Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Data (Unaudited) [Abstract]
Revenue	$ 1,330,305	$ 1,140,874	$ 1,147,265	$ 1,154,046	$ 1,180,369	$ 1,185,278	$ 1,190,533	$ 1,205,396	$ 4,772,490	$ 4,761,576	$ 5,011,853
Operating income	172,543	197,031	224,342	226,025	257,569	206,172	266,156	250,824	819,941	980,721	987,168
Net income attributable to common shareholders of Frontier	$ 13,946	$ 41,993	$ 37,680	$ 39,274	$ 67,755	$ 35,400	$ (38,460)	$ 48,140	$ 132,893	$ 112,835	$ 136,636
Basic net income per common share attributable to common shareholders of Frontier	$ 0.01	$ 0.04	$ 0.04	$ 0.04	$ 0.07	$ 0.04	$ (0.04)	$ 0.05	$ 0.13	$ 0.11	$ 0.14