Quarterly Financial Data (Schedule Of Quarterly Financial Data) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Data [Abstract]
Revenue	$ 2,409	$ 2,524	$ 2,608	$ 1,355	$ 1,413	$ 1,424	$ 1,368	$ 1,371	$ 8,896	$ 5,576	$ 4,772
Operating income	255	264	311	58	182	207	193	163	888	745	820
Net income (loss) attributable to Frontier common shareholders	$ (133)	$ (134)	$ (80)	$ (240)	$ (156)	$ (81)	$ (28)	$ (51)	$ (587)	$ (316)	$ 133
Basic net income (loss) per share attributable to Frontier common shareholders	$ (0.12)	$ (0.12)	$ (0.07)	$ (0.21)	$ (0.14)	$ (0.07)	$ (0.03)	$ (0.05)	$ (0.51)	$ (0.29)	$ 0.13