Significant Accounting Policies - New Accounting Pronouncements and Changes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, net	$ 725.4				$ 540.3				$ 725.4	$ 540.3
Inventories, net	651.0				634.7				651.0	634.7
Other current assets	69.1				39.6				69.1	39.6
TOTAL ASSETS	4,872.1				3,720.6				4,872.1	3,720.6	$ 3,525.0
Other accrued liabilities	226.6				174.9				226.6	174.9
TOTAL LIABILITIES	3,073.2				2,072.7				3,073.2	2,072.7
Retained earnings	2,064.4				1,892.4				2,064.4	1,892.4
Net sales	1,144.1	$ 1,179.7	$ 1,166.7	$ 991.2	917.7	$ 950.5	$ 948.3	$ 852.3	4,481.7	3,668.8	3,505.2
Cost of goods sold	(823.5)	(830.7)	(818.8)	(708.3)	(628.3)	(642.9)	(652.8)	(589.7)	(3,181.3)	(2,513.7)	(2,400.1)
Selling & administrative expenses	(184.0)	(185.2)	(191.0)	(183.3)	(162.9)	(157.5)	(161.1)	(154.8)	(743.5)	(636.3)	(615.3)
Operating Income									556.9	518.8	489.8
Net income	88.0	$ 113.6	$ 100.3	$ 58.3	20.4	80.8	79.1	62.8	360.2	243.1	293.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,798.9				1,647.9				1,798.9	1,647.9
Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of goods sold					(0.9)	(0.8)	(0.8)	(0.8)		(3.3)	(4.4)
Selling & administrative expenses					(2.9)	(3.0)	(3.0)	(2.9)		(11.8)	(7.6)
Total operating expenses					(3.8)	(3.8)	(3.8)	(3.7)		(15.1)	(12.0)
Operating Income					3.8	3.8	3.8	3.7		15.1	12.0
Total other expense					(3.8)	(3.8)	(3.8)	(3.7)		(15.1)	(12.0)
Net income					0.0	$ 0.0	$ 0.0	$ 0.0		0.0	$ 0.0
Balances Without Adoption of ASC 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, net	708.7								708.7
Inventories, net	661.8								661.8
Other current assets	59.5								59.5
TOTAL ASSETS	4,856.6								4,856.6
Other accrued liabilities	211.7								211.7
TOTAL LIABILITIES	3,058.3								3,058.3
Retained earnings	2,063.8								2,063.8
Net sales									4,478.7
Cost of goods sold									(3,178.3)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,798.3								1,798.3
Effect of Adoption Higher/(Lower) | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, net	16.7								16.7
Inventories, net	(10.8)								(10.8)
Other current assets	9.6								9.6
TOTAL ASSETS	15.5								15.5
Other accrued liabilities	14.9								14.9
TOTAL LIABILITIES	14.9								14.9
Retained earnings	0.6				$ (0.6)				0.6	$ (0.6)
Net sales									3.0
Cost of goods sold									(3.0)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 0.6								$ 0.6