Consolidated Statements of Equity - USD ($) $ in Millions	Total	Total  SunCoke Energy, Inc.  Equity	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Non-controlling Interests
Beginning balance (in shares) at Dec. 31, 2022			98,815,780
Beginning balance at Dec. 31, 2022	$ 622.7	$ 585.6	$ 1.0	$ (184.0)	$ 728.1	$ (13.0)	$ 53.5	$ 37.1
Treasury stock, beginning balance (in shares) at Dec. 31, 2022				15,404,482
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	48.2	43.7					43.7	4.5
Reclassifications of prior service benefit and actuarial loss amortization to earnings, net of tax	0.1	0.1				0.1
Currency translation adjustment	0.2	0.2				0.2
Share-based compensation	4.3	4.3			4.3
Share issuances, net of shares withheld for taxes (in shares)			344,919
Share issuances, net of shares withheld for taxes	(3.4)	(3.4)			(3.4)
Dividends	(22.2)	(22.2)					(22.2)
Cash distribution to noncontrolling interests	(8.1)							(8.1)
Ending balance (in shares) at Sep. 30, 2023			99,160,699
Ending balance at Sep. 30, 2023	641.8	608.3	$ 1.0	$ (184.0)	729.0	(12.7)	75.0	33.5
Treasury stock, ending balance (in shares) at Sep. 30, 2023				15,404,482
Beginning balance (in shares) at Jun. 30, 2023			99,160,699
Beginning balance at Jun. 30, 2023	642.4	609.0	$ 1.0	$ (184.0)	727.9	(12.4)	76.5	33.4
Treasury stock, beginning balance (in shares) at Jun. 30, 2023				15,404,482
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	8.5	7.0					7.0	1.5
Currency translation adjustment	(0.3)	(0.3)				(0.3)
Share-based compensation	1.1	1.1			1.1
Dividends	(8.5)	(8.5)					(8.5)
Cash distribution to noncontrolling interests	(1.4)							(1.4)
Ending balance (in shares) at Sep. 30, 2023			99,160,699
Ending balance at Sep. 30, 2023	641.8	608.3	$ 1.0	$ (184.0)	729.0	(12.7)	75.0	33.5
Treasury stock, ending balance (in shares) at Sep. 30, 2023				15,404,482
Beginning balance (in shares) at Dec. 31, 2023			99,161,446
Beginning balance at Dec. 31, 2023	$ 645.5	614.2	$ 1.0	$ (184.0)	729.8	(12.8)	80.2	31.3
Treasury stock, beginning balance (in shares) at Dec. 31, 2023	15,404,482			15,404,482
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 77.7	72.2					72.2	5.5
Reclassifications of prior service benefit and actuarial loss amortization to earnings, net of tax	0.2	0.2				0.2
Currency translation adjustment	(0.9)	(0.9)				(0.9)
Share-based compensation	4.1	4.1			4.1
Share issuances, net of shares withheld for taxes (in shares)			335,363
Share issuances, net of shares withheld for taxes	(3.6)	(3.6)			(3.6)
Dividends	(27.6)	(27.6)					(27.6)
Cash distribution to noncontrolling interests	(4.4)							(4.4)
Ending balance (in shares) at Sep. 30, 2024			99,496,809
Ending balance at Sep. 30, 2024	$ 691.0	658.6	$ 1.0	$ (184.0)	730.3	(13.5)	124.8	32.4
Treasury stock, ending balance (in shares) at Sep. 30, 2024	15,404,482			15,404,482
Beginning balance (in shares) at Jun. 30, 2024			99,496,809
Beginning balance at Jun. 30, 2024	$ 666.7	636.9	$ 1.0	$ (184.0)	729.2	(13.6)	104.3	29.8
Treasury stock, beginning balance (in shares) at Jun. 30, 2024				15,404,482
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	33.3	30.7					30.7	2.6
Reclassifications of prior service benefit and actuarial loss amortization to earnings, net of tax	0.1	0.1				0.1
Currency translation adjustment	0.0
Share-based compensation	1.1	1.1			1.1
Dividends	(10.2)	(10.2)					(10.2)
Ending balance (in shares) at Sep. 30, 2024			99,496,809
Ending balance at Sep. 30, 2024	$ 691.0	$ 658.6	$ 1.0	$ (184.0)	$ 730.3	$ (13.5)	$ 124.8	$ 32.4
Treasury stock, ending balance (in shares) at Sep. 30, 2024	15,404,482			15,404,482