Supplemental Condensed Consolidating Financial Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenues
Sales and other operating revenue	$ 451.5	$ 480.6
Equity in Earnings of Subsidiaries	0	0
Other income, net	2.4	0.7
Total revenues	453.9	481.3
Costs and operating expenses
Cost of products sold and operating expenses	382.4	408.3
Selling, general and administrative expenses	20.6	20.7
Depreciation, depletion and amortization	23.9	18.4
Total costs and operating expenses	426.9	447.4
Operating income	27.0	33.9
Interest income-affiliate	0	0
Interest cost-affiliate	0	0
Interest expense, net	15.8	12.0
Total financing expense, net	15.8	12.0
Income before income tax expense	11.2	21.9
Income tax expense	4.8	5.3
Net income	6.4	16.6
Less: Net income (loss) attributable to noncontrolling interests	4.3	(0.3)
Net income attributable to SunCoke Energy, Inc. / net parent investment	2.1	16.9
Comprehensive income	6.0	16.4
Less: Comprehensive income (loss) attributable to noncontrolling interests	4.3	(0.3)
Comprehensive income attributable to SunCoke Energy, Inc.	1.7	16.7
Issuer [Member]
Revenues
Sales and other operating revenue	0	0
Equity in Earnings of Subsidiaries	13.1	28.8
Other income, net	0	0
Total revenues	13.1	28.8
Costs and operating expenses
Cost of products sold and operating expenses	0	0
Selling, general and administrative expenses	2.5	2.9
Depreciation, depletion and amortization	0	0
Total costs and operating expenses	2.5	2.9
Operating income	10.6	25.9
Interest income-affiliate	0	0
Interest cost-affiliate	0	0
Interest expense, net	9.8	12.1
Total financing expense, net	9.8	12.1
Income before income tax expense	0.8	13.8
Income tax expense	(1.3)	(3.1)
Net income	2.1	16.9
Less: Net income (loss) attributable to noncontrolling interests	0	0
Net income attributable to SunCoke Energy, Inc. / net parent investment	2.1	16.9
Comprehensive income	1.7	16.7
Less: Comprehensive income (loss) attributable to noncontrolling interests	0	0
Comprehensive income attributable to SunCoke Energy, Inc.	1.7	16.7
Guarantor Subsidiaries [Member]
Revenues
Sales and other operating revenue	136.9	161.4
Equity in Earnings of Subsidiaries	19.6	14.1
Other income, net	2.4	0.7
Total revenues	158.9	176.2
Costs and operating expenses
Cost of products sold and operating expenses	115.6	121.5
Selling, general and administrative expenses	12.5	11.0
Depreciation, depletion and amortization	10.1	8.9
Total costs and operating expenses	138.2	141.4
Operating income	20.7	34.8
Interest income-affiliate	(1.8)	(1.8)
Interest cost-affiliate	0	0
Interest expense, net	(1.9)	(1.8)
Total financing expense, net	(3.7)	(3.6)
Income before income tax expense	24.4	38.4
Income tax expense	5.0	3.2
Net income	19.4	35.2
Less: Net income (loss) attributable to noncontrolling interests	0	0
Net income attributable to SunCoke Energy, Inc. / net parent investment	19.4	35.2
Comprehensive income	18.9	34.8
Less: Comprehensive income (loss) attributable to noncontrolling interests	0	0
Comprehensive income attributable to SunCoke Energy, Inc.	18.9	34.8
Non-Guarantor Subsidiaries [Member]
Revenues
Sales and other operating revenue	314.6	319.2
Equity in Earnings of Subsidiaries	0	0
Other income, net	0	0
Total revenues	314.6	319.2
Costs and operating expenses
Cost of products sold and operating expenses	266.8	286.8
Selling, general and administrative expenses	5.6	6.8
Depreciation, depletion and amortization	13.8	9.5
Total costs and operating expenses	286.2	303.1
Operating income	28.4	16.1
Interest income-affiliate	0	0
Interest cost-affiliate	1.8	1.8
Interest expense, net	7.9	1.7
Total financing expense, net	9.7	3.5
Income before income tax expense	18.7	12.6
Income tax expense	1.1	5.2
Net income	17.6	7.4
Less: Net income (loss) attributable to noncontrolling interests	4.3	(0.3)
Net income attributable to SunCoke Energy, Inc. / net parent investment	13.3	7.7
Comprehensive income	17.7	7.6
Less: Comprehensive income (loss) attributable to noncontrolling interests	4.3	(0.3)
Comprehensive income attributable to SunCoke Energy, Inc.	13.4	7.9
Combining and Consolidating Adjustments [Member]
Revenues
Sales and other operating revenue
Equity in Earnings of Subsidiaries	(32.7)	(42.9)
Other income, net
Total revenues	(32.7)	(42.9)
Costs and operating expenses
Cost of products sold and operating expenses
Selling, general and administrative expenses
Depreciation, depletion and amortization
Total costs and operating expenses
Operating income	(32.7)	(42.9)
Interest income-affiliate	1.8	1.8
Interest cost-affiliate	(1.8)	(1.8)
Interest expense, net
Total financing expense, net
Income before income tax expense	(32.7)	(42.9)
Income tax expense
Net income	(32.7)	(42.9)
Less: Net income (loss) attributable to noncontrolling interests
Net income attributable to SunCoke Energy, Inc. / net parent investment	(32.7)	(42.9)
Comprehensive income	(32.3)	(42.7)
Less: Comprehensive income (loss) attributable to noncontrolling interests
Comprehensive income attributable to SunCoke Energy, Inc.	$ (32.3)	$ (42.7)