CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 191.8	$ 227.0
Accounts receivable, net	516.4	473.9
Inventory, net	664.0	609.2
Deferred tax assets, current	77.4	73.2
Other current assets	43.0	59.4
Total current assets	1,492.6	1,442.7
Property, plant and equipment	5,952.4	5,943.9
Accumulated depreciation	(3,980.1)	(3,931.6)
Property, plant and equipment, net	1,972.3	2,012.3
Other non-current assets:
Investment in AFSG Holdings, Inc.	55.6	55.6
Investment in Magnetation LLC	145.0	150.0
Goodwill	37.1	37.1
Deferred tax assets, non-current	88.4	88.2
Other non-current assets	115.1	117.2
TOTAL ASSETS	3,906.1	3,903.1
Current liabilities:
Accounts payable	592.4	538.3
Accrued liabilities	185.7	164.8
Current portion of long-term debt	0.7	0.7
Current portion of pension and other postretirement benefit obligations	109.8	108.6
Total current liabilities	888.6	812.4
Non-current liabilities:
Long-term debt	1,411.9	1,411.2
Pension and other postretirement benefit obligations	1,607.7	1,661.7
Other non-current liabilities	107.6	108.8
TOTAL LIABILITIES	4,015.8	3,994.1
Equity (deficit):
Common stock, authorized 200,000,000 shares of $.01 par value each; issued 149,597,084 and 149,094,571 shares in 2013 and 2012; outstanding 136,310,324 and 135,944,172 shares in 2013 and 2012	1.5	1.5
Additional paid-in capital	2,073.6	2,069.7
Treasury stock, common shares at cost, 13,286,760 and 13,150,399 shares in 2013 and 2012	(173.9)	(173.3)
Accumulated deficit	(2,414.2)	(2,404.3)
Accumulated other comprehensive income (loss)	(18.6)	1.1
Total stockholders' equity (deficit)	(531.6)	(505.3)
Noncontrolling interests	421.9	414.3
TOTAL EQUITY (DEFICIT)	(109.7)	(91.0)
TOTAL LIABILITIES AND EQUITY (DEFICIT)	3,906.1	3,903.1
Variable Interest Entity, Primary Beneficiary [Member] | SunCoke Middletown [Member]
Current assets:
Cash and cash equivalents	13.6	0
Accounts receivable, net	1.7	1.0
Inventory, net	22.0	28.3
Property, plant and equipment	415.1	414.5
Accumulated depreciation	(18.5)	(15.0)
Other assets (liabilities), net	0.2	(1.2)
Current liabilities:
Accounts payable	14.1	15.4
Equity (deficit):
Noncontrolling interests	420.0	412.2
Variable Interest Entity, Primary Beneficiary [Member] | Other Variable Interest Entities [Member]
Current assets:
Property, plant and equipment	11.5	11.4
Accumulated depreciation	(9.0)	(8.9)
Other assets (liabilities), net	1.5	1.8
Equity (deficit):
Noncontrolling interests	$ 1.9	$ 2.1