| Cover | Feb. 02, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Feb. 2, 2022 |
| Entity Registrant Name | Frontier Group Holdings, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, State or Province | CO |
| Entity File Number | 001-40304 |
| Entity Tax Identification Number | 46-3681866 |
| Entity Address, Address Line One | 4545 Airport Way |
| Entity Address, City or Town | Denver |
| Entity Address, Postal Zip Code | 80239 |
| City Area Code | 720 |
| Local Phone Number | 374-4200 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.001 par value per share |
| Trading Symbol | ULCC |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001670076 |
| Amendment Flag | false |
