Net Income Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net income used for basic and diluted earnings per common share [Abstract]
Net income attributable to common shareholders of Frontier	$ 67,000	$ 20,395	$ 111,757	$ 107,367
Less: Dividends paid on unvested restricted stock awards	(717)	(914)	(2,189)	(2,835)
Total basic and diluted net income attributable to common shareholders of Frontier	$ 66,283	$ 19,481	$ 109,568	$ 104,532
Basic earnings per common share [Abstract]
Total weighted average shares and unvested restricted stock awards outstanding - basic (in shares)	998,488,000	995,188,000	997,437,000	994,642,000
Less: Weighted average unvested restricted stock awards (in shares)	(7,193,000)	(4,929,000)	(7,137,000)	(4,917,000)
Total weighted average shares outstanding - basic (in shares)	991,295,000	990,259,000	990,300,000	989,725,000
Net income per share attributable to common shareholders of Frontier (in dollars per share)	$ 0.07	$ 0.02	$ 0.11	$ 0.11
Diluted earnings per common share [Abstract]
Total weighted average shares outstanding - basic (in shares)	991,295,000	990,259,000	990,300,000	989,725,000
Effect of dilutive shares (in shares)	163,000	535,000	667,000	1,478,000
Effect of dilutive stock units (in shares)	0	490,000	0	490,000
Total weighted average shares outstanding - diluted (in shares)	991,458,000	991,284,000	990,967,000	991,693,000
Net income per share attributable to common shareholders of Frontier (in dollars per share)	$ 0.07	$ 0.02	$ 0.11	$ 0.11
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the computation of diluted earnings per share (in shares)	540,000	930,000	540,000	930,000
Exercise price range of stock options related to employee compensation plans - lower range limit (in dollars per share)	$ 8.19	$ 8.19	$ 8.19	$ 8.19
Exercise price range of stock options related to employee compensation plans - upper range limit (in dollars per share)	$ 14.15	$ 14.15	$ 14.15	$ 14.15
Non-Employee Directors' Deferred Fee Plan and Equity Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the computation of diluted earnings per share (in shares)			788,165	490,018