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
	Mar. 31, 2014	Mar. 31, 2013
Net Income Per Common Share [Abstract]
Net income attributable to common shareholders of Frontier	$ 39,274	$ 48,140
Less: Dividends paid on unvested restricted stock awards	(767)	(521)
Total basic and diluted net income attributable to common shareholders of Frontier	$ 38,507	$ 47,619
Total weighted average shares and unvested restricted stock awards outstanding - basic (in shares)	1,000,960	998,146
Less: Weighted average unvested restricted stock awards (in shares)	(6,934)	(6,273)
Total weighted average shares outstanding - basic (in shares)	994,026	991,873
Basic net income per share attributable to common shareholders of Frontier	$ 0.04	$ 0.05
Effect of dilutive shares (in shares)	1,502	675
Total weighted average shares outstanding - diluted (in shares)	995,528	992,548
Diluted net income per common share attributable to common shareholders of Frontier	$ 0.04	$ 0.05