Fair Value Measurements (Assets and Liabilities on a Nonrecurring Basis) (Details) - Nonrecurring [Member] - Level 3 [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Certain direct investments in privately-held companies, carrying value	$ 1.3
Certain direct investments in privately-held companies, fair value	0.0
Other (Expense) Income, Net [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment charge	$ 1.3	$ 0.0