Supplemental Cash Flows Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Noncash or Part Noncash Divestitures [Line Items]
Interest Paid, Including Capitalized Interest, Operating and Investing Activities	$ 54.0	$ 35.8	$ 33.1
Cash paid for income taxes	37.6	51.1	37.4
Capital Expenditures Incurred but Not yet Paid	0.4	0.3	0.4
Tax Benefit from Stock Options Exercised	$ 3.3	2.9	$ 5.4
Tea Leaves [Member] | Digital Media
Noncash or Part Noncash Divestitures [Line Items]
Noncash or Part Noncash Divestiture, Amount of Consideration Received		$ 57.7