Income Taxes (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Income Taxes
Balance of deferred tax valuation allowance	$ 268,100,000		$ 268,100,000		$ 270,500,000
Deferred tax valuation allowance	(4,400,000)
Overall effective income tax expense (benefit) rate (as a percent)	2.90%	0.00%	14.00%	(7.30%)
Tax expense (benefit)	$ 190,000	$ 0	$ 190,000	$ (2,398,000)
Federal
Income Taxes
Net operating losses carryforward			20 years
Period of federal tax credit carryforwards			5 years
State | Minimum
Income Taxes
Net operating losses carryforward			10 years
State | Maximum
Income Taxes
Net operating losses carryforward			20 years