Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Principles of Consolidation/Depreciation and Amortization) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2007	Dec. 31, 2006
Depreciation and amortization expense relating to intangibles	$ 4.7	$ 1.7	$ 1.4	$ 1.8	$ 1.7	$ 1.5