Fair Value Measurements, Assets and Liabilities Measured On A Nonrecurring Basis (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other than temporary impairment of privately held equity investments						$ 1.1	$ 2.8
Impairment of goodwill	$ (850.0)	$ 0.0	$ 0.0	$ 0.0	$ 0.0	(850.0)	0.0
Security [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill	(850.0)					(850.0)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value promissory note					132.9
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term and long-term debt, fair value	1,395.2				1,946.7	1,395.2
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability measured at non-recurring basis	$ 0.0				$ 0.0	$ 0.0	0.0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Cost Method Investment, Privately Held Companies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held investments measured on nonrecurring basis							2.0
Other than temporary impairment of privately held equity investments							$ 2.8