Net Income (Loss) Per Share (Calculation Of Net Income (Loss) Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Income (Loss) Per Share [Abstract]
Net Income (Loss) Available to Common Stockholders, Basic	$ (156)	$ (81)	$ (28)	$ (51)	$ 14	$ 42	$ 38	$ 39	$ (316)	$ 133	$ 113
Less: Dividends paid on unvested restricted stock awards									(3)	(3)	(3)
Total basic and diluted net income (loss) attributable to Frontier common shareholders									$ (319)	$ 130	$ 110
Total weighted average shares and unvested restricted stock awards outstanding - basic (in shares)									1,091,798	1,001,812	999,126
Less: Weighted average unvested restricted stock awards (in shares)									(7,192)	(7,394)	(6,467)
Total weighted average shares outstanding - basic (in shares)									1,084,606	994,418	992,659
Net income (loss) per share attributable to common shareholders of Frontier (in dollars per share)	$ (0.14)	$ (0.07)	$ (0.03)	$ (0.05)	$ 0.01	$ 0.04	$ 0.04	$ 0.04	$ (0.29)	$ 0.13	$ 0.11
Effect of dilutive shares (in shares)										3,744	1,338
Total weighted average shares outstanding - diluted (in shares)									1,084,606	998,162	993,997
Diluted net income (loss) per share attributable to Frontier common shareholders									$ (0.29)	$ 0.13	$ 0.11