Share-Based Compensation - Narrative (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2024 USD ($) installment $ / shares shares	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Director
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Compensation expense	$ 0.1	$ 0.3
RSUs
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Share based payment award, grants in period (in shares) | shares	268,565
Fair value grant (in dollars per share) | $ / shares	$ 10.86
Number of annual installment in which stock option exercisable (in installments) | installment	3
Period from grant date for annual installment (in years)	1 year
PSUs | Minimum
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Percent of original award granted	25.00%
PSUs | Maximum
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Percent of original award granted	200.00%
Restricted Stock Units Settled in Cash
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Share based payment award, grants in period (in shares) | shares	165,384
Fair value grant (in dollars per share) | $ / shares	$ 10.96
Number of annual installment in which stock option exercisable (in installments) | installment	3
Period from grant date for annual installment (in years)	1 year
Award liability	$ 1.7		$ 2.8
Cash incentive award | Suncoke LTCIP
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Award liability	7.2		$ 8.1
Grant date fair value of award	$ 2.6
Percent of award allocation	50.00%
Measurement period	3 years