Aircraft To Be Received, in Three Years	5
Future Aircraft To Be Received, in Four Years	1
Future Aircraft To Be Received, in Five Years	0
Future Aircraft To Be Received, in Six Years	0
Future Aircraft To Be Received	10
Airbus [Member] | A-320-Neo [Member]
Long-term Purchase Commitment [Line Items]
Future Aircraft To Be Received, Remainder of Fiscal Year	0
Future Aircraft To Be Received, in Two Years	0
Future Aircraft To Be Received, in Three Years	4
Future Aircraft To Be Received, in Four Years	12
Future Aircraft To Be Received, in Five Years	16
Future Aircraft To Be Received, in Six Years	18
Future Aircraft To Be Received	50
Airbus [Member] | A321 [Member]
Long-term Purchase Commitment [Line Items]
Future Aircraft To Be Received, Remainder of Fiscal Year	1
Future Aircraft To Be Received, in Two Years	11
Future Aircraft To Be Received, in Three Years	5
Future Aircraft To Be Received, in Four Years	0
Future Aircraft To Be Received, in Five Years	0
Future Aircraft To Be Received, in Six Years	0
Future Aircraft To Be Received	17
Third Party Lessor [Member] | A-320-Neo [Member]
Long-term Purchase Commitment [Line Items]
Future Aircraft To Be Received, Remainder of Fiscal Year	5
Future Aircraft To Be Received, in Two Years	0
Future Aircraft To Be Received, in Three Years	0
Future Aircraft To Be Received, in Four Years	0
Future Aircraft To Be Received, in Five Years	0
Future Aircraft To Be Received, in Six Years	0
Future Aircraft To Be Received	5

Commitments and Contingencies32

Commitments and Contingencies - Aircraft Contractual Purchase Commitments Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)aircraft_engineaircraft	Apr. 27, 2016aircraft	Aug. 31, 2015USD ($)
A320 Family [Member]
Long-term Purchase Commitment [Line Items]
Number of aircraft held	89
Airbus [Member] | A320 and A321 [Member]
Long-term Purchase Commitment [Line Items]
Number of aircraft order conversions		10
Number of aircraft with secured debt financing commitments scheduled for delivery	2
Number of delivered aircraft with secured debt financing commitments	13
V2500 SelectOne Engine [Member]
Long-term Purchase Commitment [Line Items]
Number of spare aircraft engines ordered (in aircraft engine) | aircraft_engine	4
PurePower PW1100G-JM Engine [Member]
Long-term Purchase Commitment [Line Items]
Number of spare aircraft engines ordered (in aircraft engine) | aircraft_engine	9
Capital Addition Purchase Commitments [Member]
Long-term Purchase Commitment [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year | $	$ 104
Unrecorded Unconditional Purchase Obligation, Due in 2017 | $	659
Unrecorded Unconditional Purchase Obligation, Due in 2018 | $	650
Unrecorded Unconditional Purchase Obligation, Due in 2019 | $	679
Unrecorded Unconditional Purchase Obligation, Due in 2020 | $	823
Unrecorded Unconditional Purchase Obligation, Due in 2021 and beyond | $	$ 803
2016 [Member]
Long-term Purchase Commitment [Line Items]
Number of aircraft with secured debt financing commitments scheduled for delivery	1
2016 [Member] | Third Party Lessor [Member]
Long-term Purchase Commitment [Line Items]
Number of Direct Leased Aircraft Ordered From A Third Party	5
2017 [Member]
Long-term Purchase Commitment [Line Items]
Number of aircraft with secured debt financing commitments scheduled for delivery	1
2017-2021 [Member] | Airbus [Member]
Long-term Purchase Commitment [Line Items]
Number of Aircraft without Secured Financing Commitments Scheduled for Delivery	75
Enhanced Equipment Trust Certificate [Member] | Capital Addition Purchase Commitments [Member]
Long-term Purchase Commitment [Line Items]
Debt financing commitments | $			$ 576.6
Enhanced Equipment Trust Certificate [Member] | 2016 [Member] | Capital Addition Purchase Commitments [Member]
Long-term Purchase Commitment [Line Items]
Debt financing commitments | $	$ 38.7
Enhanced Equipment Trust Certificate [Member] | 2017 [Member] | Capital Addition Purchase Commitments [Member]
Long-term Purchase Commitment [Line Items]
Debt financing commitments | $	$ 38.5
Aircraft [Member]
Long-term Purchase Commitment [Line Items]
Number of delivered aircraft with secured debt financing commitments	10
Number of Previously Leased Aircraft Purchased	6
Property and equipment, useful life	25 years
Property and equipment, salvage value percentage	10.00%
Spare Engines [Member]
Long-term Purchase Commitment [Line Items]
Operating leases, lessee, number of leased assets | aircraft_engine	11
Aircraft [Member]
Long-term Purchase Commitment [Line Items]
Operating leases, lessee, number of leased assets	55

Commitments and Contingencies33

Commitments and Contingencies - Long Term Debt Commitments (Details) - Secured Debt [Member] $ in Millions	Sep. 30, 2016USD ($)
Debt Instrument [Line Items]
Repayments of interest and fee commitments, remainder of 2016	$ 16.1
Repayments of interest and fee commitments, in 2017	40.6
Repayments of interest and fee commitments, in 2018	36.8
Repayments of interest and fee commitments, in 2019	33.3
Repayments of interest and fee commitments, in 2020	29.7
Repayments of interest and fee commitments, 2021 and beyond	118.3
Long-term Debt, Fiscal Year Maturity [Abstract]
Remainder of 2016	1.6
2,017	11.6
2,018	8.1
2,019	7.4
2,020	7.1
2021 and beyond	$ 65.7

Commitments and Contingencies34

Commitments and Contingencies - Future Minimum Lease Payments Under Noncancelable Operating Leases (Details) $ in Thousands	Sep. 30, 2016USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
remainder of 2016	$ 61,810
Future Minimum Payments Due, 2017	229,595
Future Minimum Payments Due, 2018	212,431
Future Minimum Payments Due, 2019	189,130
Future Minimum Payments Due, 2020	169,953
Future Minimum Payments Due, 2021 and thereafter	581,370
Total minimum lease payments	1,444,289
Aircraft and Spare Engine Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
remainder of 2016	50,986
Future Minimum Payments Due, 2017	194,607
Future Minimum Payments Due, 2018	177,717
Future Minimum Payments Due, 2019	158,818
Future Minimum Payments Due, 2020	150,842
Future Minimum Payments Due, 2021 and thereafter	520,857
Total minimum lease payments	1,253,827
Property Facility Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
remainder of 2016	10,824
Future Minimum Payments Due, 2017	34,988
Future Minimum Payments Due, 2018	34,714
Future Minimum Payments Due, 2019	30,312
Future Minimum Payments Due, 2020	19,111
Future Minimum Payments Due, 2021 and thereafter	60,513
Total minimum lease payments	$ 190,462

Commitments and Contingencies35

Commitments and Contingencies - Fixed Maintenance Reserve Payments and Other Commitments (Details) $ in Millions	Sep. 30, 2016USD ($)
Fixed Maintenance Reserve Payments, Aircraft and Related Flight Equipment [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year	$ 1.8
Unrecorded Unconditional Purchase Obligation, Due in 2017	6.6
Unrecorded Unconditional Purchase Obligation, Due in 2018	5.6
Unrecorded Unconditional Purchase Obligation, Due in 2019	4.2
Unrecorded Unconditional Purchase Obligation, Due in 2020	3.9
Unrecorded Unconditional Purchase Obligation, Due in 2021 and beyond	10.2
Reservation System and Advertising Media [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year	1.4
Unrecorded Unconditional Purchase Obligation, Due in 2017	5.2
Unrecorded Unconditional Purchase Obligation, Due in 2018	3.8
Unrecorded Unconditional Purchase Obligation, Due in 2019	0.2
Unrecorded Unconditional Purchase Obligation, Due in 2020	0.2
Unrecorded Unconditional Purchase Obligation, Due in 2021 and beyond	0
Airbus [Member] | Aircraft with Increased Seating Capacity [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year	5
Unrecorded Unconditional Purchase Obligation, Due in 2017	8.7
Unrecorded Unconditional Purchase Obligation, Due after Two Years	$ 0

Commitments and Contingencies36

Commitments and Contingencies - Commitments (Details) ft² in Thousands, $ in Millions	1 Months Ended
	Sep. 30, 2015ft²aextension_option	Jul. 31, 2015USD ($)aircraftseat	Sep. 30, 2016USD ($)
Hangar Facility [Member] | Operating Lease [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Area of land, hangar site | a	10
Area of hangar facility | ft²	126
Operating lease, initial term	30 years
Operating lease, number of extension options | extension_option	2
Operating lease, extension term	10 years
Estimated future project costs | $			$ 32
Airbus [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Costs to reconfigure aircraft seating | $		$ 0.6
Airbus [Member] | A320 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircraft reconfigured for increased seating capacity | aircraft		40
Airbus [Member] | A320 [Member] | Minimum [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircraft seats | seat		178
Airbus [Member] | A320 [Member] | Maximum [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircraft seats | seat		182

Commitments and Contingencies37

Commitments and Contingencies - Credit Card Processing Arrangements (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Restricted cash holdbacks	$ 0	$ 0
Maximum Potential Exposure to Cash Holdbacks from Credit Card Processors	$ 281,400,000	$ 250,200,000

Commitments and Contingencies38

Commitments and Contingencies - Employees (Details) $ in Millions	Mar. 31, 2016	May 31, 2016	May 31, 2015	Sep. 30, 2016USD ($)airport	Jun. 30, 2016USD ($)	Sep. 30, 2016USD ($)airport	Dec. 31, 2015USD ($)
Concentration Risk [Line Items]
Number of airports in which entity operates | airport				56		56
Association of Flight Attendants [Member]
Concentration Risk [Line Items]
Tentative collective bargaining agreement, contract term	5 years
Compensation | $					$ 9.6
Ratified Collective Bargaining Agreement, Contract Term		5 years
International Association Of Machinists And Aerospace Workers (IAM) [Member]
Concentration Risk [Line Items]
Tentative collective bargaining agreement, contract term			5 years
Number of airports in which entity operates | airport				1		1
Health Insurance [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Accrued health care claims | $				$ 4.6		$ 4.6	$ 3.7
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member]
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)						72.00%
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)				42.00%
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)				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%

Fair Value Measurements - Long-

Fair Value Measurements - Long-term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Carrying Value	$ 1,008.3	$ 659.3
Senior Loans [Member]
Debt Instrument [Line Items]
Carrying Value	460.1	484.2
Junior Loans [Member]
Debt Instrument [Line Items]
Carrying Value	48.9	54.3
Equipment Notes, Series A [Member]
Debt Instrument [Line Items]
Carrying Value	394.8	95.8
Equipment Notes, Series B [Member]
Debt Instrument [Line Items]
Carrying Value	104.5	25
Estimated Fair Value [Member]
Debt Instrument [Line Items]
Estimated Fair Value	1,036.7	652.4
Estimated Fair Value [Member] | Level 3 [Member] | Senior Loans [Member]
Debt Instrument [Line Items]
Estimated Fair Value	477.4	477.8
Estimated Fair Value [Member] | Level 3 [Member] | Junior Loans [Member]
Debt Instrument [Line Items]
Estimated Fair Value	50.5	54.6
Estimated Fair Value [Member] | Level 2 [Member] | Equipment Notes, Series A [Member]
Debt Instrument [Line Items]
Estimated Fair Value	402.7	94.8
Estimated Fair Value [Member] | Level 2 [Member] | Equipment Notes, Series B [Member]
Debt Instrument [Line Items]
Estimated Fair Value	$ 106.1	$ 25.2

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 825,904	$ 803,600
Investment securities	100,083
Total assets	925,987	803,600
Total liabilities	0	0
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	825,904	803,600
Investment securities	100,083
Total assets	925,987	803,600
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
Investment securities	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
Investment securities	0
Total assets	0	0
Total liabilities	$ 0	$ 0

Long-term Debt (Details)

Long-term Debt (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 1,008,300		$ 1,008,300		$ 659,300
Less current maturities	84,443		84,443		49,637
Less unamortized discounts, net	29,100		29,100		13,000
Long-term debt, less current maturities	894,809		894,809		596,693
Repayments of debt obligations	10,000	$ 7,600	29,600	$ 15,800
Senior Loans [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 460,100		$ 460,100		484,200
Long-term Debt, Weighted Average Interest Rate	4.10%	4.10%	4.10%	4.10%
Junior Loans [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 48,900		$ 48,900		54,300
Long-term Debt, Weighted Average Interest Rate	6.90%	6.90%	6.90%	6.90%
Equipment Notes, Series A [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 394,800		$ 394,800		95,800
Long-term Debt, Weighted Average Interest Rate	4.03%		4.03%
Equipment Notes, Series B [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 104,500		$ 104,500		$ 25,000
Long-term Debt, Weighted Average Interest Rate	4.38%		4.38%

Long-term Debt - Future Maturit

Long-term Debt - Future Maturities (Details) $ in Millions	Sep. 30, 2016USD ($)
Debt Disclosure [Abstract]
remainder of 2016	$ 34.7
2,017	84.6
2,018	80.4
2,019	79.1
2,020	77.3
2021 and thereafter	652.2
Total debt principal payments	$ 1,008.3

Long-term Debt - EETCs (Details

Long-term Debt - EETCs (Details) $ in Millions	1 Months Ended
	Aug. 31, 2015USD ($)aircrafttrust	Sep. 30, 2016USD ($)aircraft
Airbus [Member] | A320 and A321 [Member]
Debt Instrument [Line Items]
Number of aircraft with secured debt financing commitments scheduled for delivery		2
Number of delivered aircraft with secured debt financing commitments		13
Enhanced Equipment Trust Certificate [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount | $		$ 499.3
Enhanced Equipment Trust Certificate [Member] | Capital Addition Purchase Commitments [Member]
Debt Instrument [Line Items]
Number of pass-through trusts | trust	2
Debt financing commitments | $	$ 576.6
Enhanced Equipment Trust Certificate [Member] | Airbus [Member] | A320 and A321 [Member]
Debt Instrument [Line Items]
Number of aircraft with secured debt financing commitments scheduled for delivery	15
Enhanced Equipment Trust Certificate [Member] | Airbus [Member] | A320 [Member]
Debt Instrument [Line Items]
Number of delivered aircraft with secured debt financing commitments		3
Enhanced Equipment Trust Certificate [Member] | Airbus [Member] | A321 [Member]
Debt Instrument [Line Items]
Number of aircraft with secured debt financing commitments scheduled for delivery		2
Number of delivered aircraft with secured debt financing commitments		10

Long-term Debt - Interest Expen

Long-term Debt - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Commitment fees	$ 32	$ 0	$ 97	$ 0
Amortization of debt discounts	979	340	2,289	729
Total	11,360	5,905	29,579	13,012
Senior Loans [Member]
Debt Instrument [Line Items]
Interest expense, term loans	4,917	4,639	14,929	10,260
Junior Loans [Member]
Debt Instrument [Line Items]
Interest expense, term loans	879	926	2,721	2,023
Equipment Notes, Series A [Member]
Debt Instrument [Line Items]
Interest expense, term loans	3,538	0	7,419	0
Equipment Notes, Series B [Member]
Debt Instrument [Line Items]
Interest expense, term loans	$ 1,015	$ 0	$ 2,124	$ 0

Subsequent Event (Details)

Subsequent Event (Details)	1 Months Ended
	Oct. 25, 2016aircraft
Subsequent Event [Member] | Airbus [Member] | A-320-Neo [Member]
Subsequent Event [Line Items]
Number of Aircrafts Delivered	2