Reportable Business Segments (Geographic Information) (Details) - USD ($) $ 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
Segment Reporting Information [Line Items]
Net sales	$ 843.6	$ 1,030.2	$ 1,175.4	$ 834.8	$ 891.8	$ 1,052.3	$ 1,102.1	$ 793.4	$ 3,883.9	$ 3,839.6	$ 3,641.6
Total property, plant and equipment, net	408.3				397.8				408.3	397.8	361.4
UNITED STATES
Segment Reporting Information [Line Items]
Net sales									3,275.9	3,128.7	2,966.8
Total property, plant and equipment, net	293.3				257.6				293.3	257.6	237.6
Mexico [Member]
Segment Reporting Information [Line Items]
Total property, plant and equipment, net	86.7				79.8				86.7	79.8	69.4
CANADA
Segment Reporting Information [Line Items]
Net sales									254.8	237.8	218.8
Total property, plant and equipment, net	1.7				1.7				1.7	1.7	1.4
International [Member]
Segment Reporting Information [Line Items]
Net sales									353.2	473.1	456.0
Total property, plant and equipment, net	$ 26.6				$ 58.7				$ 26.6	$ 58.7	$ 53.0