Net Income Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net income used for basic and diluted earnings per common share [Abstract]
Net income attributable to common shareholders of Frontier	$ 42,247	$ 20,395	$ 32,261	$ 54,711	$ 45,992	$ 28,995	$ 35,121	$ 42,565	$ 149,614	$ 152,673	$ 120,783
Less: Dividends allocated to unvested restricted stock awards									(3,743)	(3,072)	(2,248)
Total basic and diluted net income attributable to common shareholders of Frontier									$ 145,871	$ 149,601	$ 118,535
Basic earnings per common share [Abstract]
Total weighted average shares and unvested restricted stock awards outstanding - basic (in shares)									994,753	653,248	312,183
Less: Weighted average unvested restricted stock awards (in shares)									(4,901)	(3,420)	(2,162)
Total weighted average shares outstanding - basic (in shares)									989,852	649,828	310,021
Net income per share attributable to common shareholders of Frontier (in dollars per share)									$ 0.15	$ 0.23	$ 0.38
Diluted earnings per common share [Abstract]
Total weighted average shares outstanding - basic (in shares)									989,852	649,828	310,021
Effect of dilutive shares (in shares)									1,972	1,163	92
Total weighted average shares outstanding - diluted (in shares)									991,824	650,991	310,113
Net income per share attributable to common shareholders of Frontier (in dollars per share)									$ 0.15	$ 0.23	$ 0.38
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)									895,000	1,116,000	3,551,000
Exercise price range of stock options related to employee compensation plans - lower range limit (in dollars per share)									$ 8.19	$ 10.44	$ 8.19
Exercise price range of stock options related to employee compensation plans - upper range limit (in dollars per share)									$ 14.15	$ 14.15	$ 18.46
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)									557,480	434,765	440,463