Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net sales	$ 1,973.3	$ 2,004.3	$ 1,861.2
Cost of sales	1,421.5	1,439.7	1,328.4
Gross margin	551.8	564.6	532.8
Selling, general and administrative expenses	151.8	157.6	156.1
Research and technology expenses	49.4	46.9	44.3
Operating income	350.6	360.1	332.4
Interest expense, net	27.4	22.1	14.2
Non-operating expense		0.4
Income before income taxes, and equity in earnings of affiliated companies	323.2	337.6	318.2
Provision for income taxes	42.5	90.3	83.0
Income before equity in earnings of affiliated companies	280.7	247.3	235.2
Equity in earnings from affiliated companies	3.3	2.5	2.0
Net income	$ 284.0	$ 249.8	$ 237.2
Basic net income per common share:	$ 3.13	$ 2.69	$ 2.48
Diluted net income per common share:	$ 3.09	$ 2.65	$ 2.44
Weighted-average common shares:
Basic	90.6	92.8	95.8
Diluted	91.9	94.2	97.2