Reportable Business Segments (Geographic Information) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total net sales to external customers	$ 891.8	$ 1,052.3	$ 1,102.1	$ 793.4	$ 897.3	$ 1,010.0	$ 1,019.2	$ 715.2	$ 3,839.6	$ 3,641.6	$ 3,467.4
Total property, plant and equipment, net	397.8				361.4				397.8	361.4	339.6
United States [Member]
Segment Reporting Information [Line Items]
Total net sales to external customers									3,128.7	2,966.8	2,793.4
Total property, plant and equipment, net	257.6				237.6				257.6	237.6	224.8
Mexico [Member]
Segment Reporting Information [Line Items]
Total property, plant and equipment, net	79.8				69.4				79.8	69.4	60.0
Canada [Member]
Segment Reporting Information [Line Items]
Total net sales to external customers									237.8	218.8	217.7
Total property, plant and equipment, net	1.7				1.4				1.7	1.4	1.2
International [Member]
Segment Reporting Information [Line Items]
Total net sales to external customers									473.1	456.0	456.3
Total property, plant and equipment, net	$ 58.7				$ 53.0				$ 58.7	$ 53.0	$ 53.6