Share-Based Compensation (Details Textual) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($) annual_installment $ / shares shares	Jun. 30, 2016 USD ($)
Director
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Compensation expense	$ 0.3	$ 0.2
Stock options
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Historical volatility rate	90.00%
Implied volatility rate	10.00%
Implied volatility valuation period	90 days
Stock options | Suncoke LTPEP
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Number of annual installment in which stock option exercisable (in installments) | annual_installment	3
Period from grant date for annual installment (in years)	1 year
Stock options, time until expiration (in years)	10 years
Performance based options | Suncoke LTPEP
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Maximum closing stock price threshold for performance based options (in dollars per share) | $ / shares	$ 14.78
Threshold percentage	150.00%
Closing stock price threshold for performance based options (in dollars per share) | $ / shares	$ 9.85
Closing stock price threshold for performance based options, number of trading days	15 days
Measurement period	3 years
Restricted stock units
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Number of annual installment in which stock option exercisable (in installments) | annual_installment	3
Period from grant date for annual installment (in years)	1 year
Restricted stock (in shares) | shares	22,628
Fair value grant (in dollars per share) | $ / shares	$ 9.85
PSUs | Suncoke LTPEP
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Measurement period	3 years
PSUs | Minimum
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Percent of original award granted	0.00%
PSUs | Maximum
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Percent of original award granted	250.00%
Restricted Stock Units Settled in Cash
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Number of annual installment in which stock option exercisable (in installments) | annual_installment	3
Period from grant date for annual installment (in years)	1 year
Restricted stock (in shares) | shares	95,364
Fair value grant (in dollars per share) | $ / shares	$ 9.85
Closing price per share (in dollars per share) | $ / shares	$ 10.90
Share-based arrangements, liability	$ 0.6
Share-based arrangements, liability, current	0.4
Share-based arrangements, liability, noncurrent	0.2
Cash incentive award
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Share-based arrangements, liability, noncurrent	$ 0.4
Cash incentive award | Suncoke LTCIP
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Measurement period	3 years
Grant date fair value of award	$ 0.7
Percent of award allocation	50.00%
Cash incentive award | Maximum | Suncoke LTCIP
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Percent of original award granted	250.00%