Financial Information for Subsidiary and Guarantor Parent (B.S.) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
ASSETS
Cash and cash equivalents	$ 250.9	$ 269.5	$ 355.1	$ 1,026.8
Accounts receivable, net	593.4	603.6
Intercompany notes receivable	0.0	0.0
Inventories, net	1,472.9	1,472.8
Prepaid expenses and other current assets	66.3	136.2
Total current assets	2,383.5	2,482.1
Property, plant and equipment, net	2,946.7	2,961.8
Cost in excess of net assets acquired	781.5	780.4
Intercompany notes receivable	0.0	0.0
Investment in subsidiaries	0.0	0.0
Other assets	357.6	358.3
Total assets	6,469.3	6,582.6
LIABILITIES AND EQUITY
Accounts payable	487.5	556.7
Accrued liabilities	314.4	323.2
Intercompany notes payable	0.0	0.0
Deferred income taxes	67.8	62.2
Short-term debt and current portion of long-term debt	18.3	17.8
Total current liabilities	888.0	959.9
Long-term debt	1,502.7	1,509.1
Intercompany notes payable	0.0	0.0
Accrued postretirement benefits	397.1	415.8
Pension liabilities	722.1	739.3
Deferred income taxes	143.6	80.9
Other long-term liabilities	103.0	156.2
Total liabilities	3,756.5	3,861.2
Redeemable noncontrolling interest	12.1	12.1
Total stockholders’ equity	2,700.7	2,709.3	$ 2,978.6	$ 2,994.7
Total Liabilities and Equity	6,469.3	6,582.6
Parent Company
ASSETS
Cash and cash equivalents	5.2	2.2
Accounts receivable, net	0.1	0.1
Intercompany notes receivable	0.0	0.0
Inventories, net	0.0	0.0
Prepaid expenses and other current assets	7.0	63.7
Total current assets	12.3	66.0
Property, plant and equipment, net	2.5	2.2
Cost in excess of net assets acquired	0.0	0.0
Intercompany notes receivable	0.0	0.0
Investment in subsidiaries	6,228.5	6,149.4
Other assets	22.9	23.7
Total assets	6,266.2	6,241.3
LIABILITIES AND EQUITY
Accounts payable	3.4	4.5
Accrued liabilities	42.8	47.5
Intercompany notes payable	1,274.2	1,232.6
Deferred income taxes	67.8	62.2
Short-term debt and current portion of long-term debt	0.7	0.5
Total current liabilities	1,388.9	1,347.3
Long-term debt	1,350.9	1,350.6
Intercompany notes payable	0.0	0.0
Accrued postretirement benefits	0.0	0.0
Pension liabilities	662.0	675.5
Deferred income taxes	143.6	80.9
Other long-term liabilities	20.1	77.7
Total liabilities	3,565.5	3,532.0
Redeemable noncontrolling interest	0.0	0.0
Total stockholders’ equity	2,700.7	2,709.3
Total Liabilities and Equity	6,266.2	6,241.3
Subsidiaries
ASSETS
Cash and cash equivalents	14.9	13.8
Accounts receivable, net	168.0	209.1
Intercompany notes receivable	0.0	0.0
Inventories, net	388.6	387.7
Prepaid expenses and other current assets	9.8	13.2
Total current assets	581.3	623.8
Property, plant and equipment, net	1,549.5	1,545.1
Cost in excess of net assets acquired	126.6	126.6
Intercompany notes receivable	0.0	0.0
Investment in subsidiaries	37.7	37.7
Other assets	30.9	28.0
Total assets	2,326.0	2,361.2
LIABILITIES AND EQUITY
Accounts payable	263.7	302.0
Accrued liabilities	59.8	72.0
Intercompany notes payable	1,241.3	1,158.2
Deferred income taxes	0.0	0.0
Short-term debt and current portion of long-term debt	0.1	0.1
Total current liabilities	1,564.9	1,532.3
Long-term debt	150.2	150.3
Intercompany notes payable	200.0	200.0
Accrued postretirement benefits	147.1	153.0
Pension liabilities	5.7	6.0
Deferred income taxes	0.0	0.0
Other long-term liabilities	21.0	22.5
Total liabilities	2,088.9	2,064.1
Redeemable noncontrolling interest	0.0	0.0
Total stockholders’ equity	237.1	297.1
Total Liabilities and Equity	2,326.0	2,361.2
NonGuarantor Subsidiaries
ASSETS
Cash and cash equivalents	230.8	253.5
Accounts receivable, net	425.3	394.4
Intercompany notes receivable	2,515.5	2,390.8
Inventories, net	1,084.3	1,085.1
Prepaid expenses and other current assets	49.5	59.3
Total current assets	4,305.4	4,183.1
Property, plant and equipment, net	1,394.7	1,414.5
Cost in excess of net assets acquired	654.9	653.8
Intercompany notes receivable	200.0	200.0
Investment in subsidiaries	0.0	0.0
Other assets	303.8	306.6
Total assets	6,858.8	6,758.0
LIABILITIES AND EQUITY
Accounts payable	220.4	250.2
Accrued liabilities	211.8	203.7
Intercompany notes payable	0.0	0.0
Deferred income taxes	0.0	0.0
Short-term debt and current portion of long-term debt	17.5	17.2
Total current liabilities	449.7	471.1
Long-term debt	1.6	8.2
Intercompany notes payable	0.0	0.0
Accrued postretirement benefits	250.0	262.8
Pension liabilities	54.4	57.8
Deferred income taxes	0.0	0.0
Other long-term liabilities	61.9	56.0
Total liabilities	817.6	855.9
Redeemable noncontrolling interest	12.1	12.1
Total stockholders’ equity	6,029.1	5,890.0
Total Liabilities and Equity	6,858.8	6,758.0
Consolidation Eliminations
ASSETS
Cash and cash equivalents	0.0	0.0
Accounts receivable, net	0.0	0.0
Intercompany notes receivable	(2,515.5)	(2,390.8)
Inventories, net	0.0	0.0
Prepaid expenses and other current assets	0.0	0.0
Total current assets	(2,515.5)	(2,390.8)
Property, plant and equipment, net	0.0	0.0
Cost in excess of net assets acquired	0.0	0.0
Intercompany notes receivable	(200.0)	(200.0)
Investment in subsidiaries	(6,266.2)	(6,187.1)
Other assets	0.0	0.0
Total assets	(8,981.7)	(8,777.9)
LIABILITIES AND EQUITY
Accounts payable	0.0	0.0
Accrued liabilities	0.0	0.0
Intercompany notes payable	(2,515.5)	(2,390.8)
Deferred income taxes	0.0	0.0
Short-term debt and current portion of long-term debt	0.0	0.0
Total current liabilities	(2,515.5)	(2,390.8)
Long-term debt	0.0	0.0
Intercompany notes payable	(200.0)	(200.0)
Accrued postretirement benefits	0.0	0.0
Pension liabilities	0.0	0.0
Deferred income taxes	0.0	0.0
Other long-term liabilities	0.0	0.0
Total liabilities	(2,715.5)	(2,590.8)
Redeemable noncontrolling interest	0.0	0.0
Total stockholders’ equity	(6,266.2)	(6,187.1)
Total Liabilities and Equity	$ (8,981.7)	$ (8,777.9)