New Accounting Pronouncements Revenue Recognition (Details) - USD ($) $ in Millions	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Inventories, net	$ 800.2	$ 758.9	$ 766.3
Prepayments and other current assets (including contract assets)	185.1	154.8	145.4
Accounts payable and other accrued expenses (including contract liabilities)		2,270.4
Retained Earnings	$ 4,958.8	4,532.9	4,531.0
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Inventories, net		(7.4)
Prepayments and other current assets (including contract assets)		9.4
Accounts payable and other accrued expenses (including contract liabilities)		0.1
Retained earnings		1.9
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Transferred over Time [Member]
Retained earnings		2.0
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Inventories, net			766.3
Prepayments and other current assets (including contract assets)			145.4
Accounts payable and other accrued expenses (including contract liabilities)			2,270.3
Retained Earnings			$ 4,531.0
Contract with Customer, Variable Consideration [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Retained Earnings		$ 0.1