Financing Agreements (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	Nov. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 01, 2008	Jun. 16, 2007
Debt Disclosure [Abstract]
Term of loan		20 years
Annual interest rate on loan		1.00%
Initial term no payments of principal or interest due		10 years
Latter term when payments of principal and interest obligaged to be paid		10 years
Term in which lender provided forgiveness of loan at varying amounts		5 years
Threshold amount of loan forgiven up to if certain criteria met, years one through five					$ 5.0
Amount of loan forgiven				5.0
Threshold amount of loan forgiven up to if certain criteria met, year five through ten					4.9
Letter of credit, amount of security for repayment obligations	10.6
Amount of loan outstanding		$ 4.9	$ 4.9		$ 9.9