Supplemental Condensed Consolidating Financial Information - Consolidating Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenues
Sales and other operating revenue	$ 310.5	$ 323.9
Equity in earnings (loss) of subsidiaries	0.0	0.0
Other income	0.6	0.1
Total revenues	311.1	324.0
Costs and operating expenses
Cost of products sold and operating expenses	239.0	262.1
Selling, general and administrative expenses	23.7	12.6
Depreciation and amortization expense:	28.2	23.8
Asset impairment	10.7	0.0
Total costs and operating expenses	301.6	298.5
Operating (loss) income	9.5	25.5
Interest (income) expense, net - affiliate	0.0	0.0
Interest expense, net	14.0	13.9
Total interest expense (income), net	14.0	13.9
(Gain) loss on extinguishment of debt	(20.4)	9.4
(Loss) Income before income tax expense	15.9	2.2
Income tax expense	3.3	1.1
Loss from equity method investment	0.0	0.7
Net income	12.6	0.4
Less: Net income attributable to noncontrolling interests	16.7	4.4
Net (loss) income attributable to SunCoke Energy, Inc.	(4.1)	(4.0)
Comprehensive (loss) income	13.0	(3.1)
Less: Comprehensive income attributable to noncontrolling interests	16.7	4.4
Comprehensive (loss) income attributable to SunCoke Energy, Inc.	(3.7)	(7.5)
Issuer
Revenues
Sales and other operating revenue	0.0	0.0
Equity in earnings (loss) of subsidiaries	0.7	0.0
Other income	0.0	0.0
Total revenues	0.7	0.0
Costs and operating expenses
Cost of products sold and operating expenses	0.0	0.0
Selling, general and administrative expenses	3.0	2.0
Depreciation and amortization expense:	0.0	0.0
Asset impairment	0.0
Total costs and operating expenses	3.0	2.0
Operating (loss) income	(2.3)	(2.0)
Interest (income) expense, net - affiliate	0.0	0.0
Interest expense, net	1.5	2.8
Total interest expense (income), net	1.5	2.8
(Gain) loss on extinguishment of debt	0.0	0.0
(Loss) Income before income tax expense	(3.8)	(4.8)
Income tax expense	0.3	(0.8)
Loss from equity method investment		0.0
Net income	(4.1)	(4.0)
Less: Net income attributable to noncontrolling interests	0.0	0.0
Net (loss) income attributable to SunCoke Energy, Inc.	(4.1)	(4.0)
Comprehensive (loss) income	(3.7)	(7.5)
Less: Comprehensive income attributable to noncontrolling interests	0.0	0.0
Comprehensive (loss) income attributable to SunCoke Energy, Inc.	(3.7)	(7.5)
Guarantor Subsidiaries
Revenues
Sales and other operating revenue	42.6	41.0
Equity in earnings (loss) of subsidiaries	11.3	3.4
Other income	0.1	0.1
Total revenues	54.0	44.5
Costs and operating expenses
Cost of products sold and operating expenses	33.9	30.4
Selling, general and administrative expenses	8.9	7.6
Depreciation and amortization expense:	2.2	2.1
Asset impairment	0.0
Total costs and operating expenses	45.0	40.1
Operating (loss) income	9.0	4.4
Interest (income) expense, net - affiliate	(2.0)	(1.8)
Interest expense, net	0.0	(0.3)
Total interest expense (income), net	(2.0)	(2.1)
(Gain) loss on extinguishment of debt	0.0	0.0
(Loss) Income before income tax expense	11.0	6.5
Income tax expense	6.1	2.8
Loss from equity method investment		0.0
Net income	4.9	3.7
Less: Net income attributable to noncontrolling interests	0.0	0.0
Net (loss) income attributable to SunCoke Energy, Inc.	4.9	3.7
Comprehensive (loss) income	4.9	3.6
Less: Comprehensive income attributable to noncontrolling interests	0.0	0.0
Comprehensive (loss) income attributable to SunCoke Energy, Inc.	4.9	3.6
Non- Guarantor Subsidiaries
Revenues
Sales and other operating revenue	268.9	282.9
Equity in earnings (loss) of subsidiaries	0.0	0.0
Other income	0.5	0.0
Total revenues	269.4	282.9
Costs and operating expenses
Cost of products sold and operating expenses	206.1	231.7
Selling, general and administrative expenses	11.8	3.0
Depreciation and amortization expense:	26.0	21.7
Asset impairment	10.7
Total costs and operating expenses	254.6	256.4
Operating (loss) income	14.8	26.5
Interest (income) expense, net - affiliate	2.0	1.8
Interest expense, net	12.5	11.4
Total interest expense (income), net	14.5	13.2
(Gain) loss on extinguishment of debt	(20.4)	9.4
(Loss) Income before income tax expense	20.7	3.9
Income tax expense	(3.1)	(0.9)
Loss from equity method investment		0.7
Net income	23.8	4.1
Less: Net income attributable to noncontrolling interests	16.7	4.4
Net (loss) income attributable to SunCoke Energy, Inc.	7.1	(0.3)
Comprehensive (loss) income	24.2	0.7
Less: Comprehensive income attributable to noncontrolling interests	16.7	4.4
Comprehensive (loss) income attributable to SunCoke Energy, Inc.	7.5	(3.7)
Combining and Consolidating Adjustments
Revenues
Sales and other operating revenue	(1.0)	0.0
Equity in earnings (loss) of subsidiaries	(12.0)	(3.4)
Other income	0.0	0.0
Total revenues	(13.0)	(3.4)
Costs and operating expenses
Cost of products sold and operating expenses	(1.0)	0.0
Selling, general and administrative expenses	0.0	0.0
Depreciation and amortization expense:	0.0	0.0
Asset impairment	0.0
Total costs and operating expenses	(1.0)	0.0
Operating (loss) income	(12.0)	(3.4)
Interest (income) expense, net - affiliate	0.0	0.0
Interest expense, net	0.0	0.0
Total interest expense (income), net	0.0	0.0
(Gain) loss on extinguishment of debt	0.0	0.0
(Loss) Income before income tax expense	(12.0)	(3.4)
Income tax expense	0.0	0.0
Loss from equity method investment		0.0
Net income	(12.0)	(3.4)
Less: Net income attributable to noncontrolling interests	0.0	0.0
Net (loss) income attributable to SunCoke Energy, Inc.	(12.0)	(3.4)
Comprehensive (loss) income	(12.4)	0.1
Less: Comprehensive income attributable to noncontrolling interests	0.0	0.0
Comprehensive (loss) income attributable to SunCoke Energy, Inc.	$ (12.4)	$ 0.1