Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Taxes
Deferred tax valuation allowance	$ (11,600,000)	$ 16,600,000	$ 32,700,000
Balance of deferred tax valuation allowance	258,867,000	270,451,000
Tax credit carryforwards	768,000
Other remaining carryforwards	289,000
Overall effective income tax expense (benefit) rate (as a percent)	3.80%	(5.30%)	0.20%
Tax adjustments, settlements and unusual provisions		2,400,000
Federal
Income Taxes
Deferred tax valuation allowance	(10,500,000)	15,200,000	30,000,000
Period of net operating losses carryforward	20 years
Period of federal tax credit carryforwards	5 years
Period of other remaining tax carryforwards	20 years
State
Income Taxes
Deferred tax valuation allowance	(1,100,000)	1,400,000	2,700,000
Settlement payment with taxing authority		$ 1,600,000
State | Minimum
Income Taxes
Period of net operating losses carryforward	10 years
State | Maximum
Income Taxes
Period of net operating losses carryforward	20 years