Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Federal [Abstract]
Current	$ (312,000)	$ 193,000	$ 631,000
Deferred	183,000	347,000	(383,000)
Total Federal Tax Expense	(129,000)	540,000	248,000
State [Abstract]
Current	(1,627,000)	(2,059,000)	(2,028,000)
Deferred (included in Federal above)	0	0	0
Total State Tax Expense	(1,627,000)	(2,059,000)	(2,028,000)
Total	(1,756,000)	(1,519,000)	(1,780,000)
U.S. Federal statutory rate	35.00%
Tax benefit at U.S. statutory rate	640,000	22,945,000	23,545,000
Credits	9,757,000	0	4,803,000
Valuation allowance	(7,097,000)	(24,138,000)	(30,489,000)
Return to provision	(2,568,000)	(225,000)	(1,302,000)
State taxes, net of federal income tax	(985,000)	1,258,000	1,373,000
Officer's compensation	(724,000)	(922,000)	(760,000)
Meals and entertainment	(496,000)	(486,000)	(430,000)
Expired charitable	(126,000)	0	0
Lobbying and Political	(89,000)	0	0
Other, net	(65,000)	122,000	59,000
Unrecognized tax benefits	(3,000)	193,000	630,000
(Loss) gain on acquisition	0	(266,000)	791,000
Deferred income tax assets [Abstract]
Operating loss carryforwards	150,755,000	169,792,000
Accrued expenses	54,400,000	51,124,000
Prepaid revenue	53,228,000	55,386,000
Deferred lease liability	49,864,000	46,541,000
Capital lease obligations	39,748,000	52,720,000
Tax credits	32,673,000	20,551,000
Deferred gain on sale leaseback	8,673,000	10,127,000
Total gross deferred income tax asset	389,341,000	406,241,000
Valuation allowance	(72,366,000)	(65,269,000)
Net deferred income tax assets	316,975,000	340,972,000
Deferred income tax liabilities [Abstract]
Property, plant and equipment	(374,431,000)	(415,354,000)
Other	(6,200,000)	(8,428,000)
Total gross deferred income tax liability	(380,631,000)	(423,782,000)
Net deferred tax liability	(63,656,000)	(82,810,000)
Deferred tax assets (liabilities), Net [Abstract]
Deferred tax asset - current	17,643,000	13,377,000
Deferred tax liability - noncurrent	(81,299,000)	(96,187,000)
Net deferred tax liability	(63,656,000)	(82,810,000)
Operating Loss Carryforwards [Line Items]
Operating loss carry forwards, valuation allowance	44,700,000
Tax Credit Carryforward [Line Items]
Tax credits, valuation allowance	20,600,000	8,500,000
Net operating loss, limitation of utilization	92,000,000
Unrecognized tax benefits [Roll Forward]
Balance at beginning of period	1,245,000
Additions for tax positions related to the current year	53,000
Additions for tax positions related to prior years	414,000
Reductions for tax positions related to prior years	(156,000)
Balance at end of period	1,556,000	1,245,000
Total interest and penalties reserved	600,000
Federal [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carry-forwards	427,400,000	454,600,000
Operating loss carry forwards, valuation allowance	(4,851,000)	26,589,000	22,940,000
Tax Credit Carryforward [Line Items]
Tax credits, valuation allowance	12,123,000	400,000	6,408,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carry forwards, valuation allowance	7,000,000	7,200,000
Restricted Stock [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carry-forwards	$ 53,500,000	$ 31,900,000