Guarantor Condensed Consolidating Financial Statements - Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Condensed Financial Statements, Captions [Line Items]
Parent's ownership percentage	100.00%		100.00%
Net Sales	$ 1,137.6	$ 1,103.7	$ 3,293.8	$ 3,240.9
Cost of Sales	946.0	912.4	2,750.3	2,637.1
Selling, General and Administrative	90.6	78.9	265.3	260.7
Other (Income) Expense, Net	2.0	(0.1)	1.4	2.0
Business Combinations and Shutdown and Other Special Charges	3.6	7.4	18.3	23.2
Income (Loss) from Operations	95.4	105.1	258.5	317.9
Interest Expense, Net	(22.6)	(20.0)	(66.4)	(55.1)
Income (Loss) before Income Taxes and Equity Income of Unconsolidated Entity	72.8	85.1	192.1	262.8
Income Tax (Expense) Benefit	(25.9)	(28.0)	(67.1)	(71.3)
Income (Loss) before Equity Income of Unconsolidated Entities	46.9	57.1	125.0	191.5
Equity Income of Unconsolidated Entity	0.4	0.7	1.3	1.6
Equity in Net Earnings of Subsidiaries	0.0	0.0	0.0	0.0
Net Income (Loss)	47.3	57.8	126.3	193.1
Comprehensive Income (Loss)	58.2	58.3	170.9	156.4
Reportable Legal Entities | Parent
Condensed Financial Statements, Captions [Line Items]
Net Sales	0.0	0.0	0.0	0.0
Cost of Sales	0.0	0.0	0.0	0.0
Selling, General and Administrative	0.0	0.0	0.0	0.0
Other (Income) Expense, Net	0.0	0.0	0.0	0.0
Business Combinations and Shutdown and Other Special Charges	0.0	0.0	0.0	0.0
Income (Loss) from Operations	0.0	0.0	0.0	0.0
Interest Expense, Net	0.0	0.0	0.0	0.0
Income (Loss) before Income Taxes and Equity Income of Unconsolidated Entity	0.0	0.0	0.0	0.0
Income Tax (Expense) Benefit	0.0	0.0	0.0	0.0
Income (Loss) before Equity Income of Unconsolidated Entities	0.0	0.0	0.0	0.0
Equity Income of Unconsolidated Entity	0.0	0.0	0.0	0.0
Equity in Net Earnings of Subsidiaries	47.3	57.8	126.3	193.1
Net Income (Loss)	47.3	57.8	126.3	193.1
Comprehensive Income (Loss)	58.2	58.3	170.9	156.4
Reportable Legal Entities | Subsidiary Issuer
Condensed Financial Statements, Captions [Line Items]
Net Sales	911.0	872.6	2,646.1	2,612.8
Cost of Sales	756.4	715.9	2,206.4	2,117.0
Selling, General and Administrative	68.8	53.6	200.8	193.1
Other (Income) Expense, Net	(0.6)	(1.5)	(5.9)	(4.1)
Business Combinations and Shutdown and Other Special Charges	2.5	7.1	10.6	21.6
Income (Loss) from Operations	83.9	97.5	234.2	285.2
Interest Expense, Net	(21.5)	(19.0)	(63.2)	(52.1)
Income (Loss) before Income Taxes and Equity Income of Unconsolidated Entity	62.4	78.5	171.0	233.1
Income Tax (Expense) Benefit	(20.8)	(24.6)	(57.5)	(60.7)
Income (Loss) before Equity Income of Unconsolidated Entities	41.6	53.9	113.5	172.4
Equity Income of Unconsolidated Entity	0.0	0.0	0.0	0.0
Equity in Net Earnings of Subsidiaries	5.7	3.9	12.8	20.7
Net Income (Loss)	47.3	57.8	126.3	193.1
Comprehensive Income (Loss)	58.2	58.3	170.9	156.4
Reportable Legal Entities | Combined Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net Sales	0.6	27.1	50.1	72.4
Cost of Sales	(0.3)	23.6	41.0	61.5
Selling, General and Administrative	0.0	4.5	3.5	8.2
Other (Income) Expense, Net	0.0	0.0	0.1	0.0
Business Combinations and Shutdown and Other Special Charges	0.0	0.0	0.0	0.0
Income (Loss) from Operations	0.9	(1.0)	5.5	2.7
Interest Expense, Net	0.0	0.0	0.0	0.0
Income (Loss) before Income Taxes and Equity Income of Unconsolidated Entity	0.9	(1.0)	5.5	2.7
Income Tax (Expense) Benefit	(1.5)	0.7	(3.2)	(1.0)
Income (Loss) before Equity Income of Unconsolidated Entities	(0.6)	(0.3)	2.3	1.7
Equity Income of Unconsolidated Entity	0.0	0.0	0.0	0.0
Equity in Net Earnings of Subsidiaries	(0.8)	0.9	(5.3)	(2.6)
Net Income (Loss)	(1.4)	0.6	(3.0)	(0.9)
Comprehensive Income (Loss)	(1.5)	(0.7)	(23.5)	(4.1)
Reportable Legal Entities | Combined Nonguarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net Sales	308.7	281.2	843.3	783.9
Cost of Sales	272.6	250.1	748.6	686.8
Selling, General and Administrative	21.8	20.8	61.0	59.4
Other (Income) Expense, Net	2.6	1.4	7.2	6.1
Business Combinations and Shutdown and Other Special Charges	1.1	0.3	7.7	1.6
Income (Loss) from Operations	10.6	8.6	18.8	30.0
Interest Expense, Net	(1.1)	(1.0)	(3.2)	(3.0)
Income (Loss) before Income Taxes and Equity Income of Unconsolidated Entity	9.5	7.6	15.6	27.0
Income Tax (Expense) Benefit	(3.6)	(4.1)	(6.4)	(9.6)
Income (Loss) before Equity Income of Unconsolidated Entities	5.9	3.5	9.2	17.4
Equity Income of Unconsolidated Entity	0.4	0.7	1.3	1.6
Equity in Net Earnings of Subsidiaries	0.0	0.0	0.0	0.0
Net Income (Loss)	6.3	4.2	10.5	19.0
Comprehensive Income (Loss)	24.6	(3.8)	69.8	(22.0)
Consolidating Eliminations
Condensed Financial Statements, Captions [Line Items]
Net Sales	(82.7)	(77.2)	(245.7)	(228.2)
Cost of Sales	(82.7)	(77.2)	(245.7)	(228.2)
Selling, General and Administrative	0.0	0.0	0.0	0.0
Other (Income) Expense, Net	0.0	0.0	0.0	0.0
Business Combinations and Shutdown and Other Special Charges	0.0	0.0	0.0	0.0
Income (Loss) from Operations	0.0	0.0	0.0	0.0
Interest Expense, Net	0.0	0.0	0.0	0.0
Income (Loss) before Income Taxes and Equity Income of Unconsolidated Entity	0.0	0.0	0.0	0.0
Income Tax (Expense) Benefit	0.0	0.0	0.0	0.0
Income (Loss) before Equity Income of Unconsolidated Entities	0.0	0.0	0.0	0.0
Equity Income of Unconsolidated Entity	0.0	0.0	0.0	0.0
Equity in Net Earnings of Subsidiaries	(52.2)	(62.6)	(133.8)	(211.2)
Net Income (Loss)	(52.2)	(62.6)	(133.8)	(211.2)
Comprehensive Income (Loss)	$ (81.3)	$ (53.8)	$ (217.2)	$ (130.3)