Share-Based Compensation (Equity Classified Awards Narrative) (Details)	1 Months Ended		12 Months Ended
	Dec. 31, 2017 shares	Feb. 28, 2017 shares	Dec. 31, 2018 USD ($) Installment $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Feb. 14, 2018 shares	Jul. 13, 2011 shares
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value of stock options exercised | $			$ 800,000	$ 300,000	$ 0
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of annual installment in which stock option exercisable | Installment			3
Period from grant date for annual installment (in years)			1 year
Shares granted (shares)			32,128	22,628	0
Total fair value of non-option award units vested | $			$ 1,200,000	$ 2,300,000	$ 3,700,000
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (shares)	148,148	237,610	96,389	385,758
Performance Share Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage adjustment of award determined by pre-tax return on capital (as a percent)			0.00%
Performance Share Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage adjustment of award determined by pre-tax return on capital (as a percent)			200.00%
SunCoke LTPEP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issuable (in shares)						6,000,000	1,600,000
Common stock issuable pursuant to new awards (in shares)						1,500,000	7,500,000
SunCoke LTPEP | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of annual installment in which stock option exercisable | Installment			3
Period from grant date for annual installment (in years)			1 year
Expiration period			10 years
SunCoke LTPEP | Performance Based Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing common stock price (USD per share) | $ / shares				$ 14.78	$ 9.50
Number of trading days					15 days
Measurement period					3 years
SunCoke LTPEP | Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Measurement period			3 years
SunCoke LTPEP | Performance Share Units | Pre-tax return of capital for Coke and Coal Logistics businesses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing common stock price (USD per share) | $ / shares			$ 9.00
Number of trading days			15 days
Measurement period			3 years
Percent of award allocation			50.00%
SunCoke LTPEP | Performance Share Units | Pre-tax return of capital for coke business
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Measurement period			3 years
SunCoke LTPEP | Performance Share Units | Minimum | Pre-tax return of capital for coke business
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout percentage			50.00%
Percentage adjustment of award determined by pre-tax return on capital (as a percent)			0.00%
SunCoke LTPEP | Performance Share Units | Maximum | Pre-tax return of capital for coke business
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout percentage			150.00%
Percentage adjustment of award determined by pre-tax return on capital (as a percent)			250.00%