Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Net sales	$ 2,189.1	$ 1,973.3	$ 2,004.3
Cost of sales	1,608.3	1,421.5	1,439.7
Gross margin	580.8	551.8	564.6
Selling, general and administrative expenses	146.0	151.8	157.6
Research and technology expenses	55.9	49.4	46.9
Other operating expense	7.7
Operating income	371.2	350.6	360.1
Interest expense, net	37.7	27.4	22.1
Non-operating expense			0.4
Income before income taxes, and equity in earnings of affiliated companies	333.5	323.2	337.6
Provision for income taxes	62.5	42.5	90.3
Income before equity in earnings of affiliated companies	271.0	280.7	247.3
Equity in earnings from affiliated companies	5.6	3.3	2.5
Net income	$ 276.6	$ 284.0	$ 249.8
Basic net income per common share:	$ 3.15	$ 3.13	$ 2.69
Diluted net income per common share:	$ 3.11	$ 3.09	$ 2.65
Weighted-average common shares:
Basic	87.9	90.6	92.8
Diluted	89.0	91.9	94.2