Business Segment Information - Adjusted EBITDA (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net (loss) income attributable to SunCoke Energy, Inc.	$ (2,700,000)	$ (163,000,000.0)	$ 8,700,000	$ (150,900,000)
Add: Net income (loss) attributable to noncontrolling interests	1,300,000	(100,000)	3,600,000	3,300,000
Net (loss) income	(1,400,000)	(163,100,000)	12,300,000	(147,600,000)
Add:
Long-lived asset and goodwill impairment	0	247,400,000	0	247,400,000
Depreciation and amortization expense	33,500,000	35,600,000	101,700,000	109,800,000
Interest expense, net	13,700,000	15,700,000	43,200,000	45,600,000
Gain on extinguishment of debt	(500,000)	(1,500,000)	(3,400,000)	(1,500,000)
Income tax expense (benefit)	200,000	(63,500,000)	12,800,000	(57,300,000)
Contingent consideration adjustments	0	(3,900,000)	0	(4,200,000)
Restructuring costs	2,300,000	0	2,300,000	0
Simplification Transaction costs	0	0	0	4,900,000
Adjusted EBITDA	47,800,000	66,700,000	168,900,000	197,100,000
Subtract: Adjusted EBITDA attributable to noncontrolling interests	2,300,000	1,600,000	6,600,000	39,100,000
Adjusted EBITDA attributable to SunCoke Energy, Inc.	$ 45,500,000	65,100,000	$ 162,300,000	158,000,000.0
SunCoke Energy Partners, L.P. | Fair Value, Inputs, Level 3 | Convent Marine Terminal
Add:
Contingent consideration liability		$ 0		$ 0