Spirit Airlines (SAVEQ) 10-Q 27 Jul 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 20, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
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		69,369,045

Condensed Statements Of Operati

Condensed Statements Of Operations (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Operating revenues:
Passenger	$ 371,922	$ 296,401	$ 671,684	$ 569,027
Non-ticket	329,760	287,732	621,744	553,249
Total operating revenues	701,682	584,133	1,293,428	1,122,276
Operating expenses:
Salaries, wages and benefits	129,892	112,930	257,030	229,340
Aircraft fuel	142,294	113,192	282,076	199,174
Aircraft rent	52,566	49,864	109,636	102,066
Landing fees and other rents	45,592	39,944	86,040	74,751
Depreciation and amortization	35,331	24,957	66,840	48,066
Maintenance, materials and repairs	28,985	20,627	55,297	41,567
Distribution	29,908	24,692	56,406	47,625
Special charges	0	8,052	4,776	24,254
Loss on disposal of assets	1,493	529	2,598	743
Other operating	102,885	67,511	180,588	131,556
Total operating expenses	568,946	462,298	1,101,287	899,142
Operating income	132,736	121,835	192,141	223,134
Other (income) expense:
Interest expense	13,746	10,166	26,219	18,226
Capitalized interest	(3,342)	(2,771)	(6,922)	(6,096)
Interest income	(1,828)	(1,447)	(3,141)	(3,013)
Other expense	104	157	107	227
Total other (income) expense	8,680	6,105	16,263	9,344
Income before income taxes	124,056	115,730	175,878	213,790
Provision for income taxes	45,913	42,646	65,800	78,786
Net income	$ 78,143	$ 73,084	$ 110,078	$ 135,004
Basic earnings per share (in dollars per share)	$ 1.13	$ 1.03	$ 1.59	$ 1.90
Diluted earnings per share (in dollars per share)	$ 1.12	$ 1.03	$ 1.58	$ 1.89

Condensed Statements of Compreh

Condensed Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 78,143	$ 73,084	$ 110,078	$ 135,004
Unrealized gain (loss) on short-term investment securities, net of deferred taxes of ($6), $0, ($14) and $0	(11)	0	(24)	0
Interest rate derivative losses reclassified into earnings, net of taxes of $31, $32, $62 and $65	53	56	107	113
Other comprehensive income (loss)	42	56	83	113
Comprehensive income	$ 78,185	$ 73,140	$ 110,161	$ 135,117

Condensed Statements of Compre4

Condensed Statements of Comprehensive Income (Parenthetical) (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Tax effect of the unrealized gain (loss) on short-term investment securities	$ 6	$ 0	$ 14	$ 0
Loss reclassified from AOCI into earnings, tax	$ 31	$ 32	$ 62	$ 65

Condensed Balance Sheets (unaud

Condensed Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 869,153	$ 700,900
Short-term investment securities	100,464	100,155
Accounts receivable, net	47,996	41,136
Aircraft maintenance deposits	155,093	87,035
Prepaid expenses and other current assets	57,798	46,619
Total current assets	1,230,504	975,845
Property and equipment:
Flight equipment	1,809,747	1,461,525
Ground property and equipment	140,954	126,206
Less accumulated depreciation	(161,191)	(122,509)
Total property and equipment	1,789,510	1,465,222
Deposits on flight equipment purchase contracts	317,867	325,688
Long-term aircraft maintenance deposits	146,162	199,415
Deferred heavy maintenance, net	75,858	75,534
Other long-term assets	114,444	110,223
Total assets	3,674,345	3,151,927
Current liabilities:
Accounts payable	33,186	15,193
Air traffic liability	312,587	206,392
Current maturities of long-term debt	95,428	84,354
Other current liabilities	244,629	226,011
Total current liabilities	685,830	531,950
Long-term debt, less current maturities	1,089,159	897,359
Deferred income taxes	372,998	308,143
Deferred gains and other long-term liabilities	18,125	19,868
Shareholders’ equity:
Common stock	7	7
Additional paid-in-capital	555,704	551,004
Treasury stock, at cost	(219,909)	(218,692)
Retained earnings	1,173,711	1,063,633
Accumulated other comprehensive loss	(1,280)	(1,345)
Total shareholders’ equity	1,508,233	1,394,607
Total liabilities and shareholders’ equity	$ 3,674,345	$ 3,151,927

Condensed Statements Of Cash Fl

Condensed Statements Of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Operating activities:
Net income	$ 110,078	$ 135,004
Adjustments to reconcile net income to net cash provided by operations:
Losses reclassified from other comprehensive income	167	178
Equity-based compensation	4,671	3,905
Allowance for doubtful accounts (recoveries)	(51)	221
Amortization of deferred gains and losses and debt issuance costs	4,761	2,810
Depreciation and amortization	66,840	48,066
Deferred income tax expense	64,789	45,810
Loss on disposal of assets	2,598	743
Lease termination costs	4,776	24,254
Changes in operating assets and liabilities:
Accounts receivable	(6,808)	(12,662)
Aircraft maintenance deposits	(17,940)	(29,721)
Prepaid income taxes	(1,598)	69,444
Long-term deposits and other assets	(44,900)	(22,055)
Accounts payable	16,388	3,024
Air traffic liability	105,486	66,531
Other liabilities	14,234	25,269
Other	239	0
Net cash provided by operating activities	323,730	360,821
Investing activities:
Purchase of available-for-sale investment securities	(68,459)	0
Proceeds from the maturity of available-for-sale investment securities	67,857	0
Proceeds from sale of property and equipment	0	50
Pre-delivery deposits for flight equipment, net of refunds	(79,357)	(60,772)
Capitalized interest	(6,375)	(4,554)
Purchase of property and equipment	(269,519)	(303,175)
Net cash used in investing activities	(355,853)	(368,451)
Financing activities:
Proceeds from issuance of long-term debt	255,827	300,547
Proceeds from stock options exercised	29	92
Payments on debt and capital lease obligations	(50,099)	(19,665)
Excess tax (deficiency) benefit from equity-based compensation	0	(511)
Repurchase of common stock	(1,217)	(62,278)
Debt issuance costs	(4,164)	(107)
Net cash provided by financing activities	200,376	218,078
Net (decrease) increase in cash and cash equivalents	168,253	210,448
Cash and cash equivalents at beginning of period	700,900	803,632
Cash and cash equivalents at end of period	869,153	1,014,080
Cash payments for:
Interest, net of capitalized interest	16,869	21,804
Income taxes paid, net of refunds	4,340	(36,142)
Non-cash transactions:
Capital expenditures funded by capital lease borrowings	$ (1,370)	$ (31)

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2017
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 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, 2016 filed with the Securities and Exchange Commission on February 13, 2017. 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.

Recent Accounting Developments

Recent Accounting Developments	6 Months Ended
	Jun. 30, 2017
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. The new guidance is effective for the Company in the first quarter of 2018. Entities have the option to use either a full retrospective or a modified retrospective approach to adopt ASU 2014-09. The Company currently anticipates utilizing the full retrospective method of adoption allowed by the standard, in order to provide for comparative results in all periods presented, and plans to adopt the standard as of January 1, 2018. While the Company is still evaluating the impact, it currently believes the most significant impact of this ASU will be the elimination of the incremental cost method for frequent flier program accounting, which will require the Company to re-value and record a liability associated with customer flight miles earned as part of the Company’s frequent flier program with a relative fair value approach. The Company also expects the classification and timing of recognition of certain ancillary fees to be impacted by adoption of ASU 2014-09. While the Company believes the adoption will not have a significant impact on earnings, the classification of certain revenues, such as bags, seats and other travel-related fees may be deemed part of the single performance obligation of providing passenger transportation. The Company expects that these revenues currently classified as non-ticket revenue, approximately $1 billion annually, will be reclassified to passenger revenue after adoption. 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 the Company for interim and annual periods beginning January 1, 2018 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 condensed 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 condensed 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 Company adopted this guidance on January 1, 2017. As a result, excess income tax benefits and deficiencies related to share-based compensation are now included within income tax expense rather than additional paid in capital. For the six months ended June 30, 2017 , $0.6 million of income tax deficiency related to share-based compensation was included within income tax expense on the Company's statements of operations. Additionally, excess income tax benefits and deficiencies for share-based payments are now included in net operating cash flows rather than net financing cash flows. The changes have been applied prospectively in accordance with the guidance and prior periods have not been adjusted. Accounting for Credit Losses In June 2016, the FASB issued ASU No. 2016-13, "Financial Instruments - Credit Losses." The standard requires the use of an "expected loss" model on certain types of financial instruments. The standard also amends the impairment model for available-for-sale securities and requires estimated credit losses to be recorded as allowances instead of reductions to amortized cost of the securities. This standard is effective for the Company for fiscal years, and interim periods within those years, beginning January 1, 2020, with early adoption permitted. The Company is evaluating the new guidance, but does not expect it to have a material impact on its financial statements. Statement of Cash Flows In August 2016, the FASB issued ASU No. 2016-15, "Statement of Cash Flows." The standard is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. This standard is effective for the Company for fiscal years, and interim periods within those years, beginning January 1, 2018, with early adoption permitted. The Company is evaluating the new guidance, but does not expect it to have a material impact on its financial statements.

Special Charges

Special Charges	6 Months Ended
	Jun. 30, 2017
Special Charges and Credits [Abstract]
Special Charges	Special Charges During the six months ended June 30, 2017 , the Company purchased one engine which was previously financed under an operating lease agreement. The purchase price of the engine was $8.1 million , comprised of a cash payment of $3.8 million and the non-cash application of maintenance and security deposits held by the previous lessor of $4.3 million . The Company estimated the fair value of the engine to be $3.1 million and has recorded the purchased engine at fair value within flight equipment on the condensed balance sheets. The Company determined the valuation of the engine based on a third-party appraisal considering the condition of the engine (a Level 3 measurement). The Company recognized $4.8 million as a cost of terminating the lease 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 engine, less other non-cash items of $0.2 million . During the six months ended June 30, 2016 , the Company purchased three A319 aircraft which were previously financed under operating lease agreements. The purchase price of the 3 aircraft was $65.9 million , comprised of a cash payment of $33.8 million and the non-cash application of maintenance and security deposits held by the previous lessor of $32.1 million . The Company estimated the fair value of the aircraft to be $41.2 million and has recorded the 3 purchased aircraft at fair value 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 $24.3 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 other non-cash items of $0.4 million .

Earnings per Share

Earnings per Share	6 Months Ended
	Jun. 30, 2017
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 June 30, Six Months Ended June 30, 2017 2016 2017 2016 (in thousands, except per share amounts) Numerator Net income $ 78,143 $ 73,084 $ 110,078 $ 135,004 Denominator Weighted-average shares outstanding, basic 69,370 70,770 69,359 71,173 Effect of dilutive stock awards 191 143 217 174 Adjusted weighted-average shares outstanding, diluted 69,561 70,913 69,576 71,347 Net income per share Basic earnings per common share $ 1.13 $ 1.03 $ 1.59 $ 1.90 Diluted earnings per common share $ 1.12 $ 1.03 $ 1.58 $ 1.89 Anti-dilutive weighted-average shares 17 54 52 69

Short-term Investment Securitie

Short-term Investment Securities	6 Months Ended
	Jun. 30, 2017
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 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 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. Unrealized gains and losses on investment securities are reflected as a component of accumulated other comprehensive income (AOCI). As of June 30, 2017 and December 31, 2016 , the Company had $100.5 million and $100.2 million in short-term available-for-sale investment securities, respectively. For the six months ended June 30, 2017 , these investments earned interest income at a weighted-average fixed rate of approximately 1.4% . For the three and six months ended June 30, 2017 , an unrealized loss of $11 thousand and $24 thousand , net of deferred taxes of $6 thousand and $14 thousand , respectively, was recorded within AOCI related to these investment securities. For the three and six months ended June 30, 2016 , the Company had no unrealized gains or losses related to these instruments as the Company did not invest in them until the third quarter of 2016. The Company has not recognized any realized gains or losses related to these securities as the Company has not transacted any sale of these securities. As of June 30, 2017 and December 31, 2016 , $46 thousand and $23 thousand , net of tax, respectively, remained in AOCI, related to these instruments.

Accrued Liabilities

Accrued Liabilities	6 Months Ended
	Jun. 30, 2017
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities Other current liabilities as of June 30, 2017 and December 31, 2016 consist of the following: June 30, 2017 December 31, 2016 (in thousands) Federal excise and other passenger taxes and fees payable $ 62,708 $ 42,064 Salaries and wages 49,109 54,578 Airport obligations 47,230 43,989 Aircraft maintenance 33,092 30,233 Aircraft and facility lease obligations 12,919 10,378 Interest payable 8,953 8,499 Fuel 7,846 14,828 Other 22,772 21,442 Other current liabilities $ 244,629 $ 226,011

Financial Instruments and Risk

Financial Instruments and Risk Management	6 Months Ended
	Jun. 30, 2017
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 the absolute exposure levels, each counterparty's credit ratings and the historical performance of 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. As of June 30, 2017 , the Company did not hold any derivatives with requirements to post collateral. The Company records financial derivative instruments at fair value, which includes an evaluation of each counterparty's credit risk. 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. Historically, the Company's fuel derivative contracts have generally consisted 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 have been 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 such instruments is determined using standard option valuation models. The Company accounts for its fuel derivative contracts at fair value and recognizes them in the condensed 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 six months ended June 30, 2017 and 2016 . 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. As of June 30, 2017 and December 31, 2016 , the Company did not have any outstanding fuel derivatives. 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 condensed 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 June 30, 2017 and December 31, 2016 , 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. During the three and six months ended June 30, 2017 and 2016 , there were no unrealized gains or losses recorded within AOCI related to these instruments as they settled in 2015. For the three and six months ended June 30, 2017 , the Company reclassified interest rate swap losses of $53 thousand and $107 thousand , net of tax of $31 thousand and $62 thousand , respectively, into earnings. For the three and six months ended June 30, 2016 , the Company reclassified interest rate swap losses of $56 thousand and $113 thousand , net of tax of $32 thousand and $65 thousand , respectively, into earnings. As of June 30, 2017 and December 31, 2016 , $1.2 million and $1.3 million , net of tax, respectively, remained in AOCI, related to these instruments.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2017
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. During the first quarter of 2017, the Company negotiated revisions to its A320 aircraft order. The Company originally had four A320neo aircraft scheduled for delivery in 2018 of which two were converted to A320ceo aircraft, to be delivered in 2017, and the remaining two are deferred until 2019. As of June 30, 2017 , the Company's aircraft orders consisted of the following: Airbus A320ceo A320neo A321ceo Total remainder of 2017 3 7 10 2018 5 5 10 2019 1 14 15 2020 16 16 2021 18 18 9 48 12 69 The Company also has six spare engine orders for V2500 SelectTwo 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 2017 through 2023 . Purchase commitments for these aircraft and spare engines, including estimated amounts for contractual price escalations and pre-delivery payments, are expected to be $413.2 million for the remainder of 2017 , $528.4 million in 2018 , $764.4 million in 2019 , $829.8 million in 2020 , $784.8 million in 2021 , and $24.6 million in 2022 and beyond . As of June 30, 2017 , the Company had secured debt financing commitments of $310.0 million for 8 aircraft, scheduled for delivery in the remainder of 2017, and did not have financing commitments in place for the remaining 61 Airbus aircraft currently on firm order, which are scheduled for delivery in 2017 through 2021 . Interest commitments related to the secured debt financing of 36 delivered aircraft as of June 30, 2017 are $25.5 million for the remainder of 2017, $47.5 million in 2018 , $43.3 million in 2019 , $39.0 million in 2020 , $34.8 million in 2021 , and $125.3 million in 2022 and beyond . For principal commitments related to these financed aircraft, refer to Note 10, Debt and Other Obligations. As of June 30, 2017 , principal and interest commitments related to the Company's future secured debt financing of 8 undelivered aircraft under bank debt is approximately $5.1 million for the remainder of 2017 , $32.6 million in 2018 , $32.4 million in 2019 , $33.3 million in 2020 , $32.1 million in 2021 , and $256.5 million in 2022 and beyond . As of June 30, 2017 , the Company had a fleet consisting of 104 A320 family aircraft. During the six months ended June 30, 2017 , the Company took delivery of seven aircraft financed under secured debt arrangements, two aircraft under operating leases and purchased one previously leased engine. For further discussion on the previously leased engine, refer to Note 3, Special Charges. The purchased aircraft are capitalized within flight equipment with depreciable lives of 25 years and estimated residual values of 10% . As of June 30, 2017 , the Company had 61 aircraft and 10 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 condensed balance sheets. 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 condensed balance sheets. 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. 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 A320ceos from 178 to 182 seats (reconfiguration). The reconfiguration of the aircraft commenced in the first quarter of 2016 and is expected to be completed in the fourth quarter of 2017 for a remaining committed cost of $1.0 million , as of June 30, 2017 . These amounts will be capitalized within flight equipment on the condensed balance sheets. 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 will reduce dependence on third-party facilities and contract maintenance. The lease agreement has a 30 -year term with two 10 -year extension options. Upon termination of the lease, title of the project, which will be fully depreciated, will automatically pass to the Authority. The Company completed the project during the first quarter of 2017 and as of June 30, 2017 , the Company had a remaining commitment of approximately $0.2 million related to this project. Future minimum lease payments under capital leases and noncancellable operating leases with initial or remaining terms in excess of one year at June 30, 2017 were as follows: Capital Leases Aircraft and Spare Engine Leases Property Facility Leases Total Operating and Capital Lease Obligations (in thousands) remainder of 2017 $ 268 $ 108,237 $ 21,496 $ 130,001 2018 537 206,595 41,024 248,156 2019 504 188,212 33,034 221,750 2020 188 180,235 21,817 202,240 2021 28 170,613 12,800 183,441 2022 and thereafter — 570,087 73,285 643,372 Total minimum lease payments $ 1,525 $ 1,423,979 $ 203,456 $ 1,628,960 Less amount representing interest 136 Present value of minimum lease payments $ 1,389 Less current portion 460 Long-term portion $ 929 The majority of the Company's capital lease obligations relate to the lease of computer equipment used by the Company's flight crew. Payments under this lease agreement are fixed for the 3 -year term of the lease which began in the second quarter of 2017. 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 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 $3.9 million for the remainder of 2017 , $7.0 million in 2018 , $5.7 million in 2019 , $5.4 million in 2020 , $5.5 million in 2021 , and $17.7 million in 2022 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 as long as the Company's cash balance does not fall below a certain level. As of June 30, 2017 , 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. The Company is contractually obligated to pay the following minimum guaranteed payments for its reservation system, advertising media, maintenance for new airport kiosks, data center, weather system and call center as of June 30, 2017 : $3.4 million for the remainder of 2017 , $4.9 million in 2018 , $0.8 million in 2019 , $0.6 million in 2020 , $0.2 million in 2021 , and $0.1 million thereafter . 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 June 30, 2017 and December 31, 2016 , 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 June 30, 2017 and December 31, 2016 , was $364.7 million and $234.6 million , respectively. Employees The Company has four union-represented employee groups that together represented approximately 74% of all employees at June 30, 2017 . The table below sets forth the Company's employee groups and status of the collective bargaining agreements as of June 30, 2017 . 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 43% Dispatchers Transport Workers Union (TWU) August 2018 1% Ramp Service Agents International Association of Machinists and Aerospace Workers (IAMAW) June 2020 4% 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 mediators and the parties continue to meet and work toward an amended agreement with the guidance of the mediator. Under the Railway Labor Act (RLA), the parties' current agreement remains in effect until an amended agreement is reached. In March 2016 , under the supervision of the 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 of which $8.4 million was recorded within salaries, wages and benefits in the condensed statement of operations for the six months ended June 30, 2016 . 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 $5.6 million and $5.7 million in health care claims as of June 30, 2017 and December 31, 2016 , respectively.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2017
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 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 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 June 30, 2017 and December 31, 2016 , the Company had no outstanding jet 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 June 30, 2017 and December 31, 2016 were as follows: June 30, 2017 December 31, 2016 Fair Value Level Hierarchy Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value (in millions) Senior term loans $ 435.0 $ 453.8 $ 451.9 $ 463.9 Level 3 Junior term loans 43.2 44.7 47.1 48.1 Level 3 Fixed-rate loans 216.3 221.5 — — Level 3 Class A enhanced equipment trust certificates 423.6 436.3 409.8 416.0 Level 2 Class B enhanced equipment trust certificates 100.0 102.3 103.6 105.7 Level 2 Total long-term debt $ 1,218.1 $ 1,258.6 $ 1,012.4 $ 1,033.7 Cash and Cash Equivalents Cash and cash equivalents at June 30, 2017 and December 31, 2016 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 June 30, 2017 and December 31, 2016 are comprised of available-for-sale asset-backed securities with contractual maturities of twelve months or less 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. Assets and liabilities measured at gross fair value on a recurring basis are summarized below: Fair Value Measurements as of June 30, 2017 Total Level Level Level (in millions) Cash and cash equivalents $ 869.2 $ 869.2 $ — $ — Short-term investment securities 100.5 100.5 — — Total assets $ 969.7 $ 969.7 $ — $ — Total liabilities $ — $ — $ — $ — Fair Value Measurements as of December 31, 2016 Total Level Level Level (in millions) Cash and cash equivalents $ 700.9 $ 700.9 $ — $ — Short-term investment securities 100.2 100.2 — — Total assets $ 801.1 $ 801.1 $ — $ — Total liabilities $ — $ — $ — $ — The Company had no transfers of assets or liabilities between any of the above levels during the periods ended June 30, 2017 and December 31, 2016 . 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.

Debt and Other Obligations

Debt and Other Obligations	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Debt and Other Obligations	Debt and Other Obligations As of June 30, 2017 , the Company held non-public and public debt instruments. Long-term debt is comprised of the following: As of Three Months Ended June 30, Six Months Ended June 30, June 30, 2017 December 31, 2016 2017 2016 2017 2016 (in millions) (weighted-average interest rates) Fixed-rate senior term loans due through 2027 $ 435.0 $ 451.9 4.10 % 4.10 % 4.10 % 4.10 % Fixed-rate junior term loans due through 2022 43.2 47.1 6.90 % 6.90 % 6.90 % 6.90 % Fixed-rate loans due through 2029 216.3 — 3.82 % N/A 3.82 % N/A Fixed-rate class A enhanced equipment trust certificates due through 2028 423.6 409.8 4.10 % 4.03 % 4.10 % 4.03 % Fixed-rate class B enhanced equipment trust certificates due through 2024 100.0 103.6 4.45 % 4.38 % 4.45 % 4.38 % Long-term debt $ 1,218.1 $ 1,012.4 Less current maturities 95.4 84.4 Less unamortized discounts 33.5 30.6 Total $ 1,089.2 $ 897.4 During the three and six months ended June 30, 2017 , the Company made scheduled principal payments of $39.8 million and $50.0 million on its outstanding debt obligations, respectively. During the three and six months ended June 30, 2016 , the Company made scheduled principal payments of $9.9 million and $19.6 million , on its outstanding debt obligations, respectively. At June 30, 2017 , long-term debt principal payments for the next five years and thereafter are as follows: June 30, 2017 (in millions) Remainder of 2017 $ 49.8 2018 97.9 2019 96.9 2020 96.1 2021 95.5 2022 and beyond 781.9 Total debt principal payments $ 1,218.1 Interest Expense Interest expense related to long-term debt consisted of the following: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 (in thousands) Senior term loans $ 4,619 $ 4,964 $ 9,290 $ 10,012 Junior term loans 775 905 1,578 1,842 Fixed-rate loans 1,586 — 1,744 — Class A enhanced equipment trust certificates 4,321 2,698 8,629 3,881 Class B enhanced equipment trust certificates 1,108 773 2,292 1,109 Commitment fees 28 30 58 65 Amortization of debt discounts 1,290 794 2,521 1,310 Total $ 13,727 $ 10,164 $ 26,112 $ 18,219

Basis of Presentation (Policies

Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2017
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 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, 2016 filed with the Securities and Exchange Commission on February 13, 2017.
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. The new guidance is effective for the Company in the first quarter of 2018. Entities have the option to use either a full retrospective or a modified retrospective approach to adopt ASU 2014-09. The Company currently anticipates utilizing the full retrospective method of adoption allowed by the standard, in order to provide for comparative results in all periods presented, and plans to adopt the standard as of January 1, 2018. While the Company is still evaluating the impact, it currently believes the most significant impact of this ASU will be the elimination of the incremental cost method for frequent flier program accounting, which will require the Company to re-value and record a liability associated with customer flight miles earned as part of the Company’s frequent flier program with a relative fair value approach. The Company also expects the classification and timing of recognition of certain ancillary fees to be impacted by adoption of ASU 2014-09. While the Company believes the adoption will not have a significant impact on earnings, the classification of certain revenues, such as bags, seats and other travel-related fees may be deemed part of the single performance obligation of providing passenger transportation. The Company expects that these revenues currently classified as non-ticket revenue, approximately $1 billion annually, will be reclassified to passenger revenue after adoption. 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 the Company for interim and annual periods beginning January 1, 2018 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 condensed 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 condensed 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 Company adopted this guidance on January 1, 2017. As a result, excess income tax benefits and deficiencies related to share-based compensation are now included within income tax expense rather than additional paid in capital. For the six months ended June 30, 2017 , $0.6 million of income tax deficiency related to share-based compensation was included within income tax expense on the Company's statements of operations. Additionally, excess income tax benefits and deficiencies for share-based payments are now included in net operating cash flows rather than net financing cash flows. The changes have been applied prospectively in accordance with the guidance and prior periods have not been adjusted. Accounting for Credit Losses In June 2016, the FASB issued ASU No. 2016-13, "Financial Instruments - Credit Losses." The standard requires the use of an "expected loss" model on certain types of financial instruments. The standard also amends the impairment model for available-for-sale securities and requires estimated credit losses to be recorded as allowances instead of reductions to amortized cost of the securities. This standard is effective for the Company for fiscal years, and interim periods within those years, beginning January 1, 2020, with early adoption permitted. The Company is evaluating the new guidance, but does not expect it to have a material impact on its financial statements. Statement of Cash Flows In August 2016, the FASB issued ASU No. 2016-15, "Statement of Cash Flows." The standard is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. This standard is effective for the Company for fiscal years, and interim periods within those years, beginning January 1, 2018, with early adoption permitted. The Company is evaluating the new guidance, but does not expect it to have a material impact on its financial statements.

Earnings per Share (Tables)

Earnings per Share (Tables)	6 Months Ended
	Jun. 30, 2017
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 June 30, Six Months Ended June 30, 2017 2016 2017 2016 (in thousands, except per share amounts) Numerator Net income $ 78,143 $ 73,084 $ 110,078 $ 135,004 Denominator Weighted-average shares outstanding, basic 69,370 70,770 69,359 71,173 Effect of dilutive stock awards 191 143 217 174 Adjusted weighted-average shares outstanding, diluted 69,561 70,913 69,576 71,347 Net income per share Basic earnings per common share $ 1.13 $ 1.03 $ 1.59 $ 1.90 Diluted earnings per common share $ 1.12 $ 1.03 $ 1.58 $ 1.89 Anti-dilutive weighted-average shares 17 54 52 69

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	6 Months Ended
	Jun. 30, 2017
Payables and Accruals [Abstract]
Accrued liabilities included in other current liabilities	Other current liabilities as of June 30, 2017 and December 31, 2016 consist of the following: June 30, 2017 December 31, 2016 (in thousands) Federal excise and other passenger taxes and fees payable $ 62,708 $ 42,064 Salaries and wages 49,109 54,578 Airport obligations 47,230 43,989 Aircraft maintenance 33,092 30,233 Aircraft and facility lease obligations 12,919 10,378 Interest payable 8,953 8,499 Fuel 7,846 14,828 Other 22,772 21,442 Other current liabilities $ 244,629 $ 226,011

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Operating Aircraft Leases	As of June 30, 2017 , the Company's aircraft orders consisted of the following: Airbus A320ceo A320neo A321ceo Total remainder of 2017 3 7 10 2018 5 5 10 2019 1 14 15 2020 16 16 2021 18 18 9 48 12 69
Future minimum lease payments under noncancelable operating leases	Future minimum lease payments under capital leases and noncancellable operating leases with initial or remaining terms in excess of one year at June 30, 2017 were as follows: Capital Leases Aircraft and Spare Engine Leases Property Facility Leases Total Operating and Capital Lease Obligations (in thousands) remainder of 2017 $ 268 $ 108,237 $ 21,496 $ 130,001 2018 537 206,595 41,024 248,156 2019 504 188,212 33,034 221,750 2020 188 180,235 21,817 202,240 2021 28 170,613 12,800 183,441 2022 and thereafter — 570,087 73,285 643,372 Total minimum lease payments $ 1,525 $ 1,423,979 $ 203,456 $ 1,628,960 Less amount representing interest 136 Present value of minimum lease payments $ 1,389 Less current portion 460 Long-term portion $ 929
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 June 30, 2017 . 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 43% Dispatchers Transport Workers Union (TWU) August 2018 1% Ramp Service Agents International Association of Machinists and Aerospace Workers (IAMAW) June 2020 4%

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2017
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 June 30, 2017 and December 31, 2016 were as follows: June 30, 2017 December 31, 2016 Fair Value Level Hierarchy Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value (in millions) Senior term loans $ 435.0 $ 453.8 $ 451.9 $ 463.9 Level 3 Junior term loans 43.2 44.7 47.1 48.1 Level 3 Fixed-rate loans 216.3 221.5 — — Level 3 Class A enhanced equipment trust certificates 423.6 436.3 409.8 416.0 Level 2 Class B enhanced equipment trust certificates 100.0 102.3 103.6 105.7 Level 2 Total long-term debt $ 1,218.1 $ 1,258.6 $ 1,012.4 $ 1,033.7
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 June 30, 2017 Total Level Level Level (in millions) Cash and cash equivalents $ 869.2 $ 869.2 $ — $ — Short-term investment securities 100.5 100.5 — — Total assets $ 969.7 $ 969.7 $ — $ — Total liabilities $ — $ — $ — $ — Fair Value Measurements as of December 31, 2016 Total Level Level Level (in millions) Cash and cash equivalents $ 700.9 $ 700.9 $ — $ — Short-term investment securities 100.2 100.2 — — Total assets $ 801.1 $ 801.1 $ — $ — Total liabilities $ — $ — $ — $ —

Debt and Other Obligations (Tab

Debt and Other Obligations (Tables)	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Schedule of Long-term Debt	Long-term debt is comprised of the following: As of Three Months Ended June 30, Six Months Ended June 30, June 30, 2017 December 31, 2016 2017 2016 2017 2016 (in millions) (weighted-average interest rates) Fixed-rate senior term loans due through 2027 $ 435.0 $ 451.9 4.10 % 4.10 % 4.10 % 4.10 % Fixed-rate junior term loans due through 2022 43.2 47.1 6.90 % 6.90 % 6.90 % 6.90 % Fixed-rate loans due through 2029 216.3 — 3.82 % N/A 3.82 % N/A Fixed-rate class A enhanced equipment trust certificates due through 2028 423.6 409.8 4.10 % 4.03 % 4.10 % 4.03 % Fixed-rate class B enhanced equipment trust certificates due through 2024 100.0 103.6 4.45 % 4.38 % 4.45 % 4.38 % Long-term debt $ 1,218.1 $ 1,012.4 Less current maturities 95.4 84.4 Less unamortized discounts 33.5 30.6 Total $ 1,089.2 $ 897.4
Schedule of Maturities of Long-term Debt	At June 30, 2017 , long-term debt principal payments for the next five years and thereafter are as follows: June 30, 2017 (in millions) Remainder of 2017 $ 49.8 2018 97.9 2019 96.9 2020 96.1 2021 95.5 2022 and beyond 781.9 Total debt principal payments $ 1,218.1
Schedule of Interest Expense, Long-term Debt	Interest expense related to long-term debt consisted of the following: Three Months Ended June 30, Six Months Ended June 30, 2017 2016 2017 2016 (in thousands) Senior term loans $ 4,619 $ 4,964 $ 9,290 $ 10,012 Junior term loans 775 905 1,578 1,842 Fixed-rate loans 1,586 — 1,744 — Class A enhanced equipment trust certificates 4,321 2,698 8,629 3,881 Class B enhanced equipment trust certificates 1,108 773 2,292 1,109 Commitment fees 28 30 58 65 Amortization of debt discounts 1,290 794 2,521 1,310 Total $ 13,727 $ 10,164 $ 26,112 $ 18,219

Recent Accounting Developments

Recent Accounting Developments Recent Accounting Developments (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017USD ($)
Adjustments for New Accounting Pronouncements [Line Items]
Income tax deficiency	$ 0.6
Accounting Standards Update 2014-09 [Member]
Adjustments for New Accounting Pronouncements [Line Items]
Expected increase to passenger revenue after adoption	$ 1,000

Special Charges (Details)

Special Charges (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)aircraft_engine	Jun. 30, 2016USD ($)aircraft
Property, Plant and Equipment [Line Items]
Purchase of property and equipment			$ 269,519	$ 303,175
Special charges	$ 0	$ 8,052	$ 4,776	$ 24,254
Airbus A319 [Member] | Aircraft [Member]
Property, Plant and Equipment [Line Items]
Number of previously leased engines | aircraft				3
Purchase price				$ 65,900
Purchase of property and equipment				33,800
Value of noncash consideration				32,100
Fair value of assets acquired				41,200
Special charges				24,300
Airbus A319 [Member] | Aircraft [Member] | Other Non-Cash Items [Member]
Property, Plant and Equipment [Line Items]
Value of noncash consideration				$ 400
Spare Engines [Member] | Spare Engines [Member]
Property, Plant and Equipment [Line Items]
Number of previously leased engines | aircraft_engine			1
Purchase price			$ 8,100
Purchase of property and equipment			3,800
Value of noncash consideration			4,300
Fair value of assets acquired			3,100
Special charges			4,800
Spare Engines [Member] | Spare Engines [Member] | Other Non-Cash Items [Member]
Property, Plant and Equipment [Line Items]
Value of noncash consideration			$ 200

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator
Net income	$ 78,143	$ 73,084	$ 110,078	$ 135,004
Denominator
Weighted-average shares outstanding, basic (in shares)	69,370	70,770	69,359	71,173
Effect of dilutive stock awards (in shares)	191	143	217	174
Adjusted weighted-average shares outstanding, diluted (in shares)	69,561	70,913	69,576	71,347
Net income per share
Basic earnings per common share (in dollars per share)	$ 1.13	$ 1.03	$ 1.59	$ 1.90
Diluted earnings per common share (in dollars per share)	$ 1.12	$ 1.03	$ 1.58	$ 1.89
Anti-dilutive weighted-average shares (in shares)	17	54	52	69

Short-term Investment Securit26

Short-term Investment Securities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Short-term investment securities	$ 100,464		$ 100,464		$ 100,155
Unrealized loss, net of deferred taxes	11	$ 0	24	$ 0
Tax effect of the unrealized gain (loss) on short-term investment securities	6	$ 0	14	$ 0
Accumulated other comprehensive loss	1,280		$ 1,280		1,345
Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average fixed rate			1.40%
Accumulated other comprehensive loss	$ 46		$ 46		$ 23

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Federal excise and other passenger taxes and fees payable	$ 62,708	$ 42,064
Salaries and wages	49,109	54,578
Airport obligations	47,230	43,989
Aircraft maintenance	33,092	30,233
Aircraft and facility lease obligations	12,919	10,378
Interest payable	8,953	8,499
Fuel	7,846	14,828
Other	22,772	21,442
Other current liabilities	$ 244,629	$ 226,011

Financial Instruments and Ris28

Financial Instruments and Risk Management - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Dec. 31, 2015aircraftderivative_instrument	Dec. 31, 2016USD ($)
Derivative [Line Items]
Interest rate derivative losses reclassified into earnings	$ 53	$ 56	$ 107	$ 113
Loss reclassified from AOCI into earnings, tax	31	32	62	65
Accumulated other comprehensive loss	1,280		1,280			$ 1,345
Airbus A321 [Member]
Derivative [Line Items]
Number of aircraft protected by interest rate derivatives schedule for delivery | aircraft					3
Interest Rate Swap [Member]
Derivative [Line Items]
Number of interest rate derivatives settled | derivative_instrument					6
Accumulated other comprehensive loss	1,200		1,200			$ 1,300
Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Interest rate derivative losses reclassified into earnings	$ 53	$ 56	$ 107	$ 113

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Aircraft Operating Leases (Details)	Jun. 30, 2017aircraft
Long-term Purchase Commitment [Line Items]
remainder of 2017	10
2,018	10
2,019	15
2,020	16
2,021	18
Total future aircraft to be received	69
Airbus [Member] | A320 [Member]
Long-term Purchase Commitment [Line Items]
remainder of 2017	3
2,018	5
2,019	1
Total future aircraft to be received	9
Airbus [Member] | A320NEO [Member]
Long-term Purchase Commitment [Line Items]
2,019	14
2,020	16
2,021	18
Total future aircraft to be received	48
Airbus [Member] | A321 [Member]
Long-term Purchase Commitment [Line Items]
remainder of 2017	7
2,018	5
Total future aircraft to be received	12

Commitments and Contingencies30

Commitments and Contingencies - Aircraft-Related Commitments and Financing Arrangements (Details) ft² in Thousands, $ in Millions	1 Months Ended		6 Months Ended
	Sep. 30, 2015ft²aextension_option	Jul. 31, 2015aircraftseat	Jun. 30, 2017USD ($)aircraft_engineaircraft
Unrecorded Unconditional Purchase Obligation [Line Items]
Aircraft scheduled for delivery | aircraft			69
Aircraft [Member]
Principal and Interest Commitments
Number of leased assets | aircraft			61
Spare Engines [Member]
Principal and Interest Commitments
Number of leased assets | aircraft_engine			10
Hangar Facility [Member] | Operating Lease [Member]
Principal and Interest Commitments
Estimated future project construction costs			$ 0.2
Area of Land | a	10
Real estate property (in square feet) | ft²	126
Operating leases, term	30 years
Number of renewal options | extension_option	2
Aircraft operating leases, renewal term	10 years
Secured Debt [Member]
Interest Commitments
Interest commitments, 2017			25.5
Interest commitments, 2018			47.5
Interest commitments, 2019			43.3
Interest commitments, 2020			39
Interest commitments, 2021			34.8
Interest commitments, 2022 and beyond			125.3
Principal and Interest Commitments
Principal and interest commitments, 2017			5.1
Principal and interest commitments, 2018			32.6
Principal and interest commitments, 2019			32.4
Principal and interest commitments, 2020			33.3
Principal and interest commitments, 2021			32.1
Principal and interest commitments, 2022 and beyond			$ 256.5
Aircraft [Member]
Committed Expenditures
Number of delivered aircraft with secured debt financing commitments | aircraft			7
Principal and Interest Commitments
Number of Delivered Leased Aircraft | aircraft			2
Depreciable lives			25 years
Estimated residual values			10.00%
Aircraft and Related Flight Equipment [Member]
Principal and Interest Commitments
Estimated future project construction costs			$ 1
2016 [Member] | Airbus [Member]
Committed Expenditures
Number of aircraft with secured debt financing commitments scheduled for delivery | aircraft			8
2017-2021 [Member] | Airbus [Member]
Committed Expenditures
Number of aircraft without secured financing commitments scheduled for delivery | aircraft			61
Aircraft and Related Flight Equipment [Member]
Committed Expenditures
Committed expenditures, remainder of 2017			$ 413.2
Committed expenditures, 2018			528.4
Committed expenditures, 2019			764.4
Committed expenditures, 2020			829.8
Committed expenditures, 2021			784.8
Committed expenditures, 2022 and beyond			24.6
Face amount, commitment for future issuance			310
Fixed Maintenance Reserve Payments, Aircraft and Related Flight Equipment [Member]
Committed Expenditures
Committed expenditures, remainder of 2017			3.9
Committed expenditures, 2018			7
Committed expenditures, 2019			5.7
Committed expenditures, 2020			5.4
Committed expenditures, 2021			5.5
Committed expenditures, 2022 and beyond			17.7
Non-aircraft Related Commitments [Member]
Committed Expenditures
Committed expenditures, remainder of 2017			3.4
Committed expenditures, 2018			4.9
Committed expenditures, 2019			0.8
Committed expenditures, 2020			0.6
Committed expenditures, 2021			0.2
Committed expenditures, 2022 and beyond			$ 0.1
V2500 SelectOne Engine [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of spare aircraft engines ordered | aircraft_engine			6
PurePower PW1100G-JM Engine [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of spare aircraft engines ordered | aircraft_engine			9
Spare Engines [Member] | Spare Engines [Member]
Principal and Interest Commitments
Number of previously leased engines | aircraft_engine			1
A-320-Neo [Member] | Airbus [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Aircraft scheduled for delivery | aircraft			48
A-320-Neo [Member] | 2018 [Member] | Airbus [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Aircraft scheduled for delivery | aircraft			4
A-320-Neo [Member] | 2019 [Member] | Airbus [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Aircraft scheduled for delivery | aircraft			2
Airbus A320 [Member] | Aircraft order contract renegotiation [Member] | 2016 [Member] | Airbus [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Aircraft scheduled for delivery | aircraft			2
A320 and A321 [Member] | Airbus [Member]
Committed Expenditures
Number of delivered aircraft with secured debt financing commitments | aircraft			36
Airbus A320 [Member]
Principal and Interest Commitments
Number of Aircraft Held | aircraft			104
A320 [Member] | Airbus [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Aircraft scheduled for delivery | aircraft			9
Principal and Interest Commitments
Number of aircrafts with increased seating capacity | aircraft		40
A320 [Member] | Airbus [Member] | Minimum [Member]
Principal and Interest Commitments
Number of seats | seat		178
A320 [Member] | Airbus [Member] | Maximum [Member]
Principal and Interest Commitments
Number of seats | seat		182

Commitments and Contingencies31

Commitments and Contingencies - Future Minimum Lease Payments Under Noncancelable Operating Leases (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017USD ($)
Operating Leased Assets [Line Items]
Capital Leases of Lessee, Lease Term	3 years
Total Operating and Capital Lease Obligations
remainder of 2017	$ 130,001
2,018	248,156
2,019	221,750
2,020	202,240
2,021	183,441
2022 and thereafter	643,372
Total minimum lease payments	1,628,960
Aircraft and Spare Engine Leases [Member]
Capital Leases
remainder of 2017	268
2,018	537
2,019	504
2,020	188
2,021	28
2022 and thereafter	0
Operating Leases
remainder of 2017	108,237
2,018	206,595
2,019	188,212
2,020	180,235
2,021	170,613
2022 and thereafter	570,087
Total minimum lease payments	1,423,979
Total Operating and Capital Lease Obligations
Capital Leases, Future Minimum Payments Due	1,525
Capital Leases, Future Minimum Payments, Interest Included in Payments	136
Capital Lease Obligations, Current	460
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	1,389
Capital Lease Obligations, Noncurrent	929
Property Facility Leases [Member]
Operating Leases
remainder of 2017	21,496
2,018	41,024
2,019	33,034
2,020	21,817
2,021	12,800
2022 and thereafter	73,285
Total minimum lease payments	$ 203,456

Commitments and Contingencies32

Commitments and Contingencies - Credit Card Processing Arrangements (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Restricted cash holdbacks	$ 0	$ 0
Maximum Potential Exposure to Cash Holdbacks from Credit Card Processors	$ 364,700,000	$ 234,600,000

Commitments and Contingencies33

Commitments and Contingencies - Employees (Details) $ in Millions	1 Months Ended	6 Months Ended
	Mar. 31, 2016	Jun. 30, 2017USD ($)employee_group	Jun. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Association of Flight Attendants [Member]
Concentration Risk [Line Items]
Tentative collective bargaining agreement, contract term	5 years
Ratification incentive payment			$ 9.6
Increase (Decrease) in Employee Related Liabilities			$ 8.4
Health Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Accrued health care claims		$ 5.6		$ 5.7
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member]
Concentration Risk [Line Items]
Number of union-represented employee groups | employee_group		4
Company's employees covered under collective bargaining agreements (as a percent)		74.00%
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)		43.00%
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)		4.00%

Fair Value Measurements - Long-

Fair Value Measurements - Long-term Debt (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Carrying Value	$ 1,218.1	$ 1,012.4
Senior Loans [Member]
Debt Instrument [Line Items]
Carrying Value	435	451.9
Junior Loans [Member]
Debt Instrument [Line Items]
Carrying Value	43.2	47.1
Fixed Rate Loan [Member]
Debt Instrument [Line Items]
Carrying Value	216.3	0
Equipment Notes, Series A [Member]
Debt Instrument [Line Items]
Carrying Value	423.6	409.8
Equipment Notes, Series B [Member]
Debt Instrument [Line Items]
Carrying Value	100	103.6
Estimated Fair Value [Member]
Debt Instrument [Line Items]
Estimated Fair Value	1,258.6	1,033.7
Estimated Fair Value [Member] | Level 3 [Member] | Senior Loans [Member]
Debt Instrument [Line Items]
Estimated Fair Value	453.8	463.9
Estimated Fair Value [Member] | Level 3 [Member] | Junior Loans [Member]
Debt Instrument [Line Items]
Estimated Fair Value	44.7	48.1
Estimated Fair Value [Member] | Level 3 [Member] | Fixed Rate Loan [Member]
Debt Instrument [Line Items]
Estimated Fair Value	221.5	0
Estimated Fair Value [Member] | Level 2 [Member] | Equipment Notes, Series A [Member]
Debt Instrument [Line Items]
Estimated Fair Value	436.3	416
Estimated Fair Value [Member] | Level 2 [Member] | Equipment Notes, Series B [Member]
Debt Instrument [Line Items]
Estimated Fair Value	$ 102.3	$ 105.7

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 869.2	$ 700.9
Short-term investment securities	100.5	100.2
Total assets	969.7	801.1
Total liabilities	0	0
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	869.2	700.9
Short-term investment securities	100.5	100.2
Total assets	969.7	801.1
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
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
Total assets	0	0
Total liabilities	$ 0	$ 0

Debt and Other Obligations (Det

Debt and Other Obligations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term debt	$ 1,218,100		$ 1,218,100		$ 1,012,400
Less current maturities	95,428		95,428		84,354
Less unamortized discounts	33,500		33,500		30,600
Total	1,089,159		1,089,159		897,359
Repayments of debt obligations	39,800	$ 9,900	50,000	$ 19,600
Senior Loans [Member]
Debt Instrument [Line Items]
Long-term debt	$ 435,000		$ 435,000		451,900
Weighted-average interest rate	4.10%	4.10%	4.10%	4.10%
Junior Loans [Member]
Debt Instrument [Line Items]
Long-term debt	$ 43,200		$ 43,200		47,100
Weighted-average interest rate	6.90%	6.90%	6.90%	6.90%
Fixed Rate Loan [Member]
Debt Instrument [Line Items]
Long-term debt	$ 216,300		$ 216,300		0
Weighted-average interest rate	3.82%		3.82%
Equipment Notes, Series A [Member]
Debt Instrument [Line Items]
Long-term debt	$ 423,600		$ 423,600		409,800
Weighted-average interest rate	4.10%	4.03%	4.10%	4.03%
Equipment Notes, Series B [Member]
Debt Instrument [Line Items]
Long-term debt	$ 100,000		$ 100,000		$ 103,600
Weighted-average interest rate	4.45%	4.38%	4.45%	4.38%

Debt and Other Obligations - Fu

Debt and Other Obligations - Future Maturities (Details) $ in Millions	Jun. 30, 2017USD ($)
Debt Disclosure [Abstract]
Remainder of 2017	$ 49.8
2,018	97.9
2,019	96.9
2,020	96.1
2,021	95.5
2022 and beyond	781.9
Total debt principal payments	$ 1,218.1

Debt and Other Obligations - In

Debt and Other Obligations - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Debt Instrument [Line Items]
Commitment fees	$ 28	$ 30	$ 58	$ 65
Amortization of debt discounts	1,290	794	2,521	1,310
Total	13,727	10,164	26,112	18,219
Senior Loans [Member]
Debt Instrument [Line Items]
Interest expense, term loans	4,619	4,964	9,290	10,012
Junior Loans [Member]
Debt Instrument [Line Items]
Interest expense, term loans	775	905	1,578	1,842
Fixed Rate Loan [Member]
Debt Instrument [Line Items]
Interest expense, term loans	1,586	0	1,744	0
Equipment Notes, Series A [Member]
Debt Instrument [Line Items]
Interest expense, term loans	4,321	2,698	8,629	3,881
Equipment Notes, Series B [Member]
Debt Instrument [Line Items]
Interest expense, term loans	$ 1,108	$ 773	$ 2,292	$ 1,109