Fair Value Measurements, Assets and Liabilities Measured On A Nonrecurring Basis (Details) (Fair Value, Measurements, Nonrecurring [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Liabilities Measured On Nonrecurring Basis Liabilities	$ 0	$ 0
Cost Method Investee, Privately Held Companies | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss due to impairment of privately held equity investments measured on a non-recurring basis	$ 1.8	$ 0	$ 5.5