Statements of Consolidated Income - USD ($) shares in Thousands, $ 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
Income Statement [Abstract]
Revenues		$ 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 Goods and Services Sold		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]
Costs and expenses:
Lower of cost or market inventory write-down										0.0		0.0		4.9
Depreciation and amortization										43.9		39.7		36.0
Selling, general, administrative, research and development	[2]									96.3		97.5		105.0
Goodwill impairment								18.4		0.0		18.4		0.0
Other operating charges, net										1.4		0.8		2.8
Total costs and expenses										1,442.3		1,242.3		1,149.5
Operating income		36.9	34.9	34.7	37.1	41.9	41.5	12.5	59.3	143.6		155.2		181.1
Other expense:
Interest expense										(22.7)		(22.2)		(20.3)
Other expense, net – Note 12										(0.9)		0.0		(13.6)
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
Net income per common share:
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
Weighted-average number of common shares outstanding (in thousands):
Basic (in shares)										16,585		16,996		17,813
Diluted (in shares)										16,874		17,259		18,033
Dividends declared per common share (in dollars per share)		$ 0.55	$ 0.55	$ 0.55	$ 0.55	$ 0.50	$ 0.50	$ 0.50	$ 0.50	$ 2.20		$ 2.00		$ 1.80

[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 1 for discussion of our adoption of ASU 2017-07 (as defined in Note 1) and the related reclassification of amounts previously presented in the Statements of Consolidated Income within Selling, general, administrative, research and development and now included within Other expense, net.