Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current:
Federal	$ (136,000)
State	(866,000)	(803,000)	(815,000)
Total	(1,002,000)	(803,000)	(815,000)
Deferred:
Federal	(2,520,000)	4,737,000	(579,000)
State	31,000	159,000	(76,000)
Total	(2,489,000)	4,896,000	(655,000)
Total income tax (expense) benefit	(3,491,000)	4,093,000	(1,470,000)
Reconciliation of the effective income tax rate with the applicable statutory federal income tax rate
Federal tax at statutory rate (as a percent)	35.00%	35.00%	35.00%
State taxes, net of federal benefit (as a percent)	6.90%	3.40%	10.80%
Valuation allowance (as a percent)	(0.40%)	(6.40%)	14.90%
Non-deductible stock based compensation (as a percent)	1.60%		6.50%
Other (as a percent)	0.20%	(1.00%)	0.20%
Effective income tax rate (as a percent)	43.30%	31.00%	67.40%
Deferred income tax assets:
Accruals not currently deductible for income taxes	2,429,000	2,322,000
Net operating loss carry-forwards	13,947,000	16,477,000
Total deferred income tax assets	16,376,000	18,799,000
Deferred income tax liabilities:
Depreciation	(20,739,000)	(20,812,000)
Total	(20,739,000)	(20,812,000)
Valuation allowance	(12,165,000)	(12,189,000)
Net deferred income tax liability	(16,528,000)	(14,202,000)
Amounts recognized in the consolidated balance sheets:
Current deferred income tax assets	78,000	67,000
Noncurrent deferred income tax assets	490,000	496,000
Noncurrent deferred income tax liabilities	(17,096,000)	(14,765,000)
Net deferred income tax liability	$ (16,528,000)	$ (14,202,000)