Net Income Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net income used for basic and diluted earnings per common share [Abstract]
Net income attributable to common shareholders of Frontier	$ 24,879	$ 67,000	$ 17,989	$ 26,768	$ 42,247	$ 20,395	$ 32,261	$ 54,711	$ 136,636	$ 149,614	$ 152,673
Less: Dividends allocated to unvested restricted stock awards									(2,901)	(3,743)	(3,072)
Total basic and diluted net income attributable to common shareholders of Frontier									$ 133,735	$ 145,871	$ 149,601
Basic earnings per common share [Abstract]
Total weighted average shares and unvested restricted stock awards outstanding - basic (in shares)									997,665,000	994,753,000	653,248,000
Less: Weighted average unvested restricted stock awards (in shares)									(7,128,000)	(4,901,000)	(3,420,000)
Total weighted average shares outstanding - basic (in shares)									990,537,000	989,852,000	649,828,000
Net income per share attributable to common shareholders of Frontier (in dollars per share)	$ 0.02	$ 0.07	$ 0.02	$ 0.03	$ 0.04	$ 0.02	$ 0.03	$ 0.05	$ 0.14	$ 0.15	$ 0.23
Diluted earnings per common share [Abstract]
Total weighted average shares outstanding - basic (in shares)									990,537,000	989,852,000	649,828,000
Effect of dilutive shares (in shares)									1,263,000	1,415,000	1,163,000
Effect of dilutive stock units (in shares)									0	557,000	0
Total weighted average shares outstanding - diluted (in shares)									991,800,000	991,824,000	650,991,000
Net income per share attributable to common shareholders of Frontier (in dollars per share)									$ 0.13	$ 0.15	$ 0.23
Employee Stock Option [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	895,000	1,116,000
Exercise price range of stock options related to employee compensation plans - lower range limit (in dollars per share)									$ 10.44	$ 8.19	$ 10.44
Exercise price range of stock options related to employee compensation plans - upper range limit (in dollars per share)									$ 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)									864,114	557,480	434,765