| Cover Page | Jul. 22, 2020 |
| Entity Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Jul. 22, 2020 |
| Entity Registrant Name | SPIRIT AIRLINES, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-35186 |
| Entity Tax Identification Number | 38-1747023 |
| Entity Address, Address Line One | 2800 Executive Way |
| Entity Address, City or Town | Miramar, |
| Entity Address, State or Province | FL |
| Entity Address, Postal Zip Code | 33025 |
| City Area Code | 954 |
| Local Phone Number | 447-7920 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001498710 |
| Amendment Flag | false |
| CommonStock,$0.0001parvalue [Member] | |
| Entity Information [Line Items] | |
| Title of 12(b) Security | Common Stock, $0.0001 par value |
| Trading Symbol | SAVE |
| Security Exchange Name | NYSE |
| Series A Preferred Stock Purchase Rights [Member] | |
| Entity Information [Line Items] | |
| Title of 12(b) Security | Series A Preferred Stock Purchase Rights |
| Trading Symbol | SAVE |
| Security Exchange Name | NYSE |
