Fair Value Measurements Fair Value and Related Carrying Amount of Certain Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 443.8	$ 376.1
Checks outstanding in excess of cash balances	12.3	29.8
Long-term Debt, Gross	2,020.9	2,191.5
Long-term Debt	2,020.9	2,014.7
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	443.8	376.1
Checks outstanding in excess of cash balances	12.3	29.8
Long-term debt	$ 2,104.3	$ 1,784.6