Net Income Per Common Share (Calculation Of Net Income Per Common Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net Income Per Common Share [Abstract]
Net income attributable to common shareholders of Frontier	$ 35,400	$ 67,000	$ 45,080	$ 111,757
Less: Dividends paid on unvested restricted stock awards	(632)	(717)	(1,908)	(2,189)
Total basic and diluted net income attributable to common shareholders of Frontier	$ 34,768	$ 66,283	$ 43,172	$ 109,568
Total weighted average shares and unvested restricted stock awards outstanding - basic (in shares)	999,826	998,488	999,017	997,437
Less: Weighted average unvested restricted stock awards (in shares)	(6,711)	(7,193)	(6,537)	(7,137)
Total weighted average shares outstanding - basic (in shares)	993,115	991,295	992,480	990,300
Net income per share attributable to common shareholders of Frontier (in dollars per share)	$ 0.04	$ 0.07	$ 0.04	$ 0.11
Effect of dilutive shares (in shares)	990	163	922	667
Total weighted average shares outstanding - diluted (in shares)	994,105	991,458	993,402	990,967
Net income per share attributable to common shareholders of Frontier (in dollars per share)	$ 0.04	$ 0.07	$ 0.04	$ 0.11