Income Taxes (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Effective Income Tax Rate
Statutory U.S. Federal income tax rate (as a percent)	(35.00%)	(35.00%)
State income taxes, net of U.S. Federal income tax (as a percent)	(3.10%)	(3.30%)
Permanent items (as a percent)	1.00%	1.20%
Valuation allowance (as a percent)	38.20%	(14.70%)
Other (as a percent)	6.60%	0.10%
Effective income tax rate (as a percent)	7.70%	(51.70%)
Federal
Operating loss carryforwards
Unused federal net operating loss carryforwards	187.4