Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation of the Federal income tax statutory rates to the effective rates [Abstract]
Consolidated tax provision at federal statutory rate (in hundredths)	35.00%	35.00%	35.00%
State income tax provisions, net of federal income tax benefit (in hundredths)	2.80%	3.20%	2.80%
Reversal of tax credits (in hundredths)	4.40%
Non-deductible transaction costs (in hundredths)	0.00%	4.20%	0.00%
Tax reserve adjustment (in hundredths)	(5.50%)	0.40%	0.00%
All other, net (in hundredths)	(0.80%)	(0.30%)	(1.60%)
Effective tax rate (in hundredths)	35.90%	42.50%	36.20%
Impact of charge resulting from enactment of Michigan Corporate Income Tax that eliminated certain future tax deductions	$ 10,800,000
Reversal of reserve for uncertain tax positions	8,600,000
Reduction of deferred tax balances based on application of enacted state tax statutes	6,800,000
Reduced deferred tax assets		11,300,000
Income tax charge resulting from health care reform legislation		4,100,000
Deferred income tax liabilities [Abstract]
Property, plant and equipment basis differences	1,896,666,000	1,448,061,000
Intangibles	997,455,000	1,145,760,000
Other, net	17,584,000	10,170,000
Total	2,911,705,000	2,603,991,000
Deferred income tax assets [Abstract]
Pension liability	246,714,000	176,579,000
Tax operating loss carryforward	294,171,000	148,338,000
Employee benefits	154,711,000	189,558,000
State tax liability	7,358,000	13,241,000
Accrued expenses	27,645,000	75,407,000
Allowance for doubtful accounts	42,733,000	37,511,000
Other, net	22,313,000	4,238,000
Gross deferred income tax asset	795,645,000	644,872,000
Less: Valuation allowance	(108,662,000)	(115,585,000)
Net deferred income tax asset	686,983,000	529,287,000
Net deferred income tax liability	2,224,722,000	2,074,704,000
Deferred tax assets and liabilities are reflected in the following captions on the consolidated balance sheet [Abstract]
Deferred income taxes	2,458,018,000	2,220,677,000
Income taxes and other current assets	(233,296,000)	(145,973,000)
Net deferred income tax liability	2,224,722,000	2,074,704,000
Federal net operating loss carryforward	503,000,000
State tax operating loss carryforward	1,900,000,000
Current [Abstract]
Federal	(13,320,000)	18,302,000	11,618,000
State	14,252,000	10,260,000	(2,630,000)
Total current	932,000	28,562,000	8,988,000
Deferred [Abstract]
Federal	77,750,000	82,080,000	49,916,000
State	9,661,000	4,357,000	11,024,000
Total deferred	87,411,000	86,437,000	60,940,000
Total income taxes charged to the consolidated statement of operations	88,343,000	114,999,000	69,928,000
Income taxes charged (credited) to shareholders' equity of Frontier [Abstract]
Current benefit arising from stock options exercised and restricted stock	0	0	881,000
Deferred income taxes (benefits) arising from the recognition of additional pension/OPEB liability	(97,409,000)	17,501,000	(4,353,000)
Total income taxes charged (credited) to shareholders' equity of Frontier	(97,409,000)	17,501,000	(3,472,000)
Total income taxes	(9,066,000)	132,500,000	66,456,000
Tax effect of change in method of accounting for repairs and maintenance costs	53,900,000
Gross tax liability for tax positions that may not be sustained under a more likely than not threshold	37,500,000
Additional interest recognized on tax liability	2,100,000
Amount of uncertain tax positions whose statute of limitations are expected to expire during the next twelve months	8,400,000
Unrecognized tax benefits [Roll Forward]
Unrecognized tax benefits - beginning of year	49,180,000	56,860,000
Gross decreases - prior year tax positions	0	(5,442,000)
Gross increases - current year tax positions	8,200,000	1,216,000
Gross decreases - expired statute of limitations	(11,874,000)	(3,454,000)
Unrecognized tax benefits - end of year	33,928,000	49,180,000	56,860,000
Accrued interest on tax liability	$ 3,600,000	$ 5,700,000