Summary of Significant Accounting Policies (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012
Net operating loss and tax credit carryforwards
Unrecognized tax benefits	$ 2.8		$ 2.9
Unrecognized tax benefits, if recognized, would not impact the company's effective tax rate	2.7		2.8
Federal
Net operating loss and tax credit carryforwards
Operating loss carryforwards utilized	190.9	26.3
Net operating loss carryforwards			41.4
Research and development and other credit carryforwards			4.9
State
Net operating loss and tax credit carryforwards
Net operating loss carryforwards			34.4
Research and development and other credit carryforwards			4.6
Federal and State | Stock options
Net operating loss and tax credit carryforwards
Net operating loss carryforwards			$ 12.1