Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ 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
Quarterly Financial Data [Abstract]
Revenue	$ 1,413	$ 1,424	$ 1,368	$ 1,371	$ 1,330	$ 1,141	$ 1,147	$ 1,154	$ 5,576	$ 4,772	$ 4,762
Operating income	182	207	193	163	173	197	224	226	745	820	981
Net income (loss) attributable to Frontier common shareholders	$ (156)	$ (81)	$ (28)	$ (51)	$ 14	$ 42	$ 38	$ 39	$ (316)	$ 133	$ 113
Basic net income (loss) per share attributable to Frontier common shareholders	$ (0.14)	$ (0.07)	$ (0.03)	$ (0.05)	$ 0.01	$ 0.04	$ 0.04	$ 0.04	$ (0.29)	$ 0.13	$ 0.11