Debt and Financing Obligation - Narrative (Details) - USD ($)	Jan. 11, 2018	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Outstanding balance		$ 885,800,000	$ 887,300,000
7.625 percent senior notes, due 2019 (2019 Notes) | Senior notes
Debt Instrument [Line Items]
Repayments of debt	$ 46,100,000
Accrued and unpaid interest	1,500,000
Amortization of debt issuance costs	300,000
Outstanding balance		0	44,600,000
Term loan, due 2022 (Term Loan) | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	45,000,000
Additional debt issuance costs	$ 300,000
Outstanding balance		44,400,000	0
Revolving Credit Facility | Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		100,000,000
Letters of credit outstanding under revolving facility		24,000,000
Outstanding balance		0
Remaining borrowing capacity		76,000,000
Partnership's revolving credit facility, due 2022 as of December, 2017 (Partnership Revolver) | Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Outstanding balance		130,000,000	$ 130,000,000
Partnership's revolving credit facility, due 2022 as of December, 2017 (Partnership Revolver) | Line of Credit | SunCoke Energy Partners, L.P. | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		285,000,000
Letters of credit outstanding under revolving facility		1,900,000
Outstanding balance		130,000,000
Remaining borrowing capacity		$ 153,100,000