Financial Instruments and Risk Management (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Mar. 31, 2012 USD ($) derivative_instrument
Derivative [Line Items]
Total exposure to floating rate interest rates	0.00%	1.00%
Number of interest rate derivatives terminated | derivative_instrument				2
Loss on extinguishment of debt	$ (11.6)	$ (0.7)	$ 0.0
Loss written-off resulting from non-performance of counterparties	5.6
March 2012 Interest-Rate Swap Termination
Derivative [Line Items]
Notional amount related to discontinuation of interest rate fair value hedge				$ 350.0
Unrealized gains on interest-rate swap agreements				$ 46.1
Amortization of deferred hedge gains	0.0	6.0
Loss on extinguishment of debt		3.6
Foreign Exchange Contract
Derivative [Line Items]
Notional amounts of derivative contracts	816.0
Gain (loss) in other expense from undesignated foreign currency exchange contracts	42.1	$ 2.6
Foreign Exchange Contract | Cash Flow Hedging
Derivative [Line Items]
Notional amounts of derivative contracts	$ 3.7