Stockholders' Equity Stock issuance (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock Issued During Period, Shares, New Issues	605,798	4,981,305
Stock-based compensation related to stock plans	$ 8.4	$ 7.8	$ 8.8
Chief Executive Officer [Member] | Restricted Stock [Member]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 1.1
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	3.3