Financing (Short-Term Debt) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Short-term Debt [Line Items]
Long-term debt	$ 940.3	$ 942.3
Short-term borrowings and current maturities of long-term debt	7.8	6.9
Syndicated Loan Facility [Member]
Short-term Debt [Line Items]
Long-term debt	71.9	76.1
Short-term borrowings and current maturities of long-term debt	6.1	5.3
Building Loan Facility [Member]
Short-term Debt [Line Items]
Long-term debt	26.8	25.1
Short-term borrowings and current maturities of long-term debt	1.7	$ 1.6
Commercial Paper [Member] | CP Program [Member]
Short-term Debt [Line Items]
Short-term borrowings and current maturities of long-term debt	$ 0.0