Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated other comprehensive income (loss), derivatives qualifying as hedges, net of tax	$ (152.9)	$ (264.3)	$ (232.2)	$ (148.2)
Currency derivatives expected to be reclassified into earnings over the next twelve months	0.3
Amount expected to be reclassified into interest expense over the next twelve months	1.0
Interest Rate Swap [Member]
Derivative, Notional Amount	250.0
Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative, Notional Amount	57.7	132.6
Accumulated other comprehensive income (loss), derivatives qualifying as hedges, net of tax	0.3	0.8
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative, Notional Amount	250.0
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Accumulated other comprehensive income (loss), derivatives qualifying as hedges, net of tax	$ 3.5	$ 2.6