Business Segment Information - Adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2013
Adjusted EBITDA
Adjusted EBITDA attributable to SunCoke Energy, Inc.	$ 30.1	$ 46.0		$ 75.2	$ 116.8
Add: Adjusted EBITDA attributable to noncontrolling interests	20.1	18.2		56.3	42.0
Adjusted EBITDA	50.2	64.2		131.5	158.8
Adjustments to EBITDA [Abstract]
Adjustment to unconsolidated affiliate earnings	19.8	0.3		20.8	2.4
Restructuring charges	0.8	0.3		0.4	0.8
Depreciation, depletion and amortization expense	25.6	22.8		75.8	80.4
Interest expense, net	14.6	11.9		50.9	51.1
Income tax expense (benefit)	4.8	6.1		5.1	(48.9)
Sales discounts provided to customers due to sharing of nonconventional fuel tax credits	0.0	0.0		0.0	(0.5)
Asset and goodwill impairment	0.0	16.4		0.0	119.5
Coal Logistics deferred revenue	1.1	0.0		1.1	0.0
Net (loss) income	(16.5)	6.4		(22.6)	(46.0)
Asset impairment	0.0	16.4		0.0	119.5
Depreciation, depletion and amortization expense	25.6	22.8		75.8	80.4
Deferred income tax expense (benefit)	8.0	11.9		6.9	(58.0)
Loss on extinguishment of debt	0.0	0.0		9.4	15.4
Changes in working capital and other	(10.7)	(24.4)		13.5	(52.9)
Net cash provided by operating activities	6.4	$ 33.1		83.0	$ 58.4
Schedule of Equity Method Investments [Line Items]
Accrued sales discounts						$ 13.6
Settlement of accrued sales discounts			$ 13.1
Gain on settlement of accrued sales discounts			$ 0.5
VISA SunCoke Limited
Schedule of Equity Method Investments [Line Items]
Impairment of equity method investment	$ 19.4			$ 19.4