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Cover Page - USD ($)
 12 Months Ended
Dec. 31, 2020
Feb. 19, 2021
Jun. 30, 2020
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2020    
Document Transition Report false    
Entity File Number 001-35243    
Entity Registrant Name SUNCOKE ENERGY, INC.    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 90-0640593    
Entity Address, Address Line One 1011 Warrenville Road    
Entity Address, Address Line Two Suite 600    
Entity Address, City or Town Lisle    
Entity Address, State or Province IL    
Entity Address, Postal Zip Code 60532    
City Area Code 630    
Local Phone Number 824-1000    
Title of 12(b) Security Common Stock, $0.01 par value    
Trading Symbol SXC    
Security Exchange Name NYSE    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Entity Shell Company false    
Entity Public Float     $ 243,652,539
Entity Common Stock, Shares Outstanding (in shares)   82,806,106  
Documents Incorporated by Reference Portions of the SunCoke Energy, Inc. 2021 definitive Proxy Statement, which will be filed with the Securities and Exchange Commission within 120 days after December 31, 2020, are incorporated by reference in Part III of this Form 10-K.    
Entity Central Index Key 0001514705    
Current Fiscal Year End Date --12-31    
Document Fiscal Year Focus 2020    
Document Fiscal Period Focus FY    
Amendment Flag false