Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowances for doubtful accounts receivable:
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 4.7	$ 4.7	$ 3.4
Additions / (Reversals) Charged to Costs and Expenses	1.5	0.8	2.7
Deductions	(3.5)	(0.8)	(1.4)
Acquisitions	1.9	0.0	0.0
Balance at End of Year	4.6	4.7	4.7
Allowance for credit memos, returns and cash discounts:
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	45.9	41.5	36.7
Additions / (Reversals) Charged to Costs and Expenses	260.8	249.2	233.2
Deductions	(256.3)	(244.8)	(228.4)
Acquisitions	0.1	0.0	0.0
Balance at End of Year	50.5	45.9	41.5
Valuation allowance on deferred tax assets:
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	22.6	22.0	34.3
Additions / (Reversals) Charged to Costs and Expenses	(3.2)	0.6	(12.3)
Deductions	0.0	0.0	0.0
Acquisitions	0.0	0.0	0.0
Balance at End of Year	$ 19.4	$ 22.6	$ 22.0