Guarantor and Non-Guarantor Financial Statements, Comprehensive Income Statements (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales	$ 367.2	$ 344.1	$ 738.9	$ 679.2
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	294.8	275.5	597.1	558.4
Unrealized losses (gains) on derivative instruments	1.5	(1.6)	6.0	(3.6)
Depreciation and amortization	8.1	7.7	16.1	15.1
Selling, general, administrative, research and development	23.6	22.0	46.3	42.3
Net periodic postretirement benefit cost relating to Salaried VEBA	0.6	(6.1)	1.2	(11.7)
Loss on removal of Union VEBA net assets	1.6		493.8	0.0
Total selling, general, administrative, research and development	25.8	15.9	541.3	30.6
Total costs and expenses	330.2	297.7	1,160.5	600.7
Other operating charges, net		0.2		0.2
Operating (loss) income	37.0	46.4	(421.6)	78.5
Other (expense) income:
Interest expense	(5.2)	(9.2)	(15.0)	(18.0)
Other income, net	0.4	1.8	0.8	3.7
(Loss) income before income taxes	32.2	39.0	(435.8)	64.2
Income tax (provision) benefit	(12.0)	(14.5)	163.8	(23.9)
Earnings in equity of subsidiaries	0.0	0.0	0.0	0.0
Net income	20.2	24.5	(272.0)	40.3
Comprehensive income	20.6	26.6	(204.7)	43.3
Parent
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales	0.0	0.0	0.0	0.0
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	0.0	0.0	0.0	0.0
Unrealized losses (gains) on derivative instruments	0.0	0.0	0.0	0.0
Depreciation and amortization	0.0	0.0	0.0	0.0
Selling, general, administrative, research and development	1.4	1.2	2.4	2.2
Net periodic postretirement benefit cost relating to Salaried VEBA	0.0	0.0	0.0	0.0
Loss on removal of Union VEBA net assets	0.0		0.0
Total selling, general, administrative, research and development	1.4	1.2	2.4	2.2
Total costs and expenses	1.4	1.2	2.4	2.2
Other operating charges, net		0.0		0.0
Operating (loss) income	(1.4)	(1.2)	(2.4)	(2.2)
Other (expense) income:
Interest expense	(4.9)	(9.3)	(14.4)	(18.6)
Other income, net	0.0	0.4	0.0	1.4
(Loss) income before income taxes	(6.3)	(10.1)	(16.8)	(19.4)
Income tax (provision) benefit	0.0	0.0	0.0	0.0
Earnings in equity of subsidiaries	26.5	34.6	(255.2)	59.7
Net income	20.2	24.5	(272.0)	40.3
Comprehensive income	20.6	26.6	(204.7)	43.3
Guarantor Subsidiaries
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales	358.3	335.7	721.7	662.8
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	289.4	270.8	585.8	549.7
Unrealized losses (gains) on derivative instruments	1.5	(1.6)	6.0	(3.6)
Depreciation and amortization	7.8	7.5	15.5	14.6
Selling, general, administrative, research and development	19.5	18.5	40.2	35.1
Net periodic postretirement benefit cost relating to Salaried VEBA	0.6	(6.1)	1.2	(11.7)
Loss on removal of Union VEBA net assets	1.6		493.8
Total selling, general, administrative, research and development	21.7	12.4	535.2	23.4
Total costs and expenses	320.4	289.3	1,142.5	584.3
Other operating charges, net		0.2		0.2
Operating (loss) income	37.9	46.4	(420.8)	78.5
Other (expense) income:
Interest expense	(0.3)	0.0	(0.8)	0.4
Other income, net	0.3	0.8	0.8	2.0
(Loss) income before income taxes	37.9	47.2	(420.8)	80.9
Income tax (provision) benefit	(15.8)	(17.8)	156.1	(30.4)
Earnings in equity of subsidiaries	2.1	1.4	3.2	1.8
Net income	24.2	30.8	(261.5)	52.3
Comprehensive income	24.6	33.0	(194.3)	55.2
Non-Guarantor Subsidiaries
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales	33.5	34.0	68.2	67.1
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	28.9	29.7	60.5	58.1
Unrealized losses (gains) on derivative instruments	0.0	0.0	0.0	0.0
Depreciation and amortization	0.3	0.2	0.6	0.5
Selling, general, administrative, research and development	3.2	2.9	4.8	6.2
Net periodic postretirement benefit cost relating to Salaried VEBA	0.0	0.0	0.0	0.0
Loss on removal of Union VEBA net assets	0.0		0.0
Total selling, general, administrative, research and development	3.2	2.9	4.8	6.2
Total costs and expenses	32.4	32.8	65.9	64.8
Other operating charges, net		0.0		0.0
Operating (loss) income	1.1	1.2	2.3	2.3
Other (expense) income:
Interest expense	0.0	0.0	0.0	0.0
Other income, net	0.1	0.7	0.2	0.5
(Loss) income before income taxes	1.2	1.9	2.5	2.8
Income tax (provision) benefit	1.4	(0.5)	1.4	(0.8)
Earnings in equity of subsidiaries	0.0	0.0	0.0	0.0
Net income	2.6	1.4	3.9	2.0
Comprehensive income	2.6	1.3	4.0	2.1
Consolidating Adjustments
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales	(24.6)	(25.6)	(51.0)	(50.7)
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	(23.5)	(25.0)	(49.2)	(49.4)
Unrealized losses (gains) on derivative instruments	0.0	0.0	0.0	0.0
Depreciation and amortization	0.0	0.0	0.0	0.0
Selling, general, administrative, research and development	(0.5)	(0.6)	(1.1)	(1.2)
Net periodic postretirement benefit cost relating to Salaried VEBA	0.0	0.0	0.0	0.0
Loss on removal of Union VEBA net assets	0.0		0.0
Total selling, general, administrative, research and development	(0.5)	(0.6)	(1.1)	(1.2)
Total costs and expenses	(24.0)	(25.6)	(50.3)	(50.6)
Other operating charges, net		0.0		0.0
Operating (loss) income	(0.6)	0.0	(0.7)	(0.1)
Other (expense) income:
Interest expense	0.0	0.1	0.2	0.2
Other income, net	0.0	(0.1)	(0.2)	(0.2)
(Loss) income before income taxes	(0.6)	0.0	(0.7)	(0.1)
Income tax (provision) benefit	2.4	3.8	6.3	7.3
Earnings in equity of subsidiaries	(28.6)	(36.0)	252.0	(61.5)
Net income	(26.8)	(32.2)	257.6	(54.3)
Comprehensive income	$ (27.2)	$ (34.3)	$ 190.3	$ (57.3)