Derivative Instruments and Hedging Activities Hedging Activities (Details) $ in Millions	Sep. 30, 2018 USD ($)
Current portion of long-term debt and short-term borrowings
Derivative [Line Items]
Carrying amount of the hedged assets/liabilities	$ 0.0
Cumulative amount of fair value hedging adjustment(s) in the hedged assets/liabilities(1) Increase/(Decrease)	(0.6)
Long-term debt
Derivative [Line Items]
Carrying amount of the hedged assets/liabilities	0.0
Cumulative amount of fair value hedging adjustment(s) in the hedged assets/liabilities(1) Increase/(Decrease)	$ 8.8