Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 22.0	$ 19.0	$ 39.7	$ 49.6
Other comprehensive income (loss):
Reclassifications of prior service benefit and actuarial loss amortization to earnings, net of tax	0.0	0.1	0.1	0.2
Currency translation adjustment	0.4	(1.0)	0.5	0.3
Comprehensive income	22.4	18.1	40.3	50.1
Less: Comprehensive income attributable to noncontrolling interests	1.6	1.0	3.0	2.1
Comprehensive income attributable to SunCoke Energy, Inc.	$ 20.8	$ 17.1	$ 37.3	$ 48.0