Net Income (Loss) Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2021
Net Income (Loss) Per Common Share [Abstract]
Reconciliation Of Net Loss Per Share	Successor Predecessor For the eight For the four For the year For the year months ended months ended ended ended December 31, April 30, December 31, December 31, 2021 2021 2020 2019 ($ in millions and shares in thousands, except per share amounts) Net income (loss) used for basic and diluted earnings (loss) per share: Net income (loss) attributable to Frontier common shareholders $ 414  $ 4,541  $ (402) $ (5,911) Less: Dividends paid on unvested restricted stock awards - - - - Total basic net income (loss) attributable to Frontier common shareholders $ 414  $ 4,541  $ (402) $ (5,911) Effect of loss related to dilutive stock units - - - - Total diluted net income (loss) attributable to Frontier common shareholders $ 414  $ 4,541  $ (402) $ (5,911) Basic earnings (loss) per share: Total weighted average shares and unvested restricted stock awards outstanding - basic 244,405  104,799  104,944  105,356  Less: Weighted average unvested restricted stock awards - (215) (477) (1,291) Total weighted average shares outstanding - basic 244,405  104,584  104,467  104,065  Basic net income (loss) per share attributable to Frontier common shareholders $ 1.69  $ 43.42  $ (3.85) $ (56.80) Diluted earnings (loss) per share: Total weighted average shares outstanding - basic 244,405  104,584  104,467  104,065  Effect of dilutive shares 1,480  340  - - Total weighted average shares outstanding - diluted 245,885  104,924  104,467  104,065  Diluted net income (loss) per share attributable to Frontier common shareholders $ 1.68  $ 43.28  $ (3.85) $ (56.80)