Basis of Presentation	6 Months Ended
Basis of Presentation	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of Spirit Airlines, Inc. (“Spirit”) and its consolidated subsidiaries (together with Spirit, the “Company”). These unaudited condensed consolidated 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 audited annual financial statements prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission for Form 10-Q. These unaudited interim condensed consolidated financial statements should be read in conjunction with the audited financial statements of the Company and notes thereto included in the Company's Annual Report on Form 10-K for the year ended December 31, 2023 filed with the Securities and Exchange Commission on February 9, 2024. 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 consolidated financial statements are not necessarily indicative of the results that may be expected for other interim periods or for the full year. The air transportation business is subject to significant seasonal fluctuations as demand is generally greater in the second and third quarters of each year. The air transportation business is volatile and highly affected by economic cycles and trends. The Company’s condensed consolidated financial statements have been prepared assuming that it will continue as a going concern, which contemplates continuity of operations, realization of assets and liquidation of liabilities in the normal course of business. The Company has been impacted by an increasingly challenging pricing environment. Moreover, the expected short-term impact of certain policy changes, such as the removal of change and cancel fees, have negatively affected revenue performance. The Company expects these trends to continue for at least the remainder of 2024, which may create uncertainty in operating results. The Company is currently in discussions with representatives of certain of its bondholders to negotiate the terms for refinancing or extending its existing 8.00% senior secured notes due in September 2025, as well as representatives of certain of its convertible notes due 2026. There is no guarantee that the Company will be able to extend or refinance its existing 8.00% senior secured notes due in September 2025 or its convertible notes due 2026. Absent additional amendment to the Company's agreement with its credit card processor, the failure to refinance or extend the specified minimum outstanding principal amount of the Company's 8.00% senior secured notes due 2025 by September 20, 2024, will result in an advancement of the termination date of such agreement from December 31, 2025 to December 31, 2024. That may, in turn, compel management to pursue further negotiations with the Company's credit card processor and other parties, or may require various additional measures to conserve or raise additional liquidity, including further recapitalizing or restructuring the business. In addition, the Company is pursuing plans to refinance the fixed-rate debt associated with the Company's owned aircraft. There can be no guarantee that such measures will be successful. The Company has assessed the impact of the current pricing environment and its planned policy changes on its liquidity requirements over the next 12 months and has concluded that it is probable the Company will have sufficient liquidity to meet its future cash needs with cash and cash equivalents, cash flows from operations, the implementation of discretionary cost reduction strategies, execution of planned sale leaseback transactions related to owned aircraft and, in the event the specified minimum outstanding principal amount of its existing 8.00% senior secured notes due in September 2025 is not extended or refinanced prior to September 20, 2024, renegotiation of terms with the credit card processor and other parties to facilitate payment processing.