Debt and Financing Obligation - Revolving Facility Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Outstanding balance	$ 507.1	$ 543.8
Revolving Credit Facility | Line of Credit | SunCoke Revolving Credit Facility, Due 2024
Debt Instrument [Line Items]
Outstanding balance	0.0
Remaining borrowing capacity	350.0
Letter of Credit | Line of Credit | SunCoke Revolving Credit Facility, Due 2024
Debt Instrument [Line Items]
Outstanding balance	$ 22.4