Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Federal [Abstract]
Current	$ 631,000	$ 626,000	$ 2,795,000
Deferred	(943,000)	33,235,000	31,684,000
Total Federal Tax Expense	(312,000)	33,861,000	34,479,000
State [Abstract]
Current	(2,028,000)	(2,429,000)	(1,553,000)
Deferred (included in Federal above)	0	0	0
Total State Tax Expense	(2,028,000)	(2,429,000)	(1,553,000)
Total	(2,340,000)	31,432,000	32,926,000
U.S. Federal statutory rate (in hundredths)	35.00%	35.00%	35.00%
Tax benefit at U.S. statutory rate	23,042,000	28,117,000	34,713,000
Credits	4,803,000	3,354,000	2,088,000
State taxes, net of federal income tax	1,316,000	1,634,000	3,002,000
Gain on acquisition	791,000
Unrecognized tax benefits	630,000	626,000	1,892,000
Other, net	59,000	(124,000)	(75,000)
Officer's compensation	(760,000)	(2,197,000)	(2,147,000)
Stock compensation		(137,000)	(5,550,000)
Return to provision	(1,302,000)	679,000	241,000
Valuation allowance	(30,489,000)	(137,000)	(973,000)
Meals and Entertainment	(430,000)	(383,000)	(265,000)
Deferred income tax assets [Abstract]
Operating loss carryforwards	174,433,000	165,617,000
Capital lease obligations	62,136,000	70,407,000
Prepaid revenue	48,587,000	48,713,000
Accrued expenses	40,422,000	46,111,000
Deferred lease liability	48,916,000	44,097,000
Tax credits	20,158,000	13,548,000
Deferred gain on sale leaseback	11,581,000	13,035,000
Fair value of interest rate swaps	152,000
Total gross deferred income tax asset	406,385,000	401,528,000
Valuation allowance	(40,820,000)	(10,845,000)
Net deferred income tax assets	365,565,000	390,683,000
Deferred income tax liabilities [Abstract]
Property, plant and equipment	(454,985,000)	(478,023,000)
Fair value of interest rate swaps		(516,000)
Other	(11,540,000)	(10,571,000)
Total gross deferred income tax liability	(466,525,000)	(489,110,000)
Net deferred tax liability	(100,960,000)	(98,427,000)
Deferred tax assets (liabilities), Net [Abstract]
Deferred tax asset - current	11,776,000	15,529,000
Deferred tax liability - noncurrent	(112,736,000)	(113,956,000)
Net deferred tax liability	(100,960,000)	(98,427,000)
Operating Loss Carryforwards [Line Items]
Net operating loss carry-forwards	461,500,000	427,800,000
Unrecognized tax benefits [Roll Forward]
Balance at beginning of period	1,597,000
Additions for tax positions related to the current year	76,000
Additions for tax positions related to prior years	244,000
Reductions for tax positions related to prior years	(478,000)
Balance at end of period	1,439,000	1,597,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carry forwards, valuation allowance	9,700,000	8,600,000
Federal and State [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carry forwards, valuation allowance	23,000,000
Tax Credit Carryforward [Line Items]
Tax credits, valuation allowance	8,100,000	2,200,000
Net operating loss, limitation of utilization	92,000,000
Total interest and penalties reserved	500,000
Restricted Stock [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carry-forwards	$ 26,900,000	$ 15,200,000