Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2021
Long-Term Debt [Abstract]
Long-Term Debt	($ in millions)         Principal debt outstanding, December 31, 2020 (Predecessor) $ 16,769 Issuance of incremental term loan 225 Issuance of Takeback Notes 750 Conversion of Unsecured Senior Notes (10,949) Repayment of long term subsidiary debt at security (1) Principal debt outstanding, April 30, 2021 (Predecessor) $ 6,794 Less: Unamortized debt issuance costs (2) Less: Unamortized premium (discount) (39) Less: Long-term debt due within one year (15) Carrying amount of debt, April 30, 2021 (Predecessor) $ 6,738 Fresh start accounting fair value adjustment 277(1) Total Long-term debt, April 30, 2021 (Predecessor) $ 7,015         Principal debt outstanding, April 30, 2021 (Successor) $ 6,794 New borrowings 1,000 Repayment of long-term debt at maturity (17) Principal debt outstanding, December 31, 2021 (Successor) $ 7,777(2) Plus: Unamortized fair value adjustment 219 Less: Unamortized debt issuance costs (13) Less: Long-term debt due within one year (15) Long-term debt, December 31, 2021 (Successor) $ 7,968 (1)Upon emergence, Frontier adjusted the carrying value of our debt to fair value. The adjustment consisted of the elimination of the existing unamortized debt issuance costs and unamortized discounts and recording a balance of $236 million as a fair value adjustment. The fair value accounting adjustment is being amortized into interest expense using the effective interest method. This amortization resulted in $18 million for the eight months ended December 31, 2021.(2)Weighted average interest rate as of December 31, 2021 was 5.702%. Interest rate includes amortization of debt issuance costs and debt discounts. The interest rate at December 31, 2021 represent a weighted average of multiple issuances.‎
Schedule Of Secured And Unsecured Debt	Successor Predecessor December 31, 2021 December 31, 2020 Principal Interest Principal Interest ($ in millions) Outstanding Rate Outstanding Rate Secured debt issued by Frontier Term loan due 10/8/2027 $ 1,464 4.500% (Variable) $ 1,250 5.750% (Variable) First lien notes due 10/15/2027 1,150 5.875% 1,150 5.875% First lien notes due 5/1/2028 1,550 5.000% 1,550 5.000% Second lien notes due 11/1/2029 750 5.875% - Second lien notes due 5/1/2029 1,000 6.750% 1,000 6.750% Second lien notes due 2030 1,000 6.000% - IDRB due 5/1/2030 13 6.200% 14 6.200% Total secured debt issued by Frontier 6,927 4,964 Unsecured debt issued by Frontier Senior notes due 4/15/2020 - 172 8.500% Senior notes due 9/15/2020 - 55 8.875% Senior notes due 7/1/2021 - 89 9.250% Senior notes due 9/15/2021 - 220 6.250% Senior notes due 4/15/2022 - 500 8.750% Senior notes due 9/15/2022 - 2,188 10.500% Senior notes due 1/15/2023 - 850 7.125% Senior notes due 4/15/2024 - 750 7.625% Senior notes due 1/15/2025 - 775 6.875% Senior notes due 9/15/2025 - 3,600 11.000% Debentures due 11/1/2025 - 138 7.000% Debentures due 8/15/2026 - 2 6.800% Senior notes due 1/15/2027 - 346 7.875% Senior notes due 8/15/2031 - 945 9.000% Debentures due 10/1/2034 - 1 7.680% Debentures due 7/1/2035 - 125 7.450% Debentures due 10/1/2046 - 193 7.050% Total unsecured debt issued by Frontier - 10,949 Secured debt issued by subsidiaries Debentures due 11/15/2031 100 8.500% 100 8.500% RUS loan contracts due 1/3/2028 - 6 6.154% Total secured debt issued by subsidiaries 100 106 Unsecured debt issued by subsidiaries Debentures due 5/15/2027 200 6.750% 200 6.750% Debentures due 2/1/2028 300 6.860% 300 6.860% Debentures due 2/15/2028 200 6.730% 200 6.730% Debentures due 10/15/2029 50 8.400% 50 8.400% Total unsecured debt issued by subsidiaries 750 750 Debt prior to reclassification to liabilities subject to compromise 7,777 5.702%(1) 16,769 8.188%(1) Less: debt subject to compromise - (10,949) Unamortized fair value adjustment 219 - Carrying amount of Total Debt $ 7,996 $ 5,820 (1) Interest rate represents a weighted average of the stated interest rates of multiple issuances