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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net Income Per Common Share [Abstract]
Net income (loss) attributable to common shareholders of Frontier	$ 37,680	$ (38,460)	$ 76,954	$ 9,680
Less: Dividends paid on unvested restricted stock awards	(746)	(755)	(1,513)	(1,276)
Total basic and diluted net income (loss) attributable to common shareholders of Frontier	$ 36,934	$ (39,215)	$ 75,441	$ 8,404
Total weighted average shares and unvested restricted stock awards outstanding - basic (in shares)	1,002,191	999,234	1,001,474	998,770
Less: Weighted average unvested restricted stock awards (in shares)	(7,563)	(6,623)	(7,189)	(6,606)
Total weighted average shares outstanding - basic (in shares)	994,628	992,611	994,285	992,164
Basic net income (loss) per share attributable to common shareholders of Frontier	$ 0.04	$ (0.04)	$ 0.08	$ 0.01
Effect of dilutive shares (in shares)	2,157	603	2,645	449
Total weighted average shares outstanding - diluted (in shares)	996,785	993,214	996,930	992,613
Diluted net income (loss) per common share attributable to common shareholders of Frontier	$ 0.04	$ (0.04)	$ 0.08	$ 0.01