Revenue Recognition Standard (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended								12 Months Ended
		Jan. 01, 2018	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]
Effect of LIFO Inventory Liquidation on Income		$ 5.0
Contract assets		55.6	$ 54.9				$ 0.0				$ 54.9		$ 0.0
Inventories		167.2	215.1				207.9				215.1		207.9
Total current assets		671.5	656.6				656.6				656.6		656.6
Deferred tax assets, net		68.7	35.9				72.0				35.9		72.0
Total assets		1,396.8	1,419.3				1,385.2				1,419.3		1,385.2
Other accrued liabilities		42.0	44.0				40.5				44.0		40.5
Total current liabilities		174.6	205.5				173.1				205.5		173.1
Total liabilities		640.4	678.9				638.9				678.9		638.9
Retained earnings		95.6	150.2				85.5				150.2		85.5
Total stockholders' equity		756.4	740.4				746.3				740.4		746.3
Total liabilities and stockholders' equity		1,396.8	1,419.3				1,385.2				1,419.3		1,385.2
Net sales			389.4	$ 393.1	$ 415.4	$ 388.0	353.1	$ 332.8	$ 356.3	$ 355.3	1,585.9		1,397.5		$ 1,330.6
Cost of products sold, excluding depreciation and amortization and other items			317.3	323.3	343.4	316.7	277.2	256.4	289.6	262.7	1,300.7	[1]	1,085.9	[1]	1,000.8	[1]
Operating income			36.9	34.9	34.7	37.1	41.9	41.5	12.5	59.3	143.6		155.2		181.1
Income before income taxes											120.0		133.0		147.2
Income tax provision											(28.3)		(87.6)		(55.5)
Net income			$ 23.6	$ 21.7	$ 20.7	$ 25.7	$ (15.2)	$ 19.9	$ 4.7	$ 36.0	$ 91.7		$ 45.4		$ 91.7
Basic (in dollars per share)			$ 1.44	$ 1.31	$ 1.24	$ 1.54	$ (0.90)	$ 1.18	$ 0.28	$ 2.07	$ 5.53		$ 2.67		$ 5.15
Diluted (in dollars per share)			$ 1.41	$ 1.29	$ 1.22	$ 1.51	$ (0.90)	$ 1.16	$ 0.27	$ 2.04	$ 5.43		$ 2.63		$ 5.09
Comprehensive income											$ 80.0		$ 45.4		$ 86.7
Contract assets											0.7		0.0		0.0
Inventories											(45.0)		(6.3)		13.1
Accrued liabilities											(2.6)		(4.7)		26.2
Net cash provided by operating activities	[2]										150.2		141.5		$ 165.6
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract assets			$ 0.0				$ 0.0				0.0		0.0
Inventories			247.5				207.9				247.5		207.9
Total current assets			634.1				656.6				634.1		656.6
Deferred tax assets, net			39.2				72.0				39.2		72.0
Total assets			1,400.1				1,385.2				1,400.1		1,385.2
Other accrued liabilities			40.3				40.5				40.3		40.5
Total current liabilities			201.8				173.1				201.8		173.1
Total liabilities			675.2				638.9				675.2		638.9
Retained earnings			134.7				85.5				134.7		85.5
Total stockholders' equity			724.9				746.3				724.9		746.3
Total liabilities and stockholders' equity			1,400.1				$ 1,385.2				1,400.1		$ 1,385.2
Net sales											1,587.1
Cost of products sold, excluding depreciation and amortization and other items											1,309.0
Operating income											136.5
Income before income taxes											112.9
Income tax provision											(26.6)
Net income											$ 86.3
Basic (in dollars per share)											$ 5.20
Diluted (in dollars per share)											$ 5.11
Comprehensive income											$ 74.6
Contract assets											0.0
Inventories											(36.7)
Accrued liabilities											(4.8)
Net cash provided by operating activities											150.2
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract assets		55.6	(54.9)								(54.9)
Inventories		(40.7)	32.4								32.4
Total current assets		14.9	(22.5)								(22.5)
Deferred tax assets, net		(3.3)	3.3								3.3
Total assets		11.6	(19.2)								(19.2)
Other accrued liabilities		1.5	(3.7)								(3.7)
Total current liabilities		1.5	(3.7)								(3.7)
Total liabilities		1.5	(3.7)								(3.7)
Retained earnings		10.1	(15.5)								(15.5)
Total stockholders' equity		10.1	(15.5)								(15.5)
Total liabilities and stockholders' equity		$ 11.6	$ (19.2)								(19.2)
Net sales											1.2
Cost of products sold, excluding depreciation and amortization and other items											8.3
Operating income											(7.1)
Income before income taxes											(7.1)
Income tax provision											1.7
Net income											$ (5.4)
Basic (in dollars per share)											$ (0.33)
Diluted (in dollars per share)											$ (0.32)
Comprehensive income											$ (5.4)
Contract assets											(0.7)
Inventories											8.3
Accrued liabilities											(2.2)
Net cash provided by operating activities											$ 0.0

[1] See Note 7 for discussion of our adoption of ASU 2017-12 (as defined in Note 1) and the related reclassification of amounts previously presented in the Statements of Consolidated Income within Unrealized (gain) loss on derivative instruments and now included within Cost of products sold, excluding depreciation and amortization and other items.

[2] See Note 11 for adjustments made to arrive at our Consolidated Balance Sheet as of January 1, 2018 upon adopting ASC 606 (as defined in Note 1).